Life cycle of a dam: Training – Human capability is the asset behind every dam

Throughout our ‘Life cycle of a dam’ series, we have explored the physical journey of a dam, through inception, design and construction, first filling, operation, upgrades and decommissioning. Every stage depends on people who understand the asset, recognise emerging risks, make informed decisions and pass knowledge on to its future custodians.

Here, two of our nationally accredited trainers with the Entura clean energy and water institute, senior civil engineers Sally Fracalossi and David Wightman, share their insights about knowledge sharing, capability building and training in the dams industry.

Integral to the safety, resilience and ability of a dam to fulfil its purpose throughout its long life cycle is the capability of the people and organisations responsible for it. While the physical dam structure may endure for generations, the workforce and operating context will continually evolve as infrastructure ages, the climate shifts, standards change and communities downstream grow.

Dam owners need to preserve knowledge, strengthen judgement and ensure that the next generation inherits both the asset and the ability to manage it well.

Treat capability as a dam safety control

Most dam owners have structured approaches to monitoring, inspections, safety reviews and emergency planning. Capability can be harder to quantify and assess.

Dam safety depends on people recognising changes in asset behaviour, interpreting evidence, escalating concerns and making sound decisions under pressure. Operators and surveillance personnel are often the first to notice that something has changed. If they lack the knowledge, confidence or authority to respond, even well-designed systems may not provide the protection intended.

Capability should therefore be managed with the same discipline as other dam safety controls. It requires consideration of the dam, its credible failure modes and consequences, the decisions required to manage the associated risks, and the people entrusted with those decisions.

Match capability to risk and responsibility

Capability requirements should be tailored to each role within a dam owner’s organisation. Executives need to understand dam safety risk and governance obligations. Engineers require appropriate technical competence. Operators and inspectors need the practical ability to recognise, document and escalate abnormal conditions. These requirements should reflect the complexity and consequences of the assets being managed.

Clear accountabilities are essential. If an organisation has not defined who is responsible for critical activities and decisions, it will struggle to determine what capability is required or understand the dam safety risks arising from identified gaps.

Preserve knowledge before it is lost

Much of the knowledge about a dam is learned over many years: how it behaves, seasonal changes or trends, why previous decisions were made, and which observations warrant closer attention. Some of this knowledge is documented, but much remains with individuals and can be lost when experienced personnel leave.

Knowledge transfer must be deliberate. Mentoring, succession planning, shared inspections, technical reviews and handovers help turn personal experience into organisational knowledge. Documentation matters, but it rarely captures the judgement behind a decision. That judgement must also be discussed and passed on.

Build future capability before it becomes urgent

Training needs should not be based only on current roles and gaps. Owners should consider what expertise and leadership they will need as assets age, operating conditions change, technology develops and experienced practitioners retire.

This long-term view creates time to develop people through mentoring, practical exposure and increasing responsibility. It also helps owners decide which capabilities they need to develop internally and which specialist expertise to source externally when required.

Test competence, then keep it current

For critical dam safety roles, dam owners need evidence that people can apply knowledge in practice, manage related responsibilities and respond appropriately when conditions depart from expected behaviour. Accredited assessment can provide defensible evidence of competence.

A valid accreditation or qualification does not necessarily mean that a person retains the same level of knowledge as time passes. Competence can weaken when tasks are performed infrequently, procedures change or knowledge is not refreshed. Refresher cycles should reflect asset consequence and complexity, task exposure, individual experience, audit findings and changes in roles or procedures.

Reinforce learning through practice and feedback

No single development method is sufficient. Formal training provides foundations, while mentoring, site experience, emergency exercises, peer learning and participation in inspections develop judgement and asset-specific understanding.

Feedback is particularly important. Operators and inspectors are more likely to recognise the value of surveillance when they understand how their observations are used, what investigations followed and why escalation mattered. Without that feedback loop, surveillance can become a routine compliance task rather than an informed contribution to dam safety.

Senior leaders set the conditions for this learning to endure. They determine whether capability gaps are treated as governance risks, whether knowledge transfer and refreshers are resourced, and whether learning is connected to everyday decisions.

Throughout this series, we have followed the physical lifecycle of a dam from inception to decommissioning. At every stage, safe stewardship depends on people who understand the asset, recognise emerging risks, exercise sound judgement and pass knowledge on. A dam may endure for generations, but good stewardship only endures if capability is developed and sustained too.

PRINCIPLES IN PRACTICE: THE ENTURA CLEAN ENERGY AND WATER INSTITUTE (ECEWI)

Around the world, dam owners are grappling with how to retain critical knowledge, strengthen governance and prepare the next generation of practitioners. Increasingly, the focus is shifting from delivering isolated training events to building sustained organisational capability.

The Entura clean energy and water institute (ECEWI) supports this through programs shaped around the risks, roles and operating context of each organisation. The objective is to help organisations strengthen their own capability and capacity over the long term.

One example is ECEWI’s involvement in the South Asia Regional Infrastructure Connectivity (SARIC) initiative. Through this Australian Government-supported program, ECEWI has delivered dam safety training programs for engineers and senior executives from water and hydropower organisations across South Asia. Participants explored topics including dam safety risk management, surveillance, inspection, monitoring and emergency preparedness, supported by site visits and engagement with industry practitioners. Bringing together participants from multiple countries and organisations created opportunities to compare approaches, build professional networks and strengthen understanding across the region. The focus was not simply on individual learning, but on building knowledge that participants could take back into their organisations and apply within their own governance and operational frameworks.

In Malaysia, ECEWI has worked with MYCOLD, UNITEN and industry partners to contribute to the development of a Certified Dam Safety Inspector program. This covered surveillance, inspection, monitoring and reporting with practical site-based experience and formal assessment. The program created a structured pathway that local organisations could continue to refine and sustain. In this respect, the program illustrates the difference between training people and strengthening institutions. The capability remains even after the original training has finished because it is embedded in recognised competencies, assessment processes and local ownership.

ECEWI has also developed long-term capacity-building partnerships. ECEWI’s work with Sarawak Energy has evolved over many years into structured learning pathways across multiple technical disciplines. Dam safety surveillance officer training has supported the development of local capability through accredited learning and train-the-trainer approaches designed to sustain knowledge within the organisation.

Closer to home, ECEWI has worked with Australian water utilities and irrigation authorities to analyse gaps and then design and deliver bespoke training aligned with each organisation’s dam safety needs. ECEWI customises the training to the specific asset portfolio of each organisation, with their particular operational challenges, regulatory obligations and potential scenarios, making training relevant and immediately applicable in practice.

Although these examples differ in scale and context, they are all based in the recognition that dam safety depends on more than sound infrastructure. It depends on capable people, supported by capable institutions, making informed decisions throughout the life of the asset. Building knowledge through formal training can be an important part of the journey of building organisational capability, but it must be part of a broader system that also focuses on retaining knowledge and passing it on from one generation of dam professionals to the next.

This concludes our ‘Life cycle of a dam’ series. However, our dams specialists always have more to say. Keep an eye on our socials and our website to keep up to date with all our thought leadership articles.

ABOUT THE AUTHORS

Sally Fracalossi is one of Entura’s senior dams engineers. She joined Entura’s Dams and Geotechnical Team in 2020, following 5 years in a multinational private consultancy where she gained broad civil engineering and project management experience. Sally is experienced in numerous aspects of dam engineering, including dam design, dam safety assessments and inspections, risk assessment and construction support. She has also been involved in developing dam safety emergency management plans, operations and maintenance manuals, and is actively involved in facilitating dam safety training as a certified trainer through the Entura clean energy and water institute (ECEWI).

David Wightman joined Entura’s Dams and Geotechnical Team in 2019 as a Senior Dams Engineer. David has had a 25-year career in engineering and has worked for asset owners and as a consultant. At Entura, he is involved in dam safety inspections, reporting writing and reviews, and mentoring emerging engineers. He has a particular interest in review of dam safety programs, including prioritising of dam deficiencies and upgrades, and optimising surveillance and monitoring to suit relevant failure modes. David is actively involved in facilitating dam safety training as a certified trainer through the Entura clean energy and water institute (ECEWI).

Life cycle of a dam – Phase 6: Decommissioning – Ending well

By Joey Scicluna

This article completes our ‘Life cycle of a dam’ series, which has explored inception, development, first filling, operation and upgrades and now turns to decommissioning.

An asset may eventually reach a point where its future needs to be reconsidered. A dam may no longer serve its original purpose, safety risks may have increased, or the cost of maintaining the asset may outweigh its benefits. In some cases, the most responsible decision isn’t another upgrade, but bringing the asset’s operational life to a close.

When it becomes the right option, decommissioning isn’t a sign that a dam has failed. It’s simply another stage in the life cycle, requiring the same planning, risk-based decision-making and long-term considerations as every phase that came before.

The dam owner must return to some of the same questions considered at the start of the project: What outcomes are we trying to achieve? What risks are acceptable? How will the surrounding environment and community be affected? What legacy do we want to leave?

Conduct a risk assessment

The decision to decommission a dam is usually informed by a comprehensive risk assessment. These assessments identify potential hazards and failure modes, evaluate the likelihood and consequences of failure, assess whether risks are as low as reasonably practicable, and compare the effectiveness of potential risk reduction measures.

In many cases, the preferred outcome will be an upgrade rather than decommissioning. When upgrade options are being assessed, however, decommissioning is often evaluated alongside them. This allows owners to compare not only cost, but also the level of risk reduction achieved, future operational requirements and the long-term value of each option. The objective is to identify the option that delivers the greatest long-term benefit for owners, communities and the environment.

Assess the options and the broad context

The options assessment is rarely based on engineering considerations alone. Over decades of operation, a dam becomes part of a wider environmental, social and economic system. It influences waterways, ecosystems, recreation, cultural heritage and nearby communities. Removing a dam therefore requires an understanding of how these interconnected systems may respond.

Successful decommissioning balances engineering requirements with environmental, social and heritage considerations. Cost, future operational requirements, environmental impacts, community expectations and the degree of risk reduction achieved all contribute to the final decision. Achieving the best outcome often requires input from engineers, hydrologists, environmental scientists, heritage specialists, planners, regulators and stakeholders to ensure the project is technically sound while also delivering broader environmental and community benefits.

Design for a new condition

Before deciding how to remove the dam, the project team needs to define the future landscape and what the site should become. Some projects focus on restoring natural landforms and river processes; others create new community assets. Whatever the objective, it should be established early to inform the design process.

The engineering challenge is to create a sustainable, low-risk future condition. This may involve determining the appropriate breach width and geometry, modifying or removing outlet works, assessing downstream flood behaviour, managing inflows during construction, and controlling erosion and sediment movement. A dam may also provide incidental flood mitigation even when that was not its primary purpose, so it’s important to understand the downstream hydraulic consequences of removal.

Sediment requires particular attention. Reservoirs can contain deposits accumulated over decades, and exposing or remobilising them may affect water quality, river stability and downstream habitat. The design therefore needs to consider how sediment will behave, how the waterway will adjust and how vegetation, ecological restoration and future community use will be established within the former reservoir.

Manage the transition carefully

Even a well-developed design can’t anticipate every condition that could emerge during decommissioning. Lowering the reservoir may expose sediment deposits, previous drainage paths or site constraints that affect how the works should proceed.

Careful staging, monitoring and construction supervision allow the project team to test assumptions against actual site conditions and adjust the works where necessary. This adaptive approach is particularly important while flows are being redirected, landforms reshaped and rehabilitation established. It helps manage short-term construction risks without losing sight of the site’s intended long-term condition.

Leave a positive legacy

When decommissioning is the appropriate option and is done well, it should leave behind a site that remains safe and functional. It’s also an opportunity to consider how the site itself could continue to provide value in new ways. The dam may have reached the end of its operational life, but the site itself can continue to provide value in new ways.

PRINCIPLES IN PRACTICE: TOLOSA DAM

The decommissioning of Tolosa Dam demonstrates how the final chapter of a dam’s life can become the beginning of something entirely different. Entura supported this project with multidisciplinary services from start to finish.

Constructed in 1880 and later raised in 1915 and 1922, the dam had long since fallen into disuse as a water supply asset. Risk assessments found it no longer met contemporary safety requirements and needed to be removed. The central question was what role the site should play in the future.

Located beside residential neighbourhoods, a school and existing public open space, the reservoir occupied land with significant community potential. TasWater’s decision to decommission the dam and return the land to Glenorchy City Council created an opportunity to rethink the site and its purpose.

The work involved environmental and heritage assessments, erosion and sediment control planning, rehabilitation planning, hydraulic investigations and stakeholder engagement alongside engineering design. As plans for the future parkland evolved, the decommissioning design evolved alongside them, ensuring that the future use of the site shaped the way the works were undertaken.

An important part of the process was recognising that although the dam had reached the end of its operational life, its history still mattered to the community. Rather than removing every trace of the former reservoir, sections of the embankment were retained and incorporated into the final park design. Visitors can still understand the footprint of the original dam and its role in Glenorchy’s development. Five ornamental ponds were also incorporated into the landscape, maintaining a connection with the site’s water management history.

This project highlights the importance of carefully managing transition. Water, sediment and erosion required active management throughout construction. The site’s landforms were progressively reshaped to direct runoff towards temporary sediment-control ponds, allowing water quality to be managed while works proceeded. Construction supervision ensured that the works aligned with both regulatory requirements and the broader objectives for the site’s future use.

Today, the former reservoir has become a community destination. Safety risks have been removed, environmental impacts have been managed and a redundant asset has been transformed into a new public space. Perhaps the most important lesson from Tolosa is that the success of a decommissioning project is often defined less by what is removed than by what replaces it.

Similar themes can be seen in other decommissioning projects our teams have delivered. At Waratah Dam, extensive environmental and heritage investigations informed a strategy that balanced dam safety requirements with the restoration of natural river processes. At Pioneer Dam, environmental monitoring, adaptive construction management and rehabilitation planning helped restore the flow of Bradshaws Creek while supporting the continued recreational use of Pioneer Lake. Each project had a different context and different objectives, but all required careful consideration of what should follow the dam itself.

This concludes our 6-part ‘Life cycle of a dam’ series. However, our dams specialists have more to say. We’ll shortly be bringing you an article on a crucial, cross-cutting element for dam safety across the life cycle: investing in the training and development of dam professionals.

To see the full picture of the life cycle of a dam – all in one place – check out this article.

ABOUT THE AUTHOR

Joey Scicluna is a civil engineer with 6 years of experience across dam engineering, water infrastructure and project delivery. His work includes dam safety reviews, surveillance inspections, risk assessments, engineering analysis and the evaluation of dam performance and condition. Joey combines technical expertise with practical construction and project management experience, helping clients make informed decisions about the safety, performance and future management of their assets. He is particularly interested in finding practical solutions to complex engineering challenges and working collaboratively to achieve the best outcomes for projects and communities.

Life cycle of a dam – Phase 5: Upgrades – Renewing dams for a safe future

By Sally Fracalossi and Dr Shao Ng

A dam’s lifecycle moves through inception, design and construction, first filling and ongoing operation, surveillance and maintenance before, in most cases as needed, progressing to upgrade works. Upgrades may be needed because a dam is ageing, standards or knowledge have changed, or its operating environment and risk profile have evolved.

In this article, Principal Civil Engineer Shao Ng and Senior Civil Engineer Sally Fracalossi share their insights into the fifth stage in a dam’s life cycle, and how risk-based upgrades can efficiently improve dam safety and extend the useful life of existing assets.

An upgrade brings the dam life cycle full circle. The owner returns to investigation, options assessment, risk assessment, design and construction, but this time the project revolves around an existing asset that may need to remain operational throughout.

An upgrade typically aims to achieve effective life safety risk mitigation. It may respond to a specific failure mode, deterioration, operational or maintenance deficiency, new knowledge about floods or earthquakes, climate change, changing standards, increased downstream consequences, or the upgrade may be in response to an opportunity to change or extend the dam’s purpose.

Whatever the trigger, the task is to determine the interventions that will achieve the most meaningful improvements within the available resources and the complex realities of the site.

Understand the asset and the owner

Any upgrade should start with a clear understanding of the existing asset: how it was designed and constructed, how it has been modified, how it has performed and how conditions have changed.

Historical design information, surveillance records, instrumentation data, previous assessments and operational experience can reduce uncertainty and focus investigations on the issues that matter most. Good records are particularly valuable and should be supplemented by the institutional knowledge held by operators and dam safety personnel, as people and organisations change over a dam’s long life. Where the project team is unfamiliar with the dam, sufficient effort must be allowed to review its history, capture this knowledge and identify gaps requiring further investigation.

Understanding the owner is equally important. Not every owner has specialist dam expertise or knows from the outset what investigations or upgrade scope will be required. A good consultant must help the owner to identify and refine that scope, while ensuring the solution responds to the dam safety risk, the owner’s needs and the way the asset is intended to be operated.

Let risk drive the priorities

For dam owners who maintain a large portfolio of dam assets, a portfolio risk assessment can help identify which dams require priority attention, while a detailed risk assessment for an individual dam can identify the most significant failure modes and direct investment to where it will deliver the greatest benefit.

Once an intervention has been completed, the risk assessment can be updated to understand the risk reduction achieved, identify the remaining risks and determine whether additional measures could bring the residual risk to ‘as low as reasonably practicable’ (ALARP).

Stage risk reduction where appropriate

Staging can enable the most dominant risks to be addressed first, spread expenditure over time and allow information gained during early works to inform later interventions.

If an assessment identifies a critical or immediate risk, the first stage may be an interim measure that reduces exposure while a permanent solution is investigated, designed and delivered. Each stage should form part of an overall strategy, with a clear pathway to the permanent upgrade and appropriate management of the residual risks between stages.

Test constructability and affordability early

A technically sound upgrade design must also be feasible to build around an operating dam. Without sufficient construction input, a solution that appears fit for purpose during design could prove prohibitively expensive or difficult to deliver when tested by the construction market.

Formal early contractor involvement (ECI) can help the design team to examine access, construction methodology, sequencing, temporary works, plant requirements, materials and environmental controls during the early design stage while the design is still flexible. Where formal ECI is not appropriate, an experienced contractor or construction specialist can undertake a constructability assessment during design.

Construction activities can also introduce temporary risks that do not exist during normal operation. Excavation, dewatering, heavy plant movements and changes to reservoir operation should therefore be considered before works begin, with appropriate controls in place. At no stage during the construction should the existing dam risks be compromised.

Bring the owner and reviewers along

An informed design process should involve the owner throughout, not only at project initiation and final approval. At key stages, the design team should explain what is proposed, what the owner will receive, what uncertainties and trade-offs remain and whether the solution meets the owner’s needs. Concerns raised early can usually be addressed more effectively than concerns discovered at the final design stage.

Independent reviewers should also be engaged early and kept informed as design and construction progress. While remaining independent of the design team, they provide technical assurance by testing key assumptions, decisions and options against the project objectives and accepted practice. Their involvement helps identify potential gaps or concerns before they become embedded in the design or implemented on site.

Good outcomes are more likely when the owner, operators, designers, reviewers, regulators and contractors share an understanding of the project objectives through effective stakeholder engagement and are brought along as the solution evolves.

Protect and verify the design intent

The condition and configuration of existing dams can’t always be fully understood until elements are exposed during construction. Actual foundation levels, subsurface material properties, groundwater conditions or the condition of buried structures may differ from the assumptions made during design.

Some redesign during construction may therefore be unavoidable. Flexibility is appropriate where it responds to the conditions encountered, but decisions should not be made hastily due to the pressure of personnel and equipment waiting on site. Good engineering judgement combines responsiveness and flexibility with disciplined decision-making, documentation and communication.

Inspection and test plans, hold-point verifications, foundation mapping, test results, revised drawings and construction records provide evidence that the completed works meet the required quality and design intent. These records then become part of the dam’s permanent history and support future surveillance, maintenance and reviews.

Continue surveillance, monitoring and forecasting throughout the upgrade

Dam owners must continue monitoring and surveillance throughout the design and construction of an upgrade. These activities may need to be intensified where the works introduce temporary risks. Flood forecasting is crucial for managing the flood risk during construction, ensuring the safety of existing assets, construction workers and the public downstream, and protecting infrastructure and the environment from major flood damage.

After the upgrade is commissioned, the owner must review the surveillance regime and update inspection and monitoring requirements, operating procedures and the operation and maintenance manual to reflect the modified asset.

A dam will continue to evolve after its upgrade. Good records, updated operating documents and ongoing monitoring ensure that the knowledge gained during the upgrade project is not lost. The upgraded dam then becomes part of the continuing story as the dam moves into its next phase of safe operation.

UPGRADE PRINCIPLES IN PRACTICE: EDGAR DAM

Edgar Dam, in Tasmania’s south-west, forms part of Hydro Tasmania’s Gordon-Pedder hydropower scheme. The dam is located near Lake Edgar Fault and parts of the embankment are founded on fluvioglacial sandy gravels potentially susceptible to liquefaction. As understanding of the seismic risk evolved, Hydro Tasmania initiated investigations to quantify the risk and develop appropriate mitigation measures.

The resulting upgrade was the culmination of more than a decade of investigation, dam safety review, risk assessment, options studies, design and planning. Entura contributed geotechnical investigations, hydraulic and consequence assessments, surveying, GIS mapping, civil and structural engineering, environmental and planning support, detailed design and Principal’s Engineer services.

Constructability was a major consideration. The project involved dewatering ponded water at the downstream toe, excavating to bedrock, maintaining public road access and working in a remote location within the sensitive Tasmanian Wilderness World Heritage Area. The works had to balance dam safety, environmental requirements, site access and practical construction needs.

The solution involved removing the downstream concrete face, excavating to foundation level and constructing a filter and rockfill buttress to improve the dam’s seismic resilience. During construction, Entura’s geotechnical engineers inspected and mapped the excavations so that actual foundation conditions could be used to verify the design assumptions as the works progressed.

As Principal’s Engineer, Entura reviewed work methods, responded to requests for information, developed design changes and conducted inspections to witness and verify hold points. This allowed the team to respond to emerging conditions while ensuring the design intent and maintaining a clear construction record.

The completed upgrade significantly reduced the dam’s seismic risk within a tolerable level and improved the safety, reliability and resilience of Hydro Tasmania’s renewable energy infrastructure. The principal contractor, Hall Earthmoving, completed the works four months ahead of schedule in 2026.

UPGRADE PRINCIPLES IN PRACTICE: UPPER RESERVOIR DAM

Upper Reservoir Dam, near Hobart, is an 18 m-high puddle-clay-core zoned earthfill embankment constructed between 1885 and 1888. It is one of 3 dams in TasWater’s Waterworks System, together with Lower Reservoir Dam and Ridgeway Dam.

A 2017 dam safety review identified an unacceptably high risk of piping failure, principally associated with the outlet tunnel, together with a high risk of flood overtopping. The resulting assessment found that the societal and individual risks were unacceptable when assessed against the relevant ANCOLD risk guidelines.

TasWater adopted a staged approach to the upgrade. The first stage targeted the most dominant failure mode by constructing a localised filter around the outlet tunnel to reduce piping risk. The risk assessment was then updated to assess the reduction achieved and identify the next priorities.

The second stage addressed flood overtopping by raising the embankment crest. This also created an opportunity to incorporate a crest filter trench, providing additional protection against piping through the upper embankment. Considering the failure modes together enabled the planned works to deliver greater overall risk reduction in achieving ALARP.

Entura’s long involvement with Upper Reservoir Dam provided valuable continuity, including knowledge of its history, previous investigations, performance and earlier works. This helped the project team in identifying uncertainties and knowledge gaps, and focusing further investigation and design effort where it would add most value.

Entura supported the project through geotechnical investigations, hydrology and hydraulic assessment, heritage and environmental studies, stakeholder consultation, updated risk assessment, detailed design, tender support and construction supervision. Entura also served as Principal’s Engineer during the construction, providing technical support, construction verification and sign-off.

The Upper Reservoir Dam upgrade shows how detailed asset knowledge and a staged approach can help an owner to identify the dominant risks, act on the most urgent first and use each intervention to inform the next step in the dam’s ongoing improvement.

A further upgrade is currently underway, focusing on the reservoir’s outlet system.

In our next article in this series, we will consider the final stage in a dam’s life: decommissioning or repurposing.

To see the full picture of the life cycle of a dam, all in one place, read our overview article.

ABOUT THE AUTHORS

Sally Fracalossi is one of Entura’s senior dams engineers. She joined Entura’s Dams and Geotechnical Team in 2020, following 5 years in a multinational private consultancy where she gained broad civil engineering and project management experience. Sally is experienced in numerous aspects of dam engineering, including dam design, dam safety assessments and inspections, risk assessment and construction support. She has also been involved in developing dam safety emergency management plans, operations and maintenance manuals, and is actively involved in facilitating dam safety training as a certified trainer through the Entura clean energy and water institute (ECEWI).

Dr Shao Ng is a principal civil engineer at Entura and has almost 30 years of experience in civil and dam engineering in Australia and internationally. Shao has considerable experience in project management, dam design and construction, geotechnical investigations, inspections and surveillance reviews, emergency planning, and dam operation and maintenance. Shao also has extensive experience in dam portfolio risk assessment. His practical experience is complemented by 7 years as a lecturer in the School of Engineering at the University of Tasmania. He is highly regarded as a certified trainer with the Entura clean energy and water institute (ECEWI).

Life cycle of a dam – Phase 4: Operation – maintaining safety and value for decades

By Christopher Flack and Paul Southcott

The fourth phase in a dam’s life cycle is usually (and is intended to be) a very long period of operation, but it can never be ‘set and forget’. A dam may have been designed and built decades ago, but the responsibility of the owner to understand and manage its risks is always current.

In this article, Senior Civil Engineer Christopher Flack and Senior Principal Paul Southcott explain why active stewardship, risk-informed decision-making and continual investment in maintenance, people and preparedness are essential to keeping dams safe and reliable over the long term.

The operational stage of the dam life cycle is when the benefits (e.g. water supply, flood mitigation, recreation, etc.) of the dam continue to accrue after the large upfront capital investment has been committed. This phase of a dam’s life can last decades, and often much longer, but constant vigilance is required. Climate patterns and catchments change, downstream communities and industries develop, infrastructure ages, regulatory expectations increase, technology advances and workforces cycle. In all of this change, a dam owner’s challenge is to understand how risks are changing and ensure the dam continues to perform its primary functions safely and reliably.

Dam owners need to know how their dams are expected to perform, how they are actually performing, what could go wrong, what needs to be done before small issues become major risks, and how to manage emergency scenarios. Surveillance, maintenance, record keeping, training and emergency preparedness need to be integrated into a single risk-informed dam safety management system, rather than treated as separate activities.

Prioritise the biggest risks

Most dam owners’ resources are finite, so the key is knowing where effort, funding and attention will have the greatest impact. Portfolio risk assessments and regular reviews help owners understand failure modes, consequence profiles and relative priorities across their assets, which provides a sound basis for allocating resources and planning future work. Without a current understanding of portfolio risk, it becomes difficult to know whether surveillance programs are appropriate, whether maintenance budgets are being spent effectively, or whether recommendations for improvements and upgrades are targeting the most important issues.

Monitor what matters

The most effective monitoring and surveillance programs are developed considering potential failure modes and reviewed regularly. More data isn’t necessarily useful if it isn’t relevant or of good quality. What we’re looking for is reliable, targeted data that reveals emerging issues and long-term trends that tell us whether a condition is stable, seasonal, reservoir-level dependent or changing in a way that needs intervention. Telemetry, automated instrumentation and remote monitoring are good investments that can fill the knowledge gaps between routine manual inspections. When combined with engineering judgement, an effective monitoring and surveillance program will significantly improve understanding and enable earlier intervention.

Keep good records

Good records make dam safety reviews far more efficient and effective and reduce the uncertainty about how the dam is performing. Critical dam records come in many forms including design and construction reports, geological and geotechnical records, hydrometeorological records, consequence assessments, as-constructed drawings, photographs, inspection reports, surveillance data and monitoring data. All these sources help the reviewer understand what was built, why it was built that way and how it has performed since. Where records are missing, owners may need additional investigations, surveys, testing or analysis, often at greater cost and complexity because the dam is already operational.

Regularly review and update operations and maintenance manuals

Operations and maintenance manuals are equally important. They provide a clear reference point for operators, engineers and maintenance personnel, defining responsibilities, procedures, alarm thresholds and escalation pathways. One of the more common challenges across the industry is that these documents are not always reviewed and updated regularly enough to reflect changing conditions, renewal and modifications to the dam and evolving operational and organisational requirements.

Take a structured approach to managing recommendations

Inspection and assessment regimes generate recommendations for action that can accumulate into dozens or even hundreds for a single dam. But they’re no use if they’re buried in a spreadsheet or database that’s not managed and reviewed regularly. Important recommendations risk being overlooked among large volumes of outstanding (and possibly no longer relevant) items. It’s helpful to use a structured process to continuously review and consolidate recommendations, close out completed actions, identify duplication and prioritise work according to risk.

Invest in operators and staff

Well-trained, skilled people remain the first line of defence in maintaining dam safety. Effective maintenance and operation depend on operators having a good understanding of the value of their role, how the data they collect is used, what’s unusual, and when to escalate. Similarly, effective surveillance depends as much on experience, training and engineering judgement as it does on instrumentation and technology. Training should therefore be integrated into the dam safety management system. It should support surveillance activities, emergency preparedness and operational decision-making while also addressing longer-term workforce challenges such as succession planning and retention of institutional knowledge. It’s also not a ‘once and done’. Regular refreshers matter – and their frequency should be guided by level of experience and the risk position of assets.

Don’t underestimate routine maintenance

Seemingly simple actions – like vegetation management, drain maintenance, instrumentation upkeep, gate exercising, valve testing and maintaining safe access for inspections – can all be critical enablers of dam safety. Poor maintenance can obscure developing issues, reduce the effectiveness of inspections and compromise the reliability of important systems. Routine maintenance is often what allows operators and engineers to identify changes before they become significant problems.

Be ready for emergencies

Floods, earthquakes, equipment failures and dam safety incidents do happen – often without much warning. A dam safety emergency plan should clearly set out who does what, when decisions need to be made, how response levels escalate, and how communication occurs with emergency services, regulators, operators, the media and affected communities. It also needs contingency plans for power outages, communications failures, SCADA outages, limited site access, fatigue, backup resources and alternative means of communication. Because conditions around a dam are always changing, the emergency plan must be updated regularly and stress-tested through exercises.

Promote public safety around the dam

Dam safety risks are not limited to failures of the dam structure. Public safety risks include falls, swift currents near intakes and spillways, sudden water level changes, turbulent flow and hazardous hydraulic conditions around structures such as low-head weirs. Operators should take a practical approach: site-specific risk assessment, clear responsibilities, physical barriers where needed, effective signage, audible or visual warnings, public education, staff training, incident reporting and periodic review.

Read our articles:

• Planning for the future – the challenges of dam inspection and maintenance
• Safer dams are a matter of priority
• Portfolio risk assessment takes dam safety programs to the next level
• What can dam owners do to better manage floods and avoid the blame game?
• How robust is your emergency preparedness?
• Keeping close tabs on your dams

• Keeping safe around dams
• Are you investing in your most valuable asset?
• Making more of your monitoring

Operational principles in practice: TasWater’s dams portfolio

TasWater’s dam safety journey demonstrates how these principles work together in practice. Following the consolidation of Tasmania’s regional water authorities and council-owned water assets, TasWater inherited a diverse portfolio of dams with varying levels of available information about condition, performance and risk.

To establish a consistent understanding of risk, Entura undertook portfolio risk assessments, quantifying potential failure modes, updating consequence assessments and providing risk-informed priorities for future investment.

To improve operational visibility, Entura subsequently reviewed, designed and implemented upgraded monitoring systems across multiple Tasmanian storage sites, including instrumentation improvements, telemetry solutions and data collection systems aligned with contemporary dam safety guidance.

Those improvements supported a broader surveillance and dam safety program that included intermediate inspections, comprehensive surveillance reviews, deformation surveys, specialist instrumentation monitoring, updates to operation and maintenance manuals, updates to dam safety emergency plans and support for risk-based prioritisation tools.

Our registered training organisation, the Entura clean energy and water institute (ECEWI), delivered operator training to TasWater personnel through classroom learning, field inspections and workplace-based assessment, helping operators understand not just what information to collect, but why it matters and how it supports decision-making. The training was delivered to multiple cohorts and contextualised to TasWater’s own procedures, templates and reporting tools.

This range of activities is a great example of an integrated dam safety program: assessing the portfolio risk, upgrading the monitoring, inspecting and interpreting performance, maintaining good records and procedures, and training people. Each element strengthens the others. Together they create a practical framework for keeping dams safe, reliable and resilient over the long term.

In our next article in this series, Principal Civil Engineer Shao Ng and Senior Civil Engineer Sally Fracolossi will share their insights into the fifth stage in a dam’s life, showcasing a number of dam upgrades.

To see the full picture of the life cycle of a dam – all in one place – check out this article.

ABOUT THE AUTHOR

Christopher Flack is a Senior Civil and Dams Engineer with technical depth, practical site experience and strategic project leadership in dam safety, design, risk assessment, surveillance, construction and asset management. He has acted as project manager and lead author on numerous surveillance programs and dam safety reviews for clients across Australia, consistently ensuring high-quality outputs, sound engineering judgement and effective client engagement. Chris has also been design manager and technical lead on major dam upgrade and design projects, including Pet Dam and Bronte Dam upgrades in Tasmania.

Paul Southcott (Senior Principal – Dams and Headworks) is Convenor of ANCOLD’s ‘Guidelines for Dam Instrumentation and Monitoring Systems Working Group’. He has nearly four decades of experience in civil and dam engineering, with an exceptional depth of technical knowledge and extensive industry experience. Paul’s expertise is a crucial part of Entura’s ongoing support for dam upgrade and safety works for our clients’ extensive dam portfolios. He has contributed to many major dam and hydropower projects throughout Australia and the Indo-Pacific region, including for Hydro Tasmania, TasWater, Snowy Hydro and numerous councils and water utilities including SeqWater, Sun Water and SAWater. Paul was named Tasmania’s Professional Engineer of the Year in Engineers Australia’s 2021 Engineering Excellence Awards.

Life cycle of a dam – Phase 3: First filling – When a dam is tested for the first time

By Richard Herweynen

A dam’s life cycle moves through inception, design and construction through to operation and maintenance, and potentially to upgrades, decommissioning or repurposing.

In this article, Entura’s Technical Director Water, Richard Herweynen, shares his insights into the important third stage in a dam’s life – first filling – with examples from Malaysia and Queensland.

The first filling is an exciting milestone in the life of a dam but it is also one of the highest-risk stages. It is the first time the design assumptions, construction quality, foundation conditions, materials, instrumentation, operating systems and dam safety processes are tested together as a system under real water load.

In this sense, first filling sits on the high-risk side of the ‘bathtub curve’, where risk is highest at the beginning of a dam’s life and at an advanced age. However, with clear governance, well-targeted and well-functioning instrumentation, close surveillance and robust emergency preparedness, any unexpected behaviour can be detected early and investigated and managed appropriately.

Following the principles below, first filling should be a carefully managed and observed confirmation that the dam is performing as expected.

Determine readiness to impound

As construction concludes, the design manager or responsible engineer will undertake a final inspection to confirm that all engineering works have been completed to the required standard. This includes civil works, mechanical and electrical systems, outlet works, instrumentation, closure arrangements and any other systems needed for safe impoundment. Non-conformances need to be closed out or accepted through an appropriate engineering process, and the documentation needs to support the conclusion that the dam is ready to fill.

To gain a regulator’s approval to impound a reservoir, the dam owner will need to demonstrate that all relevant engineering conditions have been satisfied as well as any environmental, social and regulatory conditions.

Apply a risk-based framework to the readiness to impound assessment

Using a structured risk-based framework for the readiness to impound assessment, ensures that the attention is focused on the issues that matter prior to impoundment occurring.

The action list, often supported by a simple traffic-light system, can help owners, designers, regulators and contractors clearly understand and communicate what remains to be done, what is acceptable, and what must be resolved before filling begins. It provides a transparent and defensible basis for deciding whether a dam is ready to impound.

Check instrumentation and behaviour

First filling is the first opportunity to compare the dam’s actual performance with the behaviour predicted during design – which makes instrumentation a core focus. Before impoundment, the required instruments need to be installed, commissioned and functioning well. Depending on the dam type and the risks that need to be monitored, instrumentation may include piezometers, seepage measurement devices, deformation monitoring, settlement points, uplift pressure monitoring or other systems that are relevant to the dam’s potential failure modes. The key is not simply to collect data, but to ensure that the data is meaningful and demonstrates the dam’s actual performance as the reservoir rises.

If the dam behaves as expected, confidence grows that the design assumptions and construction outcomes are sound. Data that deviates from expectations should trigger investigation. The design engineers need to understand why the readings are different and whether any additional monitoring or responses are needed.

Seepage from an embankment dam is a good example. If seepage is observed during first filling, it’s not necessarily a cause for immediate alarm, but it must be monitored and investigated. If the seepage stabilises and remains clear, ongoing monitoring may be enough, perhaps with extra instrumentation added. If seepage increases, becomes cloudy, or is associated with movement or other concerning signs, it may indicate internal erosion, the early stages of a piping failure mechanism. In that case, a more active response is likely to be needed.

Be prepared with dam safety emergency planning

A well-designed and well-constructed dam should fill safely. However, dam engineers are inherently conservative which is appropriate, given the consequence of dam failure can be catastrophic. This is why emergency preparedness must be in place before impoundment begins.

A dam safety management plan should set out how the dam will be operated, monitored and inspected during first filling. This must clearly identify a designated dam safety manager or other responsible person. A dam safety emergency plan should also be prepared, with defined trigger levels, roles, communication pathways and escalation processes. Although there is a high expectation that the dam will perform as designed given the systems and process adopted in Phase 2 of the dam’s life, it is important to be prepared for all scenarios as this is good dam safety practice.

In practice, potentially concerning observations may move through stages of response. A minor anomaly may trigger internal review and closer monitoring. A more serious or deteriorating issue may trigger expert inspection and intervention. If the situation reaches an emergency threshold, the emergency plan must be ready to activate, including communication with emergency services and downstream communities if required.

Develop a comprehensive first filling report

At the end of first filling, good practice is to prepare a detailed first filling report. This report records what was expected, what actually happened, how the dam performed, what anomalies were observed, how they were assessed, and what baseline conditions should inform future surveillance. The first filling report is an important handover into the next stage of the dam lifecycle: operation. It provides the reference point for future inspections, instrumentation reviews and surveillance reports.

PRINCIPLES IN PRACTICE: MURUM DAM, MALAYSIA

Murum Dam is a 146 m-high roller-compacted concrete dam in Sarawak, Malaysia, and forms part of the 944 MW Murum Hydropower Project. Entura was engaged by the regulator as independent dam safety engineer to provide a holistic assessment of the dam’s readiness to impound.

Entura’s role covered the pre-impoundment, impoundment and post-impoundment stages. The team reviewed design and construction documentation, inspected the site, identified potential failure mechanisms, and we used a risk framework to identify and prioritise key dam safety issues that needed to be addressed before impoundment could begin.

The process separated critical items from less critical items. Activities essential for safe impoundment were tracked, including physical works, dam safety systems and processes, instrumentation and emergency preparedness. Less critical items were also tracked, but were not necessarily conditions for commencing impoundment.

The risk framework helped us clearly communicate progress to the regulator for the dam’s readiness to impound. We could rate items according to their status, making it clear what remained unresolved, what was acceptable for filling, and what had been completed. Once we were satisfied from a dam safety perspective, we informed the regulator that we believed the dam was ready to impound. The regulator then considered other matters, including social and environmental issues outside Entura’s scope, before approval to impound was issued.

Murum’s reservoir took more than a year to fill, and we remained involved through first filling and into the first year of operation. Site visits and instrumentation reviews confirmed that the dam was performing as expected. At the end of that period, the dam could move into the owner’s ongoing portfolio management arrangements with confidence that it had passed through the first filling stage safely.

PRINCIPLES IN PRACTICE: WYARALONG DAM, QUEENSLAND

Wyaralong Dam in south-east Queensland was developed to improve water storage and contribute to long-term reliable water supply for the region. Entura was part of the alliance that designed the 50 m-high, 490 m-long roller-compacted concrete dam, which includes a centrally located ungated primary spillway, a stilling basin, a secondary spillway, outlet works and a fishway.

For first filling, the process followed a typical pathway from construction completion into formal impoundment approval. During construction, a design representative was on site full time to take care of any design changes as a result of actual conditions, ensure that the design was constructed in accordance with the specifications, and address any non-conformances identified. As design manager and the responsible Registered Professional Engineer Queensland (RPEQ), I signed off that the design-related requirements had been met and the dam had been constructed in accordance with the design. This included confirming that construction issues and non-conformances had been closed out, systems were in place, instrumentation was installed and operating, and the dam was ready to be closed and filled. That sign-off formed part of the submission to the regulator.

Unlike Murum, Wyaralong filled very quickly. Floods occurred soon after filling began, and within about a month the dam was spilling. This meant the dam was tested not only by first filling, but also by spillway operation very early in its life. We captured this performance in the first filling report and established a baseline for ongoing operation and surveillance.

Wyaralong shows how first filling can quickly become more than a gradual reservoir rise. Natural inflows may accelerate the process and test multiple parts of the dam and its operating systems sooner than expected. This reinforces the importance of having the engineering sign-offs, instrumentation, surveillance processes and emergency arrangements ready before impoundment starts.

In our next article in this series, Senior Civil Engineer Chris Flack will share his insights into the fourth stage in a dam’s life: the long period of safe operation and ongoing maintenance.

To see the full picture of the life cycle of a dam – all in one place – check out this article.

ABOUT THE AUTHOR

Richard Herweynen is Entura’s Technical Director, Water. He has more than 3 decades of experience in dam and hydropower engineering, working throughout the Indo-Pacific region on both dam and hydropower projects. His experience covers all aspects including investigations, feasibility studies, detailed design, construction liaison, operation and maintenance, and risk assessment for both new and existing projects. Richard has been part of a number of expert review panels for major water projects. He participated in the ANCOLD working group for concrete gravity dams and was the Chairman of the ICOLD technical committee on engineering activities in the planning process for water resources projects. Richard has won many engineering excellence and innovation awards (including Engineers Australia’s Professional Engineer of the Year 2012 – Tasmanian Division), and has published more than 30 technical papers on dam engineering.

Life cycle of a dam – phase 2: development – turning a preferred option into a reliable dam

By Tim Griggs

As we’ve discussed previously, a dam’s life cycle moves through inception, development, first filling, operation, upgrade/improvement and eventually decommissioning or repurposing.

The development phase expands the investigation and design begun in the inception phase, resolving all the necessary details for construction. It results in a constructed asset, ready for Stage 3: first filling.

In this article, Principal Civil Engineer Tim Griggs shares his insights into the second stage in a dam’s life, and how a rigorous development phase led to the successful completion of Meander Dam in Tasmania, which is owned and operated by Tasmanian Irrigation.

Once a dam project moves beyond the inception phase, the need has been identified, the site has been selected and the preferred option has enough confidence to proceed. The next phase, development, is where the site-specific risks identified during inception are properly understood, where a concept becomes an engineered solution, and where that solution is built to the standard the community will rely on for the next 100 years and beyond.

The big questions at this stage are managing risks, resolving the fine details of how the dam should be engineered and constructed, and ensuring that the design intent will be achieved on site. This sets a dam up for success in Phase 3 (first filling) and Phase 4 (operation).

Extend the understanding of the site

There’s no universal answer to what type of dam suits a given location. This emerges from the hydrology, geology, topography, the materials available, the hazard category and the construction constraints of that particular site. In the inception phase of the project, the preferred site and option will be identified. The development stage then tests the preferred option against the physical reality of the site.

Earlier planning should have identified the most important geological questions but will usually have avoided gathering unnecessary detail too early. Development must now unearth the right detail in the right places to reduce the uncertainties that matter – like those affecting potential failure modes and therefore the safety of the dam, cost, constructability or long-term performance. The resulting geological model informs potential failure modes, stability analysis, foundation treatment, seepage controls, excavation requirements, material selection and construction sequencing.

Consider the realities of construction

A design that’s appropriate for the site and geology and that meets the relevant standards and minimises the risk position still needs to be buildable. Some of the most valuable decisions in development are those that simplify sequencing, reduce construction risk, shorten the program, improve quality control or take work off the critical path.

Design should anticipate the realities of construction, with its dependence on weather, river diversion, site access, safety of personnel, availability of plant and materials, placement rates and quality assurance. Careful consideration of these factors early in design is more likely to result in a safe, timely, cost-effective and quality build.

Optimise and innovate to improve construction and performance

Ideally, the designer and constructor should work together to identify and implement solutions that optimise the design to improve construction outcomes. The constructor provides key inputs on cost and time savings that are integral to making such decisions to modify the design.

Similarly, the eventual dam operator should be consulted and modifications made to ensure efficient operation and maintenance over the dam’s life cycle. Formal reviews, such as hazard and operability reviews, can facilitate such input.

Design to standards and for resilience

Dam design must keep pace with evolving standards, guidelines and leading practice – however, climate change adds a new level of uncertainty. Extreme flood estimates should be treated as an uncertainty band rather than a single value. Dam designers need to make assumptions clear, test sensitivity and build in resilience where future conditions may change the risk profile. Dam owners should be consulted to ensure they are comfortable with the assumptions made.

Understanding the specific hazards for the particular dam site is important because the design of a dam needs to be robust and be able to withstand these hazards during the dam’s life.

Ensure sound technical governance

Regardless of a dam’s size or profile, sound technical governance during design and construction is crucial. An independent review panel will challenge assumptions, probe key risks and help the project team avoid blind spots – focusing on the matters that most affect dam safety, performance and constructability. Common focuses include geological uncertainties, use of unproven materials or technology, and any proposed changes during the construction phase.

The level of conservatism and technical scrutiny should be shaped by the risk profile of the dam, including the potential consequences of failure, flood hydrology, foundation conditions, seismic loading, operational requirements and downstream context.

It’s crucial for the independent review panel to include the right mix of specialists who are engaged early and maintained through to the end of construction, properly briefed, aligned in their understanding of the project objectives and the panel’s scope, and able to communicate effectively.

Provide the right people on site during construction

Having the right experience on site –  people who have experienced it all before – isimportant for ensuring that construction methods are suitable and appropriate actions are taken to rectify any issues.

It’s also important to maintain a degree of continuity from design to construction, with some design support present throughout the construction phase. This ensures that appropriate action is taken when the conditions on site are different from the design assumptions and that non-conformances where works don’t meet the required specifications are resolved.

Make construction quality visible and traceable

Quality assurance in construction provides evidence that the constructed asset meets the design intent. This requires clear specifications, inspection and test plans, materials testing, compaction controls, records of foundation treatment, verification of lift joint quality and proper management of any departures from design.

Disciplined recording of quality assurance during construction is crucial for later stages of the dam’s life – including first filling, operation and maintenance, future assessments and long-term dam safety management.

Provide a suitable level of monitoring that targets key failure modes

Instrumentation design for a new dam should be based on the identified failure modes for the asset. Dam instrumentation needs to be designed so that it tells you what you need to know. This will be critical for validating the design and construction during first filling, where instrumentation can demonstrate that the dam is (or isn’t) performing as expected.

DEVELOPMENT PRINCIPLES IN PRACTICE: MEANDER DAM

Meander Dam in northern Tasmania demonstrates these principles in action. It is a 50 m-high, 43,000 ML roller-compacted concrete dam owned and operated by Tasmanian Irrigation. It was built between 2005 and 2007, with Entura involved from feasibility through to construction completion.

The site itself drove many of the key design decisions. The dam is located in a relatively narrow valley on the Meander River and is founded entirely on dolerite: a hard, high-strength rock that is jointed and locally weathered along joint planes. Those conditions supported the selection of a concrete gravity dam using roller-compacted concrete (RCC) that would allow significant floods to be passed through a central spillway rather than needing a large excavation into a steep abutment for a side spillway.

The geological investigations examined the access road alignment, dam footprint, reservoir area and availability of construction materials. Investigations identified that dolerite quarried near the left abutment could supply the RCC aggregate, though achieving a well-graded mix from the dolerite crushing operation proved more difficult than expected, requiring the aggregate to be supplemented with crusher dust to meet the specification.

The use of RCC allowed a more economic river diversion strategy (as the partially completed dam could be overtopped) and a faster construction program (as RCC can be placed rapidly using earthmoving-style plant rather than the slower cycles of conventional mass concrete).

A dambreak and consequence assessment also fed into the development phase. This established Meander Dam’s consequence category under the ANCOLD guidelines, which in turn shaped the level of conservatism applied throughout design and the design flood requirements.

Design at Meander Dam followed ANCOLD’s Guidelines on Design Criteria for Concrete Gravity Dams, with stability checked against normal, unusual and extreme load combinations – including floods up to the Probable Maximum Precipitation Design Flood (PMP DF) and a 0.2g maximum design earthquake. Seasonal flood frequency data for the 160 km² Meander River catchment was integral to the sizing of the upstream and downstream cofferdams.

Meander Dam’s design also considered optimisation of the general arrangement to best pass large floods. A 60 m-long secondary spillway was incorporated on the right abutment (overtopping in a 1:100 AEP event), which reduced peak flood levels and therefore the height (and cost) required of the abutments – while still allowing the dam to safely pass a PMP design flood peaking at 2,630 m³/s.

The independent reviewer played a key role in the design process and ensured that decisions were challenged appropriately. This included a detailed review of the selection of a PVC membrane most suited to installation and ongoing performance on a vertical upstream face.

A number of other construction-focused innovations were built into the design. Precast upstream panels acted as permanent formwork, speeding construction. An external, exposed geomembrane allowed RCC placement to continue without interrupting the critical path. Precast L-shaped downstream blocks doubled as spillway formwork and a durable, stepped downstream face. A conveyor delivery system on the left abutment helped minimise the time between batching and placement so the RCC could be spread and compacted within its workable window.

Each of these features was a direct response to a risk or a construction constraint identified earlier in the development phase, whether that was foundation geology, program, cost or lessons carried over from previous projects.

Phase 2 at Meander Dam ultimately turned a preferred option into a reliable asset. Construction was completed in 2007 and the dam continues to support reliable irrigation supply in the Meander Valley.

In our next article in this series, Technical Director Richard Herweynen will share his insights into the third stage in a dam’s life, and the first filling of Murum Dam in Malaysia and Wyaralong Dam in Queensland.To see the full picture of the life cycle of a dam – all in one place – check out this article.

ABOUT THE AUTHOR

Tim is a Principal Civil Engineer at Entura with 30 years of experience in hydropower and dams across the full asset lifecycle, including feasibility, preliminary and detailed design, construction and ongoing operation and maintenance support. His experience in roller-compacted concrete dams is highly regarded. Tim’s projects span Tasmania, mainland Australia, Malaysia, Philippines, Papua New Guinea, Uganda and Costa Rica. He leads multi-disciplinary teams and delivers complex projects that contribute to water security and the energy transition. Tim shares his expertise in technical papers, conference presentations and thought leadership articles. He mentors young professionals and promotes strong international working relationships. 

Life cycle of a dam – Phase 1: Inception – Setting a dam project up for success

By Jaretha Lombaard

A dam’s life cycle moves through inception, design and construction through to operation and maintenance, and potentially to upgrades, decommissioning or repurposing. In this first article in our forthcoming ‘Life cycle of a dam’ series, Senior Civil Engineer Jaretha Lombaard shares her insights into the important first stage in a dam’s life, and how a strong inception stage has shaped a new pumped hydro project proposal.

Infrastructure’s ability to successfully serve communities for generations depends heavily on good beginnings. To me, a ‘good beginning’ for dam-specific projects looks like this:

Know your ‘why’

The first step in any infrastructure project is usually to clearly define needs, objectives and key benefits. In the case of water and energy infrastructure, the need may be residential, industrial or environmental water supply, irrigation, flood mitigation, river regulation, energy generation and storage, or a combination. Once the need is clear, we should explore the best way to meet the need – rather than assume that a dam is necessarily the right answer. If the ‘why’ is unclear, momentum can build around a technical solution before the real objective has been tested. When the ‘why’ is clear, every subsequent decision has a stronger basis.

Start broad

If the right answer is a dam, we now need to probe deeper – from the ‘why’ to the ‘where’, ‘how’ or ‘what’. This is the time to brainstorm a range of high-level options and then investigate whether they’re technically feasible, practical and capable of meeting the project’s objectives. How much water, energy storage or flood mitigation is required? How often must water or energy be available? Should we be considering a smaller or larger storage, an off-stream storage or a multipurpose project? Where could the dam be located? What type of dam could suit the available sites? Can the project be safely constructed? What are the main environmental and social constraints, and the possible risks?

Align multidisciplinary expertise

Engineers should work alongside geologists, hydrologists, environmental scientists, ecologists, heritage and social specialists and dam safety practitioners from the earliest stages so that potential impacts can be identified early and addressed right from the start. The planning and concept stages have the greatest influence on a project’s long-term outcomes. This is when decisions about site selection, dam type, reservoir level, spillway configuration, operational rules and mitigation measures are still open to improvement. Once the project moves into later phases, changes become more constrained and often more costly to implement.

Engage stakeholders early

Stakeholder alignment should always begin early to confirm the need, identify constraints and priorities, reveal local knowledge and alternative ideas, and test whether options are likely to be acceptable. Some stakeholders may seem less prominent at first but could become highly influential if their needs or concerns are missed. Once stakeholders are aligned, it’s important to ensure transparency and ongoing communication to build and maintain trust.

Gather the right level of information at the right stage

Options need to be developed to a comparable level. Too little information makes meaningful comparison difficult. Too much detail wastes effort on options that may not proceed. The focus should be on the factors most likely to determine the preferred option, such as technical feasibility, environmental and social impacts, constructability and approvals risks. Effort should be spent where and when it will make the biggest difference to the outcome. This means focusing on the key knowledge gaps and risks that will drive the technical feasibility, cost, delivery timelines, and stakeholder acceptability.

Carefully size and stage investigations

Geology and geotechnical characteristics are key inputs for early decision-making around technical feasibility and cost of a dam project, but the timing and scale of investigations need to match the maturity of the project. A staged investigation program may begin with desktop geological and topographical reviews, engineering geology site walkovers, and non-destructive, low-impact methods such as geophysical surveys and geological mapping. As the options narrow, more intrusive investigations such as test pitting and drilling can be targeted where they will provide the most value. Drilling too early can create its own problems. If too many options are still under consideration or general site conditions area not yet well understood, investigations may need to cover a very large footprint, which means more cost and more disturbance. A staged approach helps balance decision-making needs, investigation costs, and risks by progressively refining the understanding of site conditions as the project matures.

Use a consistent, defensible method to compare options

A structured, risk-based multi-criteria analysis can help compare options more transparently by keeping material risks visible. High risks should not disappear within averaged or low weighted scores. Decision-makers need to see the trade-offs clearly, especially where environmental, social, technical and financial considerations point in different directions. The strongest options are usually those that perform consistently across multiple criteria. They may still have uncertainties, but those uncertainties are understood, recorded and can be effectively managed.

Keep good records

Dam projects often span many years, during which project teams, stakeholders and decision-makers, as well as regulations, can change. A well-maintained record of decision-making is essential. It provides transparency and rationale around why options were excluded, preferred pathways selected and constraints addressed, including the risks, uncertainties and opportunities that influenced those decisions. It also reduces the likelihood of revisiting issues that have already been assessed.

Involve independent reviewers early

An independent reviewer or review panel can be one of the most valuable contributors during project inception and development. The individual or panel should have the right balance of technical expertise, be able to communicate well in a collaborative manner, understand their scope of work and be well briefed. An early and ongoing engagement enables reviewers to develop a strong understanding of the project’s original ‘why’s, ‘what’s and ‘how’s, enabling them to provide informed advice and constructive challenge throughout project development.

Don’t try to do everything at once

Not every detail needs to be resolved to 100% when comparing potential options or even once the preferred option has been established. That resolution and optimisation can happen in the ‘detailed design’ phase, which we’ll talk about in our next article. However, by the end of the preliminary design or ‘reference design’, the preferred option should be workable, costable and suitable for approvals and investment decisions, with the key aspects robust enough for the project to move forward with confidence.

INCEPTION PRINCIPLES IN PRACTICE: THE PROPOSED CETHANA PUMPED HYDRO PROJECT

The proposed Cethana pumped hydro project in Tasmania is a large energy storage project with a generating capacity of 750 MW and a storage capacity of 20 hours. It proposes using the existing Lake Cethana as the lower storage and building a new upper storage, underground power station, and underground tunnels connecting the storages. If approved, it will be the first pumped hydro project in Tasmania.

The inception phase of the project demonstrates how the principles discussed in this article have been applied in practice.

Entura contributed to the prefeasibility and feasibility studies that identified 14 possible pumped hydro sites in Tasmania and narrowed these to the three most promising, and then to Lake Cethana as the preferred option for final feasibility. The options were assessed against technical, environmental, social and economic factors using multicriteria analysis. The Lake Cethana option was selected as the preferred project option because it offered deep storage capacity, greater cost certainty, less potential environmental and social impacts, and more flexibility in sizing and capacity.

By the time I became involved, the upper storage site had already been selected, but there were still aspects to resolve. My focus was on revising the layout and embankment material zoning of the upper storage so it could best fit the available space, reduce the environmental impacts, balance cut and fill volumes, reduce spoil, preserve the required storage volume and hydraulic head, and maintain efficient flow to the intake.

An understanding of the geology and geotechnical conditions was central to refining the layout and internal embankment zoning. Some areas included highly compressible soils which directly informed the quantity of material to be excavated and spoiled, the construction phasing required to limit post-construction settlement to acceptable amounts, and ultimately construction cost estimates.  

The outcome was a reference design for the upper storage that supported the overall project cost estimate, based on available information, and provided a clearer understanding of the key considerations for the next stages of design.

The team did not need to solve everything at this stage of the design, but it did need confidence that the main concept would work. For example, the project needed a technically sound and workable approach to lining the storage, maintaining the liner, monitoring performance and detecting potential leakage. Although some opportunities for improvement were carried forward to the future stages of the design process, the fundamentals needed to be strongly in place at this stage.

This is the purpose of inception: It should move a project from a broad need to a robust and defensible preferred option. At its core, inception is about progressively reducing uncertainty, allowing decisions to be made with increasing confidence while keeping options open long enough to identify the best path forward. When done well, it provides owners, stakeholders and reviewers with confidence that the project is worth taking forward.

In our next article in this series, Principal Civil Engineer Tim Griggs will share his insights into the second stage in a dam’s life and how a rigorous development phase led to the successful completion of Meander Dam.

To see the full picture of the life cycle of a dam – all in one place – check out this article.

ABOUT THE AUTHOR

Jaretha Lombaard is a senior dams engineer with more than 12 years of diverse experience across southern Africa and Australia. Her expertise includes dam design, tender and construction support, dam safety assessments and inspections, with a strong focus on safe, sustainable infrastructure. Since joining Entura, she has contributed to major projects including as design manager for major dam upgrades. She is highly regarded for her commitment to technical excellence, leadership, proactive problem solving and collaborative delivery. Passionate about best practice, continuous improvement and professional growth, she actively supports mentoring, knowledge sharing and training.

Making more of your monitoring

Monitoring dams is a key aspect of dam safety, but what do we mean by monitoring, why is it necessary, and how can dam owners make the most of their monitoring investment? Senior Principal Paul Southcott shares his insights …

Dam safety is a system that responsible dam owners put in place to protect the community, environment and infrastructure. Monitoring is an important element of this system. By monitoring we mean using instrumentation to help assess the condition of the dam and detect early signs of deterioration so that action can be taken to address the issue.

Here are some principles for getting the best value from your investment in dam instrumentation:

Monitoring across the dam lifecycle

Exactly which instruments need to be considered will depend on both the stage of the dam’s life the type of the dam. For example, at the concept stage, rainfall and stream gauges in the catchment will provide key data on the hydrology including flood estimation and yield. Similarly, during construction of an embankment dam, settlement cells may be used to measure the deformation of fill as the dam is built. There may even come a time in the dam’s lifecycle when certain instruments no longer provide relevant data to the dam owner. This article focuses on the operation stage of the dam, but the same principles apply regardless of the stage of the dam lifecycle.

Measuring the right things in the right places

Instrumentation is fundamentally about measuring a parameter associated with dams – such as seepage, pressure or movement – that tells us if the dam is behaving as the designer intended or if some investigation and/or intervention is required. To decide what instruments to install and where to locate them, the key thing is to measure the parameters linked to the potential failure modes (PFM) of the dam. This reveals when early intervention is needed to prevent failure or to trigger emergency actions through the Dam Safety Emergency Plan (DSEP).

To understand the PFMs of a dam, we must first undertake a risk assessment that considers all the potential ways that the dam can fail. The next step is to consider which parameters could be measured to give warning of that particular failure mode. For example, if the failure mode was flood overtopping leading to erosion and breach of an embankment dam, then measuring rainfall and reservoir level would be appropriate. Rainfall would warn that a flood is coming; reservoir level measurements would reveal how close the dam is to being overtopped. Both forms of instrumentation would be useful: rainfall as a lead indicator that conditions are changing and reservoir level as an indicator of current conditions and whether actions need to be taken (e.g. opening spillway gates or starting emergency evacuations).

Other PFMs would require different types of instruments to detect incipient failures. For example, piping or internal erosion is often a key failure mode of earthfill and earth and rockfill dams. The best instrument to detect this failure mode is a seepage monitoring weir, often using a v-notch weir. This instrument captures and measures the seepage rate by measuring the water level behind the weir, which can then be converted to an equivalent flow. The trend in the readings over time will indicate whether seepage is stable or is showing an increasing trend that may indicate an emerging piping failure. Location of the weir is critical: it needs to be located so that it captures all the seepage from the dam (or part of the dam) but is not so far downstream that there is a significant catchment highly influenced by rainfall runoff.

Installation and commissioning

To make sense of instrument data, we need to know exactly where the instrument is installed and what it is installed in, and be confident that we have the right calibration certificates. This is why a detailed quality assurance process needs to be in place for installing and commissioning instruments.

Consider the installation of a vibrating wire piezometer in the rock foundation of a concrete gravity dam to measure the uplift pressures under the dam. Installing the piezometer will require drilling a hole into the rock, lowering the piezometer down the hole, surrounding it with a backfill material and sealing it into the hole, running the cable to a data logger and programming the data logger. Each step could affect the instrument’s ability to provide meaningful data for review and analysis:

• Drilling the hole: Soil and rock foundations are typically heterogeneous (not uniform), so the instrument’s location will affect its readings (a piezometer installed in solid rock will not record anything, whereas installation in closely jointed rock may record close to reservoir pressure). Geotechnical logging of the hole is recommended so that the instrument can be installed where it will capture the most relevant information and to assist in interpreting the data.
• Installing the instrument: The level of the instrument must be recorded correctly because it is critical to both the calculation of the foundation pressure and the associated interpretation of the data. Similarly, before installation, the instrument needs to be correctly identified by recording its serial number (and associate calibration certificate), and its function must be checked with a zero reading obtained.
• Sealing the instrument in the hole: Sealing the hole prevents it becoming a drain (i.e. providing pressure relief), but will also prevent removal of the instrument in the future, which is why a quality assurance process should first confirm that the instrument is functioning appropriately.
• Running the cables: Cables must be correctly identified to ensure the instrument is correctly identified at the data logger. This is particularly important when many instruments are being installed at the same time.
• Programming the data logger: It is easy to incorrectly program the data logger to convert the raw data (a frequency measurement in vibrating wire instruments) to either a pressure or head value. The raw data should be recorded and saved in the long-term database so that it can be checked and validated by manual instrument readings.

Checking the data

Getting data is not enough; the data needs to be good. Instruments can tell us a lot about how a dam is performing, but all instruments fail eventually and their calibration needs to be checked regularly. Ideally, this should be done using an independent instrument that can be read manually. For example, many different instruments can measure the water level in a reservoir. It is very easy to check they are providing good data by having gauge boards in the reservoir set to the same datum that can be read by operators during routine inspections and then cross-checked against the data received from the electronic instruments and data loggers. If there is an anomaly between readings, the cause of the data error needs to be tracked down and fixed.

Data storage

Data loggers have limited data storage capacity and typically overwrite old data if the data is not downloaded frequently enough. A secure database is needed to ensure that the full record of monitoring data is available for the life of the structure. Retaining the full record allows long-term trends to be identified and investigated.

Review and interpretation

Collecting and storing monitoring data is only the beginning. To make it a useful dam safety tool, the information needs to be regularly reviewed and interpreted. This will typically involve generating timeseries plots of the parameters against environmental data (e.g. rainfall and temperature) and loading data (e.g. reservoir level). The purpose of monitoring is to check that the dam is not exhibiting signs that may be an early indicator of a potential failure mode.

For example, seepage monitoring data from an embankment dam is a key way of monitoring for initiation of a piping or internal erosion failure mode. Seepage is influenced by both reservoir level (as this influences the seepage rate through the embankment and foundation) and rainfall (adding to the flow through the monitoring weir from rainfall runoff). Interpretation of the plots is not simple. A step change or a gradual change over years may indicate an emerging safety issue and should be investigated further. Sometimes the scatter in the data is hard to resolve, but a scatter plot of one variable against another (e.g. plotting seepage against reservoir level) can help untangle the key influences and relationships between parameters. 

Monitoring data can also highlight potential safety issues when compared against the design assumptions and expectations. A common example is comparing the actual foundation pore pressures below a concrete dam against the assumed uplift pressures used in the stability analysis. This would confirm that the dam stability is (or is not) meeting the accepted factors of safety envisaged by the designer.

Regular review of the monitoring data by a dam safety engineer familiar with the dam is essential, and can be aided by alerts and alarms. Setting alert and alarm levels needs to consider both design expectations and historical precedent for the instrument. When an alert or alarm is triggered, automated messages should be sent to the dam safety team for review and interpretation.

In summary …

As we’ve discussed here, making the most of dam safety monitoring requires a carefully considered and comprehensive process, in which:

• instruments are targeted to detect key failure modes
• instruments are carefully installed and the process is well documented
• data produced by the instruments is checked and validated
• data is securely stored as a permanent record of the dam performance
• data is regularly reviewed and interpreted by experienced dams engineers.

Technology alone doesn’t keep dams safe, but when paired with sound engineering judgement, effective dam safety monitoring provides a strong foundation for safer, more resilient and more sustainable dams that can serve communities for generations.

ABOUT THE AUTHOR

Paul Southcott (Senior Principal – Dams and Headworks) is Convenor of ANCOLD’s ‘Guidelines for Dam Instrumentation and Monitoring Systems Working Group’. He has nearly four decades of experience in civil and dam engineering, with an exceptional depth of technical knowledge and extensive industry experience. Paul’s expertise is a crucial part of Entura’s ongoing support for dam upgrade and safety works for our clients’ extensive dam portfolios. He has contributed to many major dam and hydropower projects throughout Australia and the Indo-Pacific region, including for Hydro Tasmania, TasWater, Snowy Hydro and numerous councils and water utilities including SeqWater, Sun Water and SAWater. Paul was named Tasmania’s Professional Engineer of the Year in Engineers Australia’s 2021 Engineering Excellence Awards.

Three principles for planning better dams

Dams are critical infrastructure in a world shaped by climate uncertainty, growing populations and rising pressure on water, food and energy systems. Storage is central to water security, climate resilience and the renewable energy transition. But the focus cannot simply be on building more infrastructure. The challenge is to identify and develop the right dams in the right places, with the right planning to manage impacts and produce long-lasting value.

This theme resonated strongly at the recent ICOLD conference in Guadalajara, Mexico. Throughout discussions on water planning, environmental impacts and sustainability, one point stood out: the quality of a dam project is largely shaped long before detailed design gets underway. By the time a project is technically mature (i.e. the arrangement has been fixed), some of the most important opportunities to improve outcomes have already passed.

In practice, 3 planning principles matter most.

1. Start with the river basin, not the individual project

The best dam planning begins at basin scale. Before comparing individual sites or refining layouts, it is essential to understand the wider river system, competing water demands, environmental constraints and social context. A Strategic Environmental Assessment (SEA) helps provide that broader view by evaluating environmental, social and economic effects early in the planning process, when there is still flexibility to shape decisions.

This matters because some parts of a basin are more suitable for development than others. Some areas carry high environmental or social value and should be avoided. Others may present lower overall risk and therefore provide a more sustainable pathway for development. Basin-scale planning helps identify this early. It also supports better application of the hierarchy for mitigating impacts – from most to least preferred: avoid (best!), minimise, rectify, reduce, offset (only as a last resort).

For project proponents, this kind of early strategic assessment can increase sustainability while also reducing conflict, supporting more robust approvals pathways and giving decision-makers greater confidence that the project is in the right place.

2. Choose projects using a broad decision lens

Once lower-risk opportunities have been identified, the challenge becomes deciding which project should move forward. This decision shouldn’t be based on economics alone. The most successful projects are usually those selected through a structured multicriteria assessment that considers technical feasibility, financial performance, environmental risk, social impact, safety and long-term resilience together.

A funnel provides a useful analogy. There may be many possible project options at first. Through an iterative process of evaluation and comparison, the range narrows until only the strongest candidate remains. The value of this process depends on whether the criteria reflect the full picture of project success.

The Hydropower Sustainability Alliance’s HydroSelect tool supports this kind of early-stage thinking. It considers 12 sustainability factors such as societal contribution, water quality, sedimentation, dam safety, downstream flows, biodiversity, cultural heritage, resettlement and livelihood impacts, and climate change. Although developed for hydropower, the tool is relevant to all dams: the best project is not necessarily the cheapest or fastest to develop; it’s the one that stands up best when all risks and benefits are weighed up.

This kind of screening is particularly valuable for identifying red flags before they become too difficult to resolve.

3. Recognise that impact is greatest in the early phases

The planning and concept stages have the greatest influence on a project’s long-term outcomes. This is when decisions about site selection, dam type, reservoir level, spillway configuration, operational rules and mitigation measures are still open to improvement. Once the project moves into later phases, changes become more constrained and often more costly to implement.

Multidisciplinary planning is very important for better outcomes. Engineers should work alongside environmental scientists, ecologists, social specialists, geologists, sediment experts, hydrologists and dam safety practitioners from the conceptual stages of the overall general arrangement. A collaborative approach allows potential impacts to be identified early and addressed right from the start.

The benefits of multidisciplinary planning can flow into successful multipurpose projects, where a dam can deliver even greater value beyond its primary purpose. A better understanding of habitat and land use in the reservoir as well as downstream will enable better decisions about final reservoir level, operating regimes and spillway arrangements to manage floods safety. Early knowledge of sediment behaviour and downstream needs will shape flushing provisions and operational rules. Better understanding of environmental flow requirements and fish migration will improve outlet works and the design of successful fish passages. The earlier and broader the understanding, the better the ultimate decisions.

Dam safety must, of course, be prioritised at this stage. Decisions about dam type should be based on a deep understanding of the hazards the dam may be exposed to during its life and by considering all the potential failure mechanisms and the societal risks. While appropriate surveillance (both visual inspections and instrumentation monitoring) remains essential throughout operations, the foundations of a safe dam are laid during planning and concept development.

Better planning yields better outcomes

Large dams can be controversial, particularly when their environmental and social impacts have not been well understood or well managed. This is why good planning matters so much. If we start with basin-scale thinking, compare options using a broad range of criteria, and make the most of the early project phases with multidisciplinary expertise, we have a far better chance of delivering infrastructure that is safe, defensible and genuinely valuable over the long term. It’s a pathway to achieving the right dams, in the right places, with the right outcomes.

ABOUT THE AUTHOR

Richard Herweynen is Entura’s Technical Director, Water. He has more than 3 decades of experience in dam and hydropower engineering, working throughout the Indo-Pacific region on both dam and hydropower projects. His experience covers all aspects including investigations, feasibility studies, detailed design, construction liaison, operation and maintenance, and risk assessment for both new and existing projects. Richard has been part of a number of expert review panels for major water projects. He participated in the ANCOLD working group for concrete gravity dams and was the Chairman of the ICOLD technical committee on engineering activities in the planning process for water resources projects. Richard has won many engineering excellence and innovation awards (including Engineers Australia’s Professional Engineer of the Year 2012 – Tasmanian Division), and has published more than 30 technical papers on dam engineering.

Making defensible dam engineering decisions in an ever-changing world

New technology, evolving climate science, aging infrastructure and workforce turnover are reshaping what it takes to design, assess and manage dams responsibly.

In this article, two of Entura’s dam professionals outline key considerations that today’s dam engineers should keep firmly in mind when making dam engineering decisions.

1 Keeping pace with changing technology for dam engineering and monitoring

Dam engineers now have access to far greater computing power and analytics than ever before, which means we can estimate extreme flood behaviour, seismic loads and complex structural responses in unprecedented detail.

But, as the saying goes, with great power comes great responsibility. Highly sophisticated models can create a false sense of certainty, but models are only as good as their inputs and assumptions. It’s up to us as dams engineers to use sound engineering judgement to interrogate model reliability, to identify uncertainty and to understand the limitations of the modelling in decision-making.

Advances in monitoring and surveillance have been equally rapid and sophisticated, with remote sensing and automated, near-real-time data acquisition allowing earlier and more precise detection of potential issues. The challenge, though, is managing an immense flow of data to filter and interpret.

Artificial intelligence (AI) could be a game changer for efficiently collating and interpreting data, helping detect trends and anomalies. However, using AI as a decision-making tool has limitations and its outputs could be misleading. There’s also a risk that overreliance on AI could erode our opportunity to independently exercise and apply professional engineering judgement.

Against a backdrop of advancing technology, dam engineers must still bring a holistic understanding of a dam’s underlying design philosophy, the performance of structures under various load conditions, and the impacts of construction practices on dam behaviour.

2 Deepening the understanding of failure modes and risks

Risk-based dam safety practices are now firmly embedded in Australian and international dam safety guidance. Failure modes analysis and risk assessment form the foundation of prioritised risk-based dam safety surveillance programs and dam design.

Assessing failure modes demands a multidisciplinary perspective and collaboration. Geological and foundation conditions, climate conditions and the implications of construction sequences and historical modification could result in vulnerabilities that are not apparent in routine inspections.

Tools such as LifeSim and TotalRisk quantify social, economic and environmental risks – which can help inform, justify and clearly communicate decision-making about the timing and scope of risk mitigation works.

3 Considering the impacts of climate change

For dam engineers, consideration of environmental factors is nothing new. However, the potential for significant changes in climate, and the consequences of these changes and associated uncertainty, are increasingly important and complex concerns.  

Updated climate projections and hydrological guidance, including the most recent update to Australian Rainfall and Runoff (Ball et al. 2019), have altered design flood estimates in many regions. In some cases, this has reduced flood capacity margins and prompted reassessment of spillway adequacy and flood tolerability for both near-term and long-term climate scenarios.

In addition to increased rainfall expectations, we also need to consider the impacts on dams during prolonged periods of low rainfall, such as drying and cracking of the clay core material in embankment dams.

Today’s dam engineers need to consider a wider range of plausible future scenarios and engage explicitly with uncertainty across the asset’s remaining life.

4 Working towards sustainability

Sustainability is an increasing focus for dam owners and regulators. Dam upgrade and remediation projects need to consider expectations around reducing carbon emissions, lowering the environmental footprint, and improving the process and outcomes for local communities.

For dam engineers, this means thinking beyond traditional approaches and being prepared to challenge long-held assumptions. Can the construction and carbon footprint be reduced? Can existing materials be reused onsite to reduce haulage and waste? Are there options to improve safety outcomes? How can works be designed to improve, rather than degrade, local biodiversity or downstream environments?

To answer these questions, we need to engage as early as possible with industry best practices, and collaborate with environmental specialists, experts in carbon accounting, peak standards bodies and stakeholders. We should also learn from projects that are demonstrating innovation and successful outcomes.

5 Navigating competing priorities

Scrutiny by the community, stakeholders and dam safety regulators with respect to the safety and sustainability of dams and upgrade works continues to increase, but at the same time many dam owners face constrained budgets and competing priorities across their infrastructure portfolio, which may mean staging dam upgrades.

Many large dams are now more than 50 years old and may be inadequately monitored or in need of remediation works. However, the limited budgets of public and private sector dam owners can constrain their ability to fund comprehensive surveillance programs and dam safety remediation works.

Dam engineers, therefore, have a complex advisory role. Our recommendations need to be risk‑informed, prioritised, staged where appropriate, and defensible in technical, economic and societal terms. Clear communication of residual risk, uncertainty and long‑term implications is critical.

As in any infrastructure project, meaningful engagement with communities and stakeholders can improve the process and the outcomes. Explaining clearly why certain works are prioritised, how risks are being managed, and what communities can expect during upgrade construction grows trust and can help defuse conflict. This may not sound like the role of the engineer but it is our inputs, translated into plain language, that will help create accessible, honest narratives that help stakeholders and communities understand what’s happening and why.

6 Futureproofing the workforce

Ultimately, safe and sustainable dams depend as much on skilled and experienced people as on technology. But a global skills gap is emerging as experienced dam engineers retire, taking with them invaluable institutional knowledge of older assets, construction practices and surveillance practices and priorities. This is certainly the case in Australia, given that new dam construction has declined steeply over the last few decades, reducing opportunities for first-hand experience.

Preserving design knowledge, construction understanding and institutional memory is important, and it won’t happen by accident. Investing in mentoring and knowledge transfer will be key to ensuring that younger and emerging dam engineers learn as much as possible from experienced senior engineers before they retire. Tailored training from experienced engineers and providers can also help bridge context gaps. Where local experience is limited, there may be opportunities to draw on international expertise or related industries.

We encourage all dams engineers to get involved in industry initiatives led by organisations such as ANCOLD and Engineers Australia, including emerging professional networks and mentoring programs, so that together we can grow capability across our sector.

ABOUT THE AUTHORS

Jaretha Lombaard joined Entura as a Senior Dams Engineer in January 2024. She has a range of experience in dam and water resource engineering in Southern Africa and Australia. She is experienced in numerous aspects of dam engineering, including dam design, tender and construction support, dam safety assessments and inspections. She has also been involved in developing dam safety emergency management plans, operations and maintenance manuals, and is actively involved in facilitating dam safety training through the Entura Clean Energy and Water Institute (ECEWI). Jaretha has taken lead roles on various projects, including as the design manager for the Bradys Dam upgrade and Meadowbank Dam upgrade projects.

Sally Fracalossi is also a Senior Dams Engineer. She joined Entura’s Dams and Geotech team in 2020, following 5 years in a multinational private consultancy where she gained a broad civil engineering and project management experience. Sally is experienced in numerous aspects of dam engineering, including dam design, dam safety assessments and inspections, risk assessment and construction support. She has also been involved in developing dam safety emergency management plans, operations and maintenance manuals, and is actively involved in facilitating dam safety training through the Entura Clean Energy and Water Institute (ECEWI). Sally was project manager for TasWater’s dam safety surveillance program which encompassed over 50 referable dams in the north and south of the state during 2020–22.

What do dams and bathtubs have in common?

The obvious answer is that both hold water, but there’s something more, which keynote speaker Andrew Watson of BC Hydro referred to at the recent NZSOLD/ANCOLD conference. He described the risk profile of a dam over time as ‘the bathtub curve’.

The riskiest periods for a dam are during the early years of operation and in later years as the dam starts to age.

We talk a lot about managing the risks of older dams through an appropriate dam safety program. A dam portfolio risk assessment is a great way of ensuring effort is focused appropriately. If the risk profile of an aging dam reaches an unacceptable level, this can result in a dam upgrade project. Clearly, there are many well-established processes and tools to manage risks on the aging dam side of the bathtub curve, but how about for new dams?

Reducing risk during design

During the design phase of a dam, we investigate the foundations, develop geological models to represent the foundation and assign geotechnical properties to the elements in our model. We also investigate materials that will be used in the dam, undertake laboratory testing to achieve material properties, and may even undertake insitu trials. We then model the dam structure to determine how it performs for various load cases, including extreme flood and earthquake loading, ensuring it meets the required engineering standards. Although the design process has checks and balances, some uncertainties and risks may have escaped identification at this stage.

Reducing risk during construction

The next phase is constructing the dam in accordance with the design specifications. A quality control assurance program sets quality control measures to give confidence that the construction meets the design requirements. Although the quality assurance and quality control systems are in place, there is still a level of uncertainty, making it difficult to guarantee that all the materials placed meet the required specification. Additionally, the foundation and material conditions may not totally reflect the design characterisation, necessitating modifications during construction. Typically, the designer is engaged in these changes, but was sufficient supervisory expertise on site to recognise these differences and engage the designer?

Reducing risk during first filling

For a dam design engineer, the filling of a new dam is often an exciting time. It is the completion of a major project, but it is also known to be the highest risk stage of a dam’s life. Everything that has gone into the design and construction of the dam is going to be tested for the first time: the design assumptions and models, the actual material properties, the engineering calculations, the quality of construction, the quality assurance systems, etc.

How can risk be mitigated during this first filling and the early years of operation, when the dam is being tested? From our experience, these practical steps can help reduce the risk (click each step for more details):

This process for new dams should apply equally to main dams and smaller saddle dams. In larger reservoirs, water may not fill against a saddle dam for a year or two after the commencement of impoundment. In this case, the same principles should be applied to the saddle dam during the period when water is against it for the first time. These principles also apply when a dam is raised, because when water load is placed against the raised section, the raised dam is being tested for the first time.

By applying these steps through the heightened risk period during first filling and the first 5 years of operation, dam professionals can mitigate the risks associated with the early side of the bathtub curve, helping the dam get a good start in life.

ABOUT THE AUTHOR

Richard Herweynen is Entura’s Technical Director, Water. He has more than 3 decades of experience in dam and hydropower engineering, working throughout the Indo-Pacific region on both dam and hydropower projects. His experience covers all aspects including investigations, feasibility studies, detailed design, construction liaison, operation and maintenance, and risk assessment for both new and existing projects. Richard has been part of a number of expert review panels for major water projects. He participated in the ANCOLD working group for concrete gravity dams and was the Chairman of the ICOLD technical committee on engineering activities in the planning process for water resources projects. Richard has won many engineering excellence and innovation awards (including Engineers Australia’s Professional Engineer of the Year 2012 – Tasmanian Division), and has published more than 30 technical papers on dam engineering.

Poutès Dam – a model of sustainable dam redevelopment

Having been named as the Planning Institute of Australia’s Young Planner of the Year for 2023 and awarded a bursary, Entura’s Bunfu Yu travelled through Switzerland and France to study hydropower and energy innovation. Her tour to Poutès Dam in France made a powerful impression. Here she reflects on what Poutès Dam demonstrates about environmentally driven engineering design and how genuine engagement with stakeholders in a design process can lead to balanced outcomes …

The Poutès Dam, located on the upper Allier River, a tributary of the Loire River in central France, has become a landmark case study of how to reconcile renewable energy production with environmental restoration. It’s a project that benefitted from genuine engagement, environmental-led engineering design principles, and future-conscious leadership by its operator, Electricité de France (EDF).

The dam was built during World War II without the usual approval processes. It has long been an obstacle to migratory fish, such as Atlantic salmon from the Allier basin, blocking the return of spawners and the downstream migration of juveniles. It has also disrupted the natural sediment flow of the Allier.

From conflict to collaboration

In the 1980s, environmental organisations highlighted the impact of the dam as a cause of the drastic decline in the wild Atlantic salmon population in the Loire-Allier basin. A sustained mobilisation of environmental groups through the 1990s evolved into a lengthy anti-dam campaign. In the mid-2000s, when EDF applied to renew its operating concession, it attracted criticism and rejection from global environmental NGOs, including WWF.

After decades of debate involving local communities, environmental NGOs, the dam operator (EDF Hydro) and public authorities, a compromise was reached in the late 2000s by which the parties agreed on a commitment to sustainable hydropower. Rather than completely remove the dam, a large-scale reconfiguration project – dubbed the ‘New Poutès’ – was born.

In 2015, EDF achieved a 50-year renewal of its licence, conditional on stringent environmental performance requirements, particularly regarding fish migration and sediment transport. It marked a new life for the project: those who once stood on the site of the dam in protest were now collaboratively discussing the future of Poutès with the operator and public authorities.

The ‘New Poutès’ project

A substantial refurbishment of the dam was carried out over several years to 2021, with the renovated dam inaugurated in October 2022. The design carefully configured to improve salmon migration and achieve the desired environmental outcomes.

• The dam height was lowered from 18 m to 7 m to reduce the water head and the reservoir’s impact. The embankment is also shaped in such a way that, along with the reduced hydraulic drop, the fish have a shorter and smoother vertical barrier to overcome.
• The reservoir length was decreased from 3.5 km to under 500 m, restoring much of the river’s natural profile (including a natural river gradient that allows salmon to swim) and rebuilding downstream spawning habitat.
• Two large centrally located sluice gates were installed, which can be fully opened during fish migration seasons and for high-flow water releases, allowing sediments and aquatic fauna to circulate freely. This is considered the key innovation to rejuvenate the river’s ecological dynamics.
• Fish-pass structures (fishway and fish elevator) have been incorporated in the design, which operate every 2 minutes to ensure upstream and downstream migration is effective.
• While the turbine flow remains similar to before, generation is paused during key periods to prioritise fauna movement.

The fish ladder in action

Ecological and social benefits match technical success

The New Poutès redevelopment did more than update an old hydropower plant; it reconnected a fractured ecosystem, restoring sediment flow and providing effective fish migration routes. The New Poutès continues to supply about 85% of its original hydroelectric output.

Importantly, this project demonstrates the potential of ‘collective intelligence’; that is, collaboration among diverse stakeholders (government, operator, NGOs, local communities) to produce outcomes that are superior to those achieved through conflict or unilateral decisions.

Moreover, it challenges the notion that dams are immutable – a rigid infrastructure at odds with the environment. Instead, New Poutès embodies a modern, adaptive approach: engineering solutions that evolve over time, responding to environmental and social imperatives.

Lessons from Poutès

As many dam owners and operators consider the future of their aging dams and the need for sustainable management, New Poutès stands out as a model. It shows that:

• with thoughtful design and management, hydropower and biodiversity can coexist
• partial removal and targeted retrofitting of a dam can sometimes be a cost-effective and ecologically positive alternative to full demolition
• restored rivers can recover ecological functions like fish migration, sediment transport and dynamic flow regimes, contributing to broader goals of ecological resilience
• multi-stakeholder participatory processes combining NGOs, operators, authorities and communities can help reconcile competing interests and produce durable solutions.

For me, as a planning specialist, this last point resonated particularly powerfully. It’s exciting to see a project that has learned from the lessons of the past, engaged openly and genuinely with its community, and navigated a path toward greater long-term sustainability.

When environmental, social and heritage values are considered from the outset and integrated into dam design, upgrades and refurbishments, the outcomes are better for everyone. In the Poutès story, it took the loss of the operating licence to make a major leap. Proactive efforts to bring a better balance to the ledger of impacts verse benefits may help avoid such dramatic circumstances.

Having finished my study trip and returned to Tasmania, I’m excited to continue my involvement in Entura’s projects involving dam refurbishment, redevelopment and upgrades – including the new lease on life being planned for Hydro Tasmania’s Tarraleah hydropower station. This project is sure to find itself amongst global examples of leading practice, setting the standard for other owners of older hydropower assets.

Bunfu thanks EDF team members Benoit Houdant (Technical Director Engineering) and Sylvain Lecuna (project manager of the Poutes Dam project), and Roberto Epple (former President of the European Rivers Network) for the site tour. It was incredible to share a site tour with representatives of 2 parties that were once in opposition, but now share in the pride of Poutès.

Poutès Dam and surrounding topography

Close-up of Poutès Dam

ABOUT THE AUTHOR

Bunfu Yu is a dynamic young leader in renewable energy planning, approvals and business development. Bunfu was named the National Young Planner of the Year by the Planning Institute of Australia. This honour recognised not only her passion for planning and delivering renewable infrastructure but also her active contribution to the profession through mentoring, public engagement and knowledge sharing. She is currently a Senior Environmental Planner and a Business Development Manager at Entura.

Dam decommissioning: old dams, new opportunities

While many dams have very long lives, and could in theory operate for centuries, some dams reach a point at which decommissioning becomes a realistic final phase of the dam life cycle.

Decommissioning is not something that happens very often, given the significant value of dams and their functions, which are often multiple. Maintaining and upgrading dams, rather than decommissioning, can sometimes also be a more sustainable solution if this extracts more economic, social and environmental value to offset the initial impacts that the dam may have caused when originally constructed.

However, decommissioning may be the best option if the dam is no longer needed to deliver its original purpose, if it is no longer providing commercial or societal benefits, or if it is considered too costly to continue maintaining the dam or to undertake the necessary upgrades to stay compliant with contemporary regulations and standards.

How is a decision to decommission made?

The decision to decommission a dam is usually based on a comprehensive risk assessment. Risk assessments play a critical role in managing dams throughout their life cycle. They primarily focus on ensuring safety and minimising risks associated with dam operation, failure and decommissioning.

Risk assessments estimate risks, identify hazards and failure modes, evaluate the tolerability of the risk, compare potential risk reduction measures if needed, and establish a risk reduction strategy.

If the risk is not tolerable, risk reduction measures will be recommended, and a risk reduction strategy will be established to reduce the risk. The risk reduction measures will generally involve upgrade works. When the option to undertake dam upgrade works is considered, the option to decommission the dam is often also included. The dam owner can then undertake a cost–benefit analysis to determine the most viable option, understand the level of risk reduction achieved, and consider less tangible aspects such as community concerns.

What’s involved in decommissioning a dam?

Decommissioning a dam requires considerable planning to minimise environmental impacts and reduce the chance of leaving any residual hazards in the long term. A thorough assessment of the site conditions and downstream environment is a crucial first step towards identifying the appropriate decommissioning actions.

The location of the dam and the details of the dam works will determine the planning requirements, which often include:

• engineering design – taking breach width and batters into account to remove the possibility of retaining water, and assessing the impact on flooding downstream (as dams frequently provide flood mitigation even when this is not their primary function)
• sediment and erosion control planning – as sediment release can cause significant water quality issues and harm to habitats downstream. It is important to note that the reservoir area will initially be unvegetated and will not have any topsoil that can be used to support vegetation growth to control erosion. Additionally, sediments will typically have been deposited in the dam reservoir and are generally very easily remobilised, so this needs special attention from the designers
• flora, fauna and cultural heritage studies – as decommissioning can dramatically alter ecosystems both upstream and downstream, and heritage features can often be highlighted improving the amenity of the new asset. Ecological studies such as flora and fauna assessments are important to identify any threatened species that need to be considered in the decommissioning plans, such as through exclusion zones or timing the works to minimise impacts (e.g. conducting work outside of breeding seasons)
• fluvial geomorphology assessment – which identifies how rivers interact with their landscapes and how they change over time. It is important to understand this given that the decommissioned dam will have water flowing through it rather than retaining water, changing the balance of erosion and sedimentation processes
• dam safety emergency plan for decommissioning works – to protect communities from flooding during the decommissioning works
• regulatory approvals – a dam decommissioning permit will be needed, which will include managing any specific regulatory requirements such as issuing a notice of intent prior to commencing works and providing work-as-executed reports and drawings at the completion of the works to confirm all conditions have been successfully met.
• Depending on the use and location of the dam, it is recommended to consult with a range of stakeholders, including the local community and council, during the planning process to ensure that their perspectives and concerns are considered early. If the dam is located near to residences, public spaces or other civic amenities, extensive consultation is likely to be needed due to the potential nuisance from the works (e.g. noise, dust and additional traffic in the local area). A masterplan can be developed through this process of consultation, outlining potential options for remediating and repurposing the area based on the community’s priorities, such as creating potential new community assets such as wetlands, parks or sporting facilities.

The work involved in decommissioning a dam will depend on the type of dam and the surrounding environment but commonly involves:

• re-routing inflow away from the reservoir or past the dam
• removing all or part of the dam wall
• modifying or removing the outlet works
• lowering the spillway crest level or removing the spillway control gates or stop-boards
• treating retained liquid prior to discharging it in a safe condition
• stockpiling and stabilising accumulated sediments from within the reservoir
• removing or encapsulating impounded material, such as trees and vegetation
• revegetating the reservoir area and rehabilitating the site to perform its new purpose.

Doing it safely

Decommissioning a dam is a very complex matter involving many stakeholders and often taking some time to reach its conclusion, so it is prudent for dam owners to embark early on some interim measures to rapidly reduce any identified dam safety risks. The simplest and most cost-effective risk reduction measure is usually to lower the level of the reservoir.

The next stage is identifying the planning requirements and works involved with decommissioning and developing a decommissioning plan. The engineering design, included in the decommissioning plan, will consider the necessary environmental assessments and ensure adherence to appropriate guidelines.

Common considerations when developing the engineering design include:

• hydrological and hydraulic assessment of conditions before and after decommissioning
• the necessary breach width and batters to make the site safe
• safely discharging or removing retained water and material
• the volume of any attenuated water remaining after decommissioning
• gradient of the land if the reservoir is being completely drained
• erosion and sediment control during and after decommissioning
• managing inflows and floods during the decommissioning
• careful consideration of the final land use after decommissioning including the ecological restoration and community uses.

Achieving success

For decommissioning to be considered successful, it’s crucial that the decommissioning plan and engineering design take account of the priorities that emerge from stakeholder consultation. Many communities become attached to a dam as part of their local landscape, especially if the dam is very old. They may wish for some of the dam’s heritage to be retained or acknowledged in some way, such as retaining and integrating parts of the abutment into the future form or land use where it is safe to do so, or echoing the past by incorporating smaller water features into the resulting site.

Another major consideration for successful decommissioning is controlling erosion and sediment. Reservoirs typically have a low point that can function as a temporary sediment basin once the water level is substantially lowered. Rainfall and inflows can be channelled with small bunds and hessian silt rolls to the sediment basin. Turbid water can then settle or be treated, if necessary, before being pumped out. After decommissioning, erosion and sediment can be managed by revegetating exposed areas with native plants, creating habitat features such as wetlands or log jams, and managing and monitoring wildlife to ensure their adaptation to the changing environment. Simple solutions can be implemented to achieve positive – or at least neutral – outcomes for biodiversity.

Right process, right people

Decommissioning dams takes a wide range of skills to deliver a successful outcome – from hydrology and hydraulics, environmental and heritage assessments, through to detailed construction planning and a vision for the repurposed land. With the right people and process, decommissioning can reduce safety risks to the community, protect the environment during the works, and ultimately create new, sustainable assets enhancing the amenity of the area for the benefit of communities now and long into the future.

Entura has been involved in a number of dam decommissioning projects including Waratah Dam and Tolosa Dam. To talk with Entura’s specialists about a dam decommissioning project, contact Richard Herweynen or Phillip Ellerton.

ABOUT THE AUTHOR

Joey Scicluna is a civil engineer, who began his career managing commercial and subdivision projects. Since joining Entura’s dams and geotechnical team in 2022, he has undertaken a wide range of dam safety surveillance inspections and reporting, dam safety modelling and analysis and risk assessments. Joey has been the lead author for a number of intermediate and comprehensive dam safety reviews, and has developed design concepts and conducted feasibility studies for existing and new dams projects. Joey enjoys problem solving and working with stakeholders to achieve the best outcome for every project.

Risk is the word – reflections on the NZSOLD/ANCOLD 2025 conference

From 19 to 21 November 2025, industry experts from consultants to asset owners gathered in Ōtautahi Christchurch, New Zealand, to exchange insights, challenge thinking and strengthen connections ‘across the ditch’ and beyond. Here Entura’s Sammy Gibbs reflects on the conference …

If I had dollar for every time I heard the word ‘risk’ across the two-day event, I might have been able to fund next year’s conference myself!

Why was this the case? As noted in many of the presentations and papers, the dam industry is facing the combined challenges of aging dam infrastructure, changing design standards, climate change impacts, community expectations and resource/cost constraints. As a result, the industry is shifting more towards risk-informed decision-making/frameworks, compared to traditional standards-based approaches,to manage and design dam infrastructure.

No dam is 100% safe and all risks can never be designed out entirely, but a sophisticated understanding of their risk can inform our decisions and actions so that we can target key issues cost-effectively and ensure resilience in our dams and water infrastructure.

Risks in asset ownership

In his opening address, Andrew Watson, Director of Dam Safety & Generation Asset Planning at BC Hydro in Canada, provided valuable insights into how BC Hydro uses a risk-informed framework to manage its dams. He discussed the use of a ‘vulnerability index’ to understand the significance of identified physical deficiencies in the dam portfolio. The higher the index, the greater the likelihood that the deficiency would result in poor performance. This index allows BC Hydro’s dam safety team to understand the overall risk profile and prioritise future works. It left us contemplating how the ANCOLD 2022 Risk Assessment Guidelines and ALARP process may be enhanced by integrating components of this approach. This could be a useful way of measuring how far the dam is from meeting ‘best practice’ and hence enhance the justification for further risk reduction or accepting the position as ALARP.  

Later in the conference, Andrew Watson was joined by Peter Mulvihill, Lelio Mejia and Barton Maher to discuss legacy risk and how to manage it. Legacy risk is relevant for many asset owners (nationally and internationally) as our sector faces the complexities of inheriting aging facilities, acquired from past organisations/owners. A key challenge with these legacy structures is the transfer of knowledge to new asset owners. Important records such as monitoring data, design and construction information are often lost (or were never developed), making it difficult to understand and quantify the current risk position of the structure. These aging facilities are also unlikely to meet current design standards or withstand climate change impacts. Risk-informed decision making and phased approaches become critical in such instances, as does asking the question ‘Does it matter?’ when it comes to unknowns. Like tying surveillance programs to key failure modes, unknowns should also be associated with credible failure modes.

It was noted that for some of these structures the most appropriate solution is decommissioning, as the risk imposed by the structure (and the cost to mitigate it) may outweigh the economic benefit of the asset itself. In such instances, this decision can provide social and environmental benefits and are worth investigating.

Risk in surveillance monitoring

The conference reaffirmed the critical role of risk-based surveillance monitoring and the importance of understanding how dam instrumentation relates to key failure modes and/or performance. The most effective tool to support this is an event decision tree.

Entura’s Diego Real reiterated the importance of understanding key failure modes when implementing instrumentation upgrades. His paper presented a staged approach for the upgrades, providing clients with a cost-effective, practical solution that assists in managing dam safety risks.

Although there was discussion about various ways in which surveillance programs can be optimised, our industry is aligned in recognising the criticality of undertaking routine inspections as the first line of defence when it comes to identifying potential failure indicators.

Risk mitigation solutions

Several presenters shared examples of bespoke solutions responding to dam risks – including Entura’s Jaretha Lombaard, who highlighted how a Swedish berm was used to mitigate risks associated with piping failures at an earth and rockfill embankment dam in Tasmania.

Other risk mitigation solutions presented included non-physical works such as improvements in surveillance and monitoring. In one example, alarm systems in rivers are being used effectively to warn and evacuate the public in a swimming pool downstream in the event of a flood. Instead of relying solely on costly capital-intensive physical upgrades, the most effective strategy for reducing societal risks may lie in enhancing the speed and reliability of early warning systems.

Sharing knowledge to tackle similar problems

NZSOLD/ANCOLD 2025 was an excellent opportunity to see how specialists are tackling the complex challenges facing the dams industry. Walking away, my mind was full of phrases involving the word ‘risk’, but I felt reassured that we are all facing similar problems and by sharing our knowledge and innovations we’re continually improving our ability to design, monitor and maintain dams.

This conference will be a tough act to follow, but I look forward to the 2026 ANCOLD conference to be held in Lutruwita/ Tasmania (where I live and Entura originated).

ABOUT THE AUTHOR

Sammy Gibbs is a civil engineer with 7 years of consulting experience and joined Entura’s Dams and Geotech Team in May 2021. Sammy has a diverse background in dam and water engineering and works on a range of projects including consequence category assessments, hydrology studies, hydraulic design, risk assessments and dam design projects.

Reflections from MYCOLD 2025: Innovation, resilient dams and the evolving role of hydropower

Earlier this month, I had the privilege of joining colleagues from across Malaysia and the region at the 3^rd International Conference on Dam Safety Management and Engineering (ICDSME2025), organised by the Malaysia Commission on Large Dams (MYCOLD), held in Kuching, Sarawak. There’s a particular energy that comes with a MYCOLD conference – part reunion, part technical deep-dive, part regional conversation about water, resilience and community safety.

I returned energised and inspired – not only by the technical excellence on display, but also by the sense of shared purpose across our industry and the tangible people-to-people exchanges and collaborations. With energy systems transforming rapidly, climate change accelerating and dam safety expectations strengthening, it has never been more important for dam and hydropower professionals to share openly and learn from one another. ICDSME2025 offered that in abundance.

Here are just a few reflections on some of what I heard …

Reimagining hydropower in changing markets and climates

In the ‘Advancing sustainable hydropower’ session, I shared perspectives from Tasmania’s long hydropower journey and Entura’s experience supporting the state’s major renewable energy initiatives.

My message was clear: the feasibility of pumped hydro or of reimagining conventional hydropower isn’t simply a technical question of ‘can we build it?’ but ‘what is the long-term value it creates?’ Smart choices depend on a holistic understanding of context – i.e. the markets, energy mix, climate, environmental impacts and benefits, and community perspectives and impacts. Pumped hydro is never ‘impact-free’, and it is not inherently more sustainable than conventional hydropower. What matters is how we think about the future of the energy transition, understanding what role pumped hydro can play in that context, how well we select sites, how carefully we consider environmental and social impacts, and how thoughtfully we design (and extend) assets for long-term economic and social value.

With wind and solar dominating new energy investment in Australia, hydropower’s baseload role can shift to respond to evolving market dynamics. Hydropower’s deep storage, flexibility and system stability are becoming increasingly important. We’re seeing these opportunities in Tasmania, where both conventional hydropower and pumped hydro could – with more interconnection to the mainland – help balance a renewables-rich National Electricity Market while returning extra revenue to Tasmania and increasing the reliability of supply across Australia’s south-east.

Climate change adds further complexity to feasibility considerations. Changing rainfall patterns, more variable inflows and more frequent extremes – as well as with the increasingly variable generation mix and how energy sources interact – all influence when hydropower can generate or store.

Ultimately, I believe there are not only opportunities with extending operating life, refurbishing or redeveloping dam assets; there are also obligations upon us as an industry to do our best for the sustainability of these assets. We need to focus constantly on how to optimise outcomes from the base impacts of hydropower or dam developments and seek ways to reduce impacts into the future. We also need to think about how to deliver great outcomes and value that extends across a long asset life, beyond the limited commercial timeframes considered in final investment decisions.

Technology, people and the future of dam safety

I had the honour of chairing a keynote session featuring Yang Berbahagia Prof. Datin Ir. Dr. Lariyah binti Mohd Sidek and Dr Martin Wieland.

Dr Wieland’s insights into the seismic performance of dams reminded us that strong engineering fundamentals remain as crucial as ever, even as digital tools advance. Prof. Lariyah explored how digital platforms, artificial intelligence and risk-based frameworks are shaping the next generation of dam safety practice. She emphasised the importance of the human layer: building institutional readiness, strengthening safety culture, fostering stakeholder trust, and ensuring effective engagement with communities.

Together, their perspectives reinforced that the future of dam safety will depend on both technological innovation and human-centred capability and how effectively these dimensions interact. That’s something Entura is focused on as we continue to bring deep expertise and experience, while exploring and testing the possibilities of new technology to support design and analysis.

Learning from incidents to strengthen global knowledge

Another highlight for me was chairing a session on dam surveillance, monitoring and evaluation. Seven presentations, while different in context and purpose, in combination emphasised the power of data and the importance of learning from experience.

A standout paper examined the 2022 landslide incident at Kenyir Dam, an event that occurred quite soon after Entura’s dam safety inspector training program used the dam as a site visit capstone. Despite extreme rainfall and slope instability, and some damage to appurtenant structures and spillway, instrumentation data confirmed that the dam behaved as designed. What was also clear was that, largely, the instrumentation in place and the data that was able to be collected was a positive demonstration of the importance of robust dam design and monitoring systems.

Another paper explored machine-learning approaches to forecasting short-term reservoir levels at Batang Ai Hydroelectric Project – a scheme with which Entura has long been associated. The results were impressive and point to a future where AI-supported forecasting strengthens real-time operations, especially under increasing climate variability.

These are exactly the kinds of insights our industry must continue to share openly and widely. We can never ‘design out’ all risk, but we can reduce it through good data and continual reflection and learning from real-world events.

Strengthening long-term capability in Malaysia

ICDSME2025 also highlighted the importance of building capability – something I am passionate about. It was encouraging to see Malaysia’s Certified Dam Safety Inspector program, developed with input from Entura’s training arm ECEWI, growing into a sustained and locally led pathway, launched during the conference. Strengthening dam safety ultimately depends on skilled people and strong institutions, making investment in training an investment in long-term sustainability of dam safety governance – and ultimately greater national resilience. We hope to continue to work with MYCOLD to determine how our specialised expertise can further enhance capability uplift beyond surveillance, extending to dam safety risk decision making and dam safety engineering.

A shared commitment to the future

Conferences like ICDSME2025 are timely reminders of our collective responsibility and the shared purpose we need to bring to the challenges ahead. We’re all navigating the same landscape, and when we come together – sharing data, stories and lessons – we accelerate progress for everyone.

I am grateful to MYCOLD for the invitation to contribute and for the generous knowledge-sharing throughout the event. I left Sarawak optimistic: the connection, commitment and collaboration across our sector have never been stronger as we work toward our common goal: safer, more sustainable dams and hydropower systems that support resilient futures.

FIND OUT MORE ABOUT AMANDA

Can you trust advanced tools without qualified professionals behind them?

To make confident decisions about renewable energy assets – from building a wind farm to monitoring dam performance or optimising asset management – owners and operators need precision data they can trust.

As the renewable energy sector becomes increasingly digitised, the quality of measurements matters more than ever. Digital twins, predictive analytics, AI-driven performance tools and remote operations all depend on reliable, precise and traceable data.

Good data provides visibility. It lets owners and operators detect faults or safety issues early, optimise performance, and protect reliability and revenue. For example, accurate turbine alignment during installation or refurbishment could save hundreds of thousands of dollars in downtime and maintenance.

However, data only provides value if it has the right level of accuracy for the job intended. If the data isn’t up to scratch, the decisions won’t be either.

Keeping pace with technology is a steep learning curve

Surveying has always been the backbone of infrastructure development, land management and industrial precision. From the early days of using theodolites and chains to today’s cutting-edge technologies like laser scanning, UAV photogrammetry and LiDAR, the discipline has evolved dramatically. Yet, one constant remains: the need for appropriately qualified and experienced professionals.

Surveying is far more than measuring distances – and achieving precision requires more than sophisticated instruments. It requires a deep understanding of geodesy, data integrity, error propagation and spatial analysis. Traditional instruments such as theodolites and total stations demand mastery of angular measurement and trigonometric principles. GNSS-based methods introduce complexities like satellite geometry, atmospheric corrections and datum transformations. As technology advances, the learning curve steepens: laser scanners and UAVs generate massive point clouds, while LiDAR systems demand expertise in filtering, classification and 3D modelling.

Surveying principles now extend beyond land and construction into industrial metrology, where precision is measured in microns rather than millimetres. In the renewable energy sector, the applications are vast, from assessing hydropower turbine blade wear and integrity of concrete structures to verifying the verticality of wind turbines and ensuring accurate positioning of new hydraulic equipment. Here, advanced techniques like laser trackers and terrestrial laser scanning dominate, and the margin for error is extremely small.

Precision gives confidence that the data feeding an asset’s digital models is accurate, consistent and aligned with recognised standards. When survey instruments, operational sensors and digital monitoring systems all work within a strong metrological framework, asset owners can be confident that their decisions are based on fact, not noise.

The human behind the technology

However sophisticated today’s measurement tools and technologies may be, their outputs are only as trustworthy as the professionals behind them.

Without properly qualified and experienced operators, advanced tools can become liabilities rather than assets. Misinterpretation of data or incorrect calibration can lead to costly errors in construction, infrastructure alignment or asset management.

Using the wrong technique or sensor for the use case and conditions, neglecting appropriate calibration, and a lack of adequate redundancy can lead to major issues and costly mistakes.

Specialised, qualified professionals will think through these issues early, ensuring that accuracy and tolerance requirements are clearly defined from the start and that data integrity is maintained throughout with robust quality control and assurance procedures.

Human insight provides the environmental and engineering context and assurance that automated systems alone cannot deliver. Surveying and metrology professionals can determine whether readings are valid and offsets are accounted for – and will be able to distinguish genuine change from measurement anomalies.

Ultimately, it is professional judgement that transforms accurate data into actionable insights and confident decisions.

Accuracy drives advantage

Today’s surveying advances are transforming how decisions are made. Spatial data is no longer just a technical input; when validated and interpreted by qualified professionals, it becomes a valuable source of real strategic insight and advantage. When the data is right from the start, every subsequent step becomes more certain and the outcomes have the best chance of being more efficient and sustainable. Such clarity can be the difference between success throughout an asset’s lifecycle and expensive lessons learned.

As technologies advance, so does the need for qualified professionals who understand both the science of measurement and the realities of complex, dynamic infrastructure. By ensuring accuracy, compliance with standards and efficient workflows, the qualified surveyor safeguards projects from financial and reputational risks – enabling the reliability, safety and commercial confidence that every asset owner depends on.

If you’d like to talk to us about the potential of advanced surveying and metrology on your project, contact Phillip Ellerton or a member of our Spatial & Data Services Team.

New technologies are important tools, but they need to be used properly

Entura’s Technical Director (Water), Richard Herweynen, recently attended the 2025 ICOLD Congress in Chengdu, China, themed ‘Common Challenges, Shared Future, Better Dams’. Here he shares his observations on the state of play in the international dams industry – and the opportunities emerging with artificial intelligence and automation.

My first ICOLD Congress was in Beijing, China in 2000. I was presenting some finite element analysis work that I had done on Gordon Dam, a 140m-high concrete arch dam in Tasmania. The analysis was being used to help predict and explain some cracks that had formed at the base of the downstream face of the concrete shell, roughly normal to the foundation, during first filling. In the 1980s, an attempt had been made to model the crack using finite element modelling, but with little success due to the coarseness of the mesh. However, by the late 1990s, computing power had increased and finite element programs had improved, providing the capability to construct more detailed finite element models, which were able to predict and explain the cracking that had occurred.

Dr Sergio Giudici, the designer of Gordon Dam, was my mentor on this finite element analysis, and he reinforced these principles:

1. It is important to verify the input data to make sure the model represents, as well as possible, the actual dam parameters.
2. Results should be validated using alternative techniques to give the engineer confidence in the results that the model is producing (i.e. structural hand calculations still have a place).
3. Complexity should be built into these models only gradually, so that the engineer can see the impact of changes and determine whether they are reasonable.

These same principles are true for many complex engineering models and when setting up calculation spreadsheets or similar.

Now, 25 years on, I have had the privilege of attending the 2025 ICOLD Congress in Chengdu, China. At this Congress, there was much talk about the importance of dams in society for water security, the growing role dams and reservoirs play in providing resilience to climate change and the energy transition, the importance of balancing economic benefits and environmental needs, and – in all of this – the importance of ensuring that our dams are safe for communities downstream.

We have discussed many of these themes before – and they remain highly important; however, one thing I took away from ICOLD 2025 in particular was how China is embracing technology and advancing a ‘Smart Dam’ initiative.

New technologies and smarter dams

One could say that our industry has always been building smart dams, but China’s ‘Smart Dam’ concept is about using the full power of current technologies to construct, monitor and operate dams in smarter ways, and to use technologies to predict and adapt to changing conditions.

The CHINCOLD Workshop on Digital and Intelligent Technologies for Dam Construction, Operation and Maintenance, which occurred during ICOLD 2025, gave a glimpse of what may be possible.

Many projects utilise 3-dimensional digital models and building information modelling (BIM). However, the concept of having a digital twin of the dam, replicating every aspect of the physical dam in a digital form, opens the door to many possibilities, especially in light of the advent of artificial intelligence (AI).

Artificial intelligence and machine learning

Many organisations and nations have been cautious about AI, but China is increasingly adopting it to improve construction practices in dam engineering, improve monitoring and surveillance of dams, and to help adapt to extreme events as they occur.

Machine learning (ML), an element of AI, enables computers to learn from data without being explicitly programmed. ML algorithms analyse data, identify patterns, and make predictions or decisions, improving their performance over time and with more data. There are no doubt many engineering applications where ML could be used to help improve predictive modelling or optimisation, and to make these more efficient. However, the same principles that were important when we were beginning to embrace larger, more refined finite element models with the advent of faster computing remain true here:

1. We must verify the input data that machine learning is utilising to ensure we don’t get ‘garbage in equals garbage out’.
2. Results need to be validated. AI needs to be trained correctly, and we need experts involved at this stage to ensure that the outputs from AI are correct.
3. Complexity, or the full power of technology, should be added incrementally, to provide progressive confidence in the outcomes.

Engineering is the application of science, and therefore it is critical for every engineer to understand the fundamental principles and how to apply them. The complex computer programs used for a lot of engineering modelling can become ‘black boxes’, and practitioners risk diluting or losing their understanding of the fundamental principles behind the models, and hence their ability to validate the results.

Automation brings a step change in efficiency and accuracy

At the ICOLD Congress in 2000, I co-authored a paper for the international symposium on concrete-faced rockfill dams (CFRD) entitled ‘Hydro Tasmania experience in concrete-faced rockfill dams – past, present and future’. There is no doubt that Hydro Tasmania has a strong history in CFRD, with Cethana Dam playing an important role in the development of the modern, high CFRD.

In 2000, however, the future in CFRD that we envisaged did not include unmanned construction equipment with automatic quality control feedback loops. At the 2025 CHINCOLD Workshop on Digital and Intelligent Technologies for Dam Construction, Operation and Maintenance, a presentation was given by Wang Jiajun from Tianjin University on intelligent unmanned roller systems to compact rockfill dams. Unmanned rolling compaction (URC) systems involve three core technology modules: (1) intelligent perception, (2) autonomous planning and decision making, and (3) intelligent control.  These systems use automated driving technology to control the rolling process on earth and rockfill dams, improving productivity and quality. They can accurately control compaction parameters such as passes, speed, vibration and lift thickness. URC systems also enable continuous monitoring and real-time feedback for quality control, reducing human error and improving overall project performance. This automated technology was used on the 295m-high, 1.57km-long Lianghekou hydropower dam in China, with a total fill volume of 43 million m³.

The changing face of dam engineering

With AI and automation, the scope for embracing new technology in dam engineering is growing fast. It is clear that there are significant benefits that could be realised for dam design, construction, operation, dam safety and emergency response – and there’s a role for these advanced technologies at all of the stages of the life cycle of a dam. A degree of caution is appropriate and necessary, but caution should not be a reason to refuse to engage with the new technologies available to our industry.

However, with more sophisticated models – such as digital twins – being created of our dams, it is important to ensure we maintain the guiding engineering principles of verifying input data, validating models for correctness, and building complexity gradually. By doing this, we can provide the necessary assurance and confidence in our increasingly sophisticated and evolving tools.

ABOUT THE AUTHOR

Richard Herweynen is Entura’s Technical Director – Water. He has more than three decades of experience in dam and hydropower engineering, working throughout the Indo-Pacific region on both dam and hydropower projects. His experience covers all aspects including investigations, feasibility studies, detailed design, construction liaison, operation and maintenance and risk assessment for both new and existing projects. Richard has been part of a number of recent expert review panels for major water projects. He participated in the ANCOLD working group for concrete gravity dams and was the Chairman of the ICOLD technical committee on engineering activities in the planning process for water resources projects. Richard has won many engineering excellence and innovation awards (including Engineers Australia’s Professional Engineer of the Year 2012 – Tasmanian Division), and has published more than 30 technical papers on dam engineering.

Planning for the future – the challenges of dam inspection and maintenance

No dam is ‘maintenance free’. Without appropriate maintenance and refurbishment at the right times, a dam may not be able to fulfil its function safely for the full length of its design life (which could be more than a century).

This presents many challenges for asset owners. To keep the dam operating as the designer intended – and get the most out of the original investment over the long term – owners will need to develop and implement a suitable operations and maintenance manual aligned with the asset management plan and reflecting a ‘whole of life’ strategy. These plans will need to consider the unique characteristics of each dam and cover all the relevant issues. And there are many!

Dams consist of a number of different elements. There are the main civil engineering components including the wall that holds back the water and the spillway – but there could also be mechanical elements (pipework, valves and gates) and electrical elements (power supply to lights, valves, gate motors and control systems). Each of these elements will have its own operational and maintenance requirements and different lifecycle duration. Ideally, all this detail needs to be captured in the operation and maintenance manual (as recommended by ANCOLD guidelines) and in an asset management plan.

Civil components

The civil components of dams have the longest life span, typically more than 100 years if well constructed and maintained. Common maintenance items that need to be regularly addressed include:

• Vegetation management

Trees and bushes will readily grow in earthfill and rockfill embankments. Regular control (e.g. annually) is necessary to ensure that roots don’t grow through the fill and initiate leaks through the embankment. Mowing the grass on the downstream face of the earthfill embankment and downstream contact is necessary so that the condition of the face can be observed. Even concrete gravity and concrete arch dams will require vegetation control along the downstream face contact with the foundation so that the dam can be easily viewed in routine inspections.

• Surface water drainage

Dam construction typically affects natural drainage lines, which is why surface water drains are a common feature around and on dams – such as along the groins (where the dam wall intersects with natural ground), along berms in embankment dams, along benches, at the top of cuttings, and along access tracks. Drains will need regular inspection for both erosion and blockage due to sediment or vegetation.

• Foundation drain cleaning

Concrete gravity dams and concrete arch dams typically have drains drilled into the rock foundations to relieve uplift pressures and help maintain stability of the wall. Over time, silt or iron-rich slime can build up as a byproduct of bacterial growth in the drains, reducing effectiveness. These drains typically require 5-yearly high-pressure flushing. Cleaning will also be needed for drains underneath spillways founded on rock and cut slopes in rock.

• Protection of the dam safety monitoring system

Protecting the dam safety monitoring system requires a range of regular activities. These include cleaning and clearing vee-notch seepage monitoring weirs, checking survey monitoring pillars and targets, and checking the calibration of level monitoring and indication devices, such as reservoir-level sensors, piezometers, tiltmeters and inclinometers. Regular functional testing will also need to be carried out on the alarming and tripping devices that form the primary protection elements of the dam, including spillway gates and scour valves.

• Clearing of trash racks

Outlet works usually have trash racks to stop debris entering the pipework and causing blockages. It’s important to check that the build-up of debris is tolerable and that any hydraulic losses won’t affect operations. Assessing and removing the debris isn’t easy, as the trash racks are often accessible only by remotely operated vehicles (ROVs) or by divers. Before the inspection, the outlet will typically need to be closed and isolated.

Inspection-driven longer term maintenance will also be required for particular elements of the dam, ideally addressing repair items promptly to minimise damage and the cost of future repairs if left untreated. For example, concrete repairs may be needed to address erosion in stilling basins and spillway chutes, or spalling of concrete due to reinforcement corrosion or freeze/thaw damage.

While regular inspections should be undertaken to detect slow deterioration, special inspections following major events – such as floods or earthquakes – should also be part of the operations and maintenance plan. Given that the key areas for inspection are often difficult to access safely, use of UAVs (e.g. to inspect a spillway crest and chute) or ROVs (e.g. to undertake underwater inspections or scanning of stilling basins, plunge pools or riverbed scour) should be considered.

When special inspections identify the need for repairs, the time is right to consider whether the dam’s design or surveillance could be improved to increase resilience for a similar event in future. For example, a higher strength concrete overlay may treat erosion of a spillway chute and increase its resistance to future erosion.

Mechanical components

Mechanical items such as steel or cast-iron pipework can also often last up to 100 years if adequately protected from corrosion. Concrete and cement mortar are very effective for this purpose as the alkaline environment provided by the cement paste provides a very low corrosion environment. Key to the effectiveness of this protection is ensuring that the cement remains in intimate contact with the steel or iron. This will require regular inspections and timely repairs. Where concrete protection is not practical, paint systems can be very effective for up to about 20 years. A suitable inspection regime will be needed so that any areas where the paint has deteriorated can be detected and patched.

Mechanical items such as valves and gates typically have an effective life of around 50 years; however, they need to be exercised regularly to keep them able to work on demand. This is not an issue of the parts wearing out from use; rather, it’s the risk of them seizing due to lack of use. Regular lubrication of bearings, gearboxes and trunnions needs to be included as part of the maintenance of these items. This is particularly important in scour valves and spillway gates that may have a very low frequency of use during normal operations but are there for use in emergencies. The wire ropes commonly used to hoist spillway gates open will need even more frequent replacement, at approximately every 20 years.

Electrical components

Electric motors are commonly used to drive the winches hoisting spillway gates or driving the shafts to open valves. Associated with the motors will be switchboards and power supply systems, typically including grid power supply and backup diesel generators. The typical life of these components is around 25 years. As with the mechanical components, lack of operation can lead to premature failure, so a regular regime of exercise is necessary to ensure maximum reliability and life.

The programable logic controllers (PLC) that are used to automate operations, allow remote operations and generate alarms will have a typical life of only 10–12 years due to changes in programming languages and rapid evolution of the hardware. 

Getting the most out of life

As we’ve seen, regular maintenance is fundamental for keeping all the components of a dam operating as intended and maximising their lifespan – whether that’s 10 years or 100. This maintenance, including the exercising of the mechanical and electrical components, needs to be clearly documented in the operations and maintenance manual and recorded in an asset management system. The asset management plan must allow for regular maintenance and also budget appropriately for replacement or refurbishment when any component of the dam is due for retirement.

At Entura, we believe in getting the most out of every piece of infrastructure because that’s good for our clients, communities and the planet. With a solid regime of inspection and maintenance, all the parts of your dam will be on the strongest path to a long, reliable and sustainable life.

If you’d like to talk with us about inspecting and maintaining your dam/s, contact Phil Ellerton, Paul Southcott, or Richard Herweynen.

About the author

Paul Southcott is Entura’s Senior Principal – Dams and Headworks. Paul has an outstanding depth of knowledge and skill developed over more than 3 decades in the fields of civil and dam engineering. He is a highly respected dams specialist and was recognised as Tasmania’s Professional Engineer of the Year in Engineers Australia’s 2021 Engineering Excellence Awards. Paul has contributed to many major dam and hydropower projects in Australia and abroad, including Tasmania’s ‘Battery of the Nation’, the Tarraleah hydropower scheme, Snowy Hydro, and numerous programs of work for water utilities including SeqWater, Sun Water and SAWater. His expertise is a crucial part of Entura’s ongoing support for upgrade and safety works for Hydro Tasmania’s and TasWater’s extensive dams portfolios. Paul is passionate about furthering the engineering profession through knowledge sharing, and has supported many young and emerging engineers through training and mentoring.

‘Dams for People, Water, Environment and Development’ – some reflections from ICOLD 2024

Entura’s Amanda Ashworth (Managing Director) and Richard Herweynen (Technical Director, Water) recently attended the International Commission on Large Dams (ICOLD) 2024 Annual Meeting and International Symposium, held in New Delhi. Amanda presented on building dam safety capability, skills and competencies, while Richard presented on Hydro Tasmania’s risk-based, systems approach to dam safety management, and the importance of pumped hydro in Australia’s energy transition. 

Here they share some reflections on ICOLD 2024 …

Richard Herweynen – on the value of storage, ‘right dams’, and stewardship

At ICOLD 2024 we were reminded again that water storages will be critical for the world’s ability to deal with climate change and meet the growing global population’s needs for food and water. We can expect greater climate variability and therefore more variability in river flows, which means that more storage will be needed to ensure a high level of reliability of water supply. Without more water storages to buffer climate impacts, heavily water-dependent sectors like agriculture will be impacted.

To slow the rate of climate change, we must decarbonise our economies – but without significant energy storage, it will be difficult to transition from thermal power to variable renewable energy (wind and solar). Pablo Valverde, representing the International Hydropower Association (IHA), said at the conference that ‘storage is the hidden crisis within the crisis’. There was a lot of discussion at ICOLD 2024 about pumped hydro energy storage as a promising part of the solution. It is also important, however, to remember that conventional hydropower, with significant water storage, can be repurposed operationally to provide a firming role too. Water storage is the biggest ‘battery’ of the world and will be a critical element in the energy transition.

With the title of the ICOLD Symposium being ‘Dams for People, Water, Environment and Development’, I reflected again on the need for ‘right dams’ rather than ‘no dams’. ‘Right dams’ are those that achieve a balance among people, water, environment and development. In the opening address, we were reminded of the links between ‘ecology’ and ‘economy’ – which are not only connected by their linguistic roots but also by the dependence of any successful economy on the natural environment. It is our ethical responsibility to manage the environment with care.

When planning and designing water storages, we must recognise that a river provides ecological services and that affected people should be engaged and involved in achieving the right balance. If appropriate project sites are selected and designs strive to mitigate impacts, it is possible for a dam project’s positive contribution to be greater than its environmental impact, as was showcased in number of projects presented at the ICOLD gathering. Finding the balance is our challenge as dam engineers.

The president of ICOLD, Michel Lino, reminded delegates that the safety of dams has always been ICOLD’s focus, and that there is more to be done to improve dam safety around the world. At one session, Piotr Sliwinski discussed the Topola Dam in Poland, which failed during recent floods due to overtopping of the emergency spillway. Sharing and learning together from such experiences is an important benefit of participating in the ICOLD community.

Alejandro Pujol from Argentina, who chaired one of the ‘Dam Safety Management and Engineering’ sessions, reflected that in ICOLD’s early years the focus was on better ways to design and construct new dams, but the spotlight has now shifted to the long-term health of existing dams. It is critical that dams remain safe throughout the challenges that nature delivers, from floods to earthquakes. In reality, dams usually continue to operate long beyond their 80–100 year design life if they are structurally safe, as evidenced in the examples of long-lived dams presented by Martin Wieland from Switzerland. He suggested that the lifespan of well-designed, well-constructed, well-maintained and well-operated dams can even exceed 200 years. As dam engineers, no matter the part we play in the life of a dam, we have a responsibility to do it well.

From my conversations with a number of dam engineers representing the ICOLD Young Professional Forum (YPF), and seeing the progress of this body within the ICOLD community, I believe that the dam industry is in good hands – although, of course, there is always more to be done. I was pleased to see an Australian, Brandon Pearce, voted onto the ICOLD YPF Board.

Another YPF member, Sam Tudor from the UK, reminded us in his address of the importance of knowledge transfer, the moral obligation we all have especially to the downstream communities of our dams, and our stewardship role. He was referencing his experience of looking after dams that are more than 120 years old – all built long before he was born. Many of our colleagues across Entura and Hydro Tasmania feel this same sense of responsibility and pride when we work on Hydro Tasmania’s assets, which were built over more than a century and have been fundamental to shaping our state’s economy and delivering the quality of life we now enjoy. It is up to all of us to carry the positive legacy of these assets forward with care and custodianship, for the benefit of future generations.

Amanda Ashworth – on costs and benefits, dam safety, and an inclusive workforce

Like Richard, I found much food for thought at ICOLD 2024. For me, it reinforced the need to accelerate hydropower globally, particularly in places where the total resource is as yet underdeveloped. To do so, we will need regulatory frameworks that support success – such as by monetising storage and recognising it as an official use – and administrative reforms that ease the challenges of achieving planning approvals, grid connection agreements and financing for long-duration storage. We must encourage research and development to move our sector forward: from multi-energy hybrids to advanced construction materials and innovations to improve rehabilitation.

In particular, I’ve been reflecting on how our sector could extend our thinking and discourse about the impacts and benefits equation beyond the broad answer that dams are good for the net zero transition. How can we enact and communicate the many other potential local environmental and social benefits and long-term value from dams?

Much of the world’s existing critical infrastructure came at a significant financial expense as well as social and environmental costs – so it is our obligation to pay back that investment by maximising every dam’s effective life. When we invest in extending the lifespan of dam infrastructure through effective asset management and maintenance, and when we maximise generation or the value of storage in the market, we increase the ‘return on investment’ against the financial, social and environmental impacts incurred in the past.

Of course, the global dams community must continue to prioritise dam safety and work towards a ‘safety culture’. I was pleased to hear Debashree Mukherjee, Secretary of the Ministry of Jal Shakti, celebrate the progress on finalising regulations across states to enact India’s Federal Dam Safety Act and establishing two centres of excellence to lift capacity across the nation. Dam safety depends on well-trained people with the right skills and competencies to comply with evolving standards, apply new technologies, and respond effectively to changing operational circumstances and demands. 

I also enjoyed hearing from ICOLD’s gender and diversity committee on its progress, including updates from around 14 nations on their efforts to build a more inclusive renewable energy and dams workforce. This is front of mind for us, as we step up Entura’s own focus and actions on gender equity throughout our business this year.

The challenges facing our dams community – and our planet – are enormous, but there is certainly much to be excited about, and we look forward to continuing these important conversations over the next year.

From Richard, Amanda and Entura’s team, many thanks to the Indian National Committee on Large Dams (INCOLD) for organising and hosting this year’s ICOLD event, supporting our sector to build international professional networks, and facilitating the sharing of experiences and knowledge across the globe – all of which are so important for growing the ‘ICOLD family’ and supporting a safer, more resilient and more sustainable water and energy future.

Designing dams for an uncertain climate future

Dams are critical infrastructure for water supply, irrigation, energy production, flood protection, or multiple purposes. They are usually designed to last at least 100 years, yet with good maintenance and appropriate dam safety practices, dams can continue to perform as designed for centuries. But what about climate change? The circumstances in which a dam operates may be very different in the coming decades – and exactly how these changes will play out in different regions is impossible to predict with certainty. 

Dams are designed to continue to perform safely in extreme events, such as major floods and earthquakes, to avoid the high economic, environmental, and social consequences of dam failure. When the consequence has the potential to be extreme, the flood that the dam will need to be designed for is, in Australia, the ‘Probable Maximum Flood’ (PMF), while in some other parts of the world it is often the 1:10,000 annual exceedance probability (AEP) flood.

But even if standards or guidelines are clear about the ‘return period’ of flood that the dam should be designed for – is it still as simple as reading the magnitude of the flood discharge off the flood frequency curve as has been done in the past? These days, it is not so simple. 

Exploring the inherent uncertainty in the flood frequency curve

Part of the reason for more complexity is that we have greater computing power today to be able to explore the uncertainty in our flood frequency curve.  Predicting extreme flood events (such as the PMF) is not an exact science and involves many variables which are often not well characterised. As a result, there is significant uncertainty in predicting floods, particularly extreme floods. If this uncertainty is presented, the flood frequency curve is no longer a single line but a band. The more extreme the flood event, the wider the uncertainty band. Although the flood frequency curve shown below is fitted directly to measured flow data, the uncertainty bounds are similar regardless of the approaches implemented to derive the flood frequency curves.

So, what flood should the dam be designed for? Should it be the median best estimate, or should it take into account some of the uncertainty? This is the first challenge, and it is there whether we consider climate change or not.

Adding the extra uncertainty of climate change

Climate change doesn’t stand still. This adds even more complexity to the flood prediction challenge. What is the impact of climate change on extreme events now, and what will it be as time goes by? Numerous studies of climate change impacts suggest that there will be greater variability in extreme temperatures and extreme rainfall, and that extreme events may become more frequent. As a result, the magnitude of extreme flood events, for which dams must be designed, will likely increase with time.

Changes in the magnitude or frequency of extreme floods will depend on projections of future temperature, emission scenarios and the models used to simulate the changes. Even with a ‘middle of the road’ emission scenario (such as the IPCC’s SSP2–4.5 scenario) that results in a median global temperature increase of 3 °C (compared to preindustrial temperature baseline) by the end of this century, there could be a 23% increase in 24-hour extreme rainfall depth. But this is only one of the scenarios; some are more extreme, some show less increase, some show more. The increase is greater for higher emission scenarios and for shorter duration storms. Ultimately, an increase in rainfall depths results in an increase in flood magnitudes.

Guidance on climate uncertainty in dam design is limited

Currently, most standards and guidance documents are silent on how climate change should be applied in the design of spillway capacities for dams to safely pass these extreme flood events. However, the International Commission on Large Dams (ICOLD) Bulletin 142 on the Safe Passage of Extreme Floods (2012) indicates that there is uncertainty associated with the resulting flood estimates because of uncertainties in the hydrometeorological data used in determining the design flood. In addition, there may be changes in future methods for the development of design floods, changes in the future condition of the catchment (e.g. due to deforestation), and changes in rainfall conditions due to climate change. All of these have the potential to increase the magnitude of the future design flood.

This 2012 bulletin encourages strategies for planning spillway arrangements with consideration of floods exceeding the design flood (i.e. checking the robustness of the spillway flood design capacity from a dam safety risk perspective). This demonstrates that more than a decade ago the international dam engineering community was already promoting consideration of climate change resilience when designing new dams and upgrades of existing dams.

The more recent ICOLD Bulletin 170 on Flood Evaluation and Dam Safety (2018) states that although projected changes in climate are generally expected to increase flood risk in many parts of the world, understanding the impact on flood risk is subject to considerable uncertainty. It states that one of the main impacts of climate change will be to increase the uncertainty associated with the estimation of extreme floods.

There are tools available now that can be used to look at climate change impacts on extreme rainfall events, mainly around changing rainfall inputs to rainfall–runoff models based on climate advice, or else through using stochastic climate generators. However, this 2018 ICOLD bulletin also warns about complex numerical modelling and the ‘black box effect’ of accepting results without verification or critical consideration. It stresses that the intrinsic hydrological uncertainty will always remain no matter how clever or complex the numerical modelling.

Practical suggestions for dealing with uncertainty

Given that dams are designed for the long-term, it is crucial to consider the uncertainty of floods and the potential impacts of climate change. Climate impacts are being discussed increasingly by dam owners, dam engineers and dam regulators – and guidance on how best to deal with climate change will come eventually. This review article, ‘Climate change impacts on dam safety’, provides a good summary and some thoughts about approaching the issues in a framework based on dam safety risk.

In the meanwhile, we’ve developed some practical suggestions for dealing with intrinsic hydrological uncertainty and the increased uncertainty due to climate change, whether you’re working on new dams or upgrades to existing dams:

1. 1. Determine the consequence category for the dam. If this is ‘High’ or ‘Extreme’, take a more conservative view as to the acceptable flood capacity.
2. 2. Try to quantify the uncertainty, based on current climate conditions, as part of any flood study for a new dam or the updated flood study for an existing dam as part of a dam safety review. The Monte Carlo simulation approach to flood estimation is very useful in this regard.
3. 3. Consider some of the additional uncertainty due to climate change, based on various future climate change scenarios using GCM modelling for the region in which the dam is located.
4. 4. Undertake sensitivity assessments for spillways for new dams, or upgrades to spillways on existing dams, based on the uncertainty presented in the extreme flood events.
5. 5. If the incremental cost increase to the overall project cost is relatively low for increasing the spillway capacity to accommodate climate uncertainty, build resilience into the design as suggested by ICOLD Bulletin 142.
6. 6. If the incremental cost is significant, apply the ALARP principle for upgrades to existing dams. For new dams, assess the likely benefits and costs in detail using a risk-based framework (and consider suggestion 8 below).
7. 7. For an existing dam or new dam, consider the opportunity to stage a spillway upgrade such that the dam is made compliant for the current climate scenario with planned future upgrades that allow flexibility to meet future climate scenarios.
8. 8. Where decisions about designing for climate uncertainty become complex, consider an independent technical review panel to provide appropriate technical governance on a risk-based decision.

If you would like to speak with us about how climate change could affect your new or existing dam, please contact Richard Herweynen or Prafulla Pokhrel.

About the author

Richard Herweynen acknowledges the input of his colleagues Prafulla Pokhrel (Principal Consultant, Hydrology) and Paul Southcott (Senior Principal, Dams and Headworks) in writing this article.

Richard is Entura’s Technical Director, Water. He has more than three decades of experience in dam and hydropower engineering, and has worked throughout the Indo-Pacific region on both dam and hydropower projects, covering all aspects including investigations, feasibility studies, detailed design, construction liaison, operation and maintenance and risk assessment for both new and existing projects. Richard has been part of a number of recent expert review panels for major water projects. He participated in the ANCOLD working group for concrete gravity dams and was the Chairman of the ICOLD technical committee on engineering activities in the planning process for water resources projects. Richard has won many engineering excellence and innovation awards (including Engineers Australia’s Professional Engineer of the Year 2012 – Tasmanian Division), and has published more than 30 technical papers on dam engineering.

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