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.

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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.

MORE THOUGHT LEADERSHIP ARTICLES

Dams are crucial to climate change response and the energy transition

At the recent ICOLD meeting in Gothenburg, Sweden, dam engineering experts from across the globe came together to share knowledge, discuss trends and issues, and engage with each other. One important topic of discussion was the role of dams in the international response to climate change and what that will mean for the dams industry. Richard Herweynen, Entura’s Technical Director, Water, shares his thoughts on this topic here …

Why will dams play a critical role?

Three major reasons why dams will be crucial in the climate change response and energy transition are water security, dispatchability of electricity, and tailings storage.

1. Water storages will be vital to provide the same level of water security

Water security is essential for humanity. With greater hydrological variability due to climate change, more storage will be needed to provide the same level of security of water, food and energy. Water storage is a fundamental protection from the impacts of a changing climate, safeguarding the supply of water, and the water–food–energy nexus, even during extended drought.

The effects of climate change are predicted to increase and to result in greater magnitude and frequency of hydrological extremes, such as prolonged droughts and significant floods. With prolonged drought, inflows to storages will reduce. If demand remains the same, stress on existing water storages will increase.

Water storages are used to regulate flows and manage this variability: storing water when there are high inflows (or floods) and then using this stored water during low inflows (or droughts). Dams are used to create these vital water storages.

2. Hydropower and pumped hydro energy storage (PHES) are critical for the energy transition

A key response to climate change is the decarbonisation of the electricity sector through renewable energy. Wind and solar power now offer the lowest cost of energy, have low ongoing operational costs, and emit the least greenhouse gases across their lifecycle – and therefore hold the greatest potential for rapid decarbonisation of the energy sector. Of course, wind and solar PV output vary according to the weather and the time of day – but the electricity market needs the supply of electricity to match demand, or for these renewables to be dispatchable.

Energy storage is the key to smoothing out the variability of renewable energy generated by solar and wind. The power and duration of the storage are the two key variables in determining the most suitable solution. Low-power, short-term storage is currently more cost-effective using batteries, but longer periods and larger power requirements are likely to rely on bigger storage options, such as pumped hydro energy storage (PHES) and traditional hydropower. Smoothing out the daily variability in renewables can be achieved effectively through pumped hydro. Dams are used to create the water storages used in both traditional hydropower and PHES.

3. The transition to renewables will demand more minerals and metals

The global energy transition will demand a major increase in renewable energy technologies – which in turn will require more of the ‘critical energy minerals’ and metals. The rising need for minerals such as copper, aluminium, graphite, lithium and cobalt will not be able to be met by recycling and reuse alone. Therefore, extraction and storage of minerals from mining operations will be essential to sustain the renewable energy transition.

According to a report by the World Bank Group, the production of minerals such as graphite, lithium, and cobalt could increase by nearly 500% by 2050 to meet the escalating demand for clean energy technologies. It is estimated that over 3 billion tonnes of minerals and metals will be necessary for the deployment of wind, solar, geothermal power and energy storage, all of which are vital for achieving a sustainable future with temperatures below 2°C.

However, this need for mining activity comes with a special responsibility for sustainable practices, including the proper management and storage of mining waste. Rock, soil and other by-products are left behind after the desired minerals have been extracted from the ore. Tailings facilities store this waste, playing a crucial role in mitigating the environmental impact of mining operations. Dams, in particular, are commonly used to create these facilities, as they provide an effective means of containing the waste.

Dams used in tailings facilities are designed to withstand the weight and pressure of the waste materials, prevent seepage of contaminants into the surrounding environment, and take into account factors such as stability, erosion control and water management. Dams that are well designed, constructed and monitored, adhering to stringent environmental and safety regulations, can help prevent the spread of mining waste into nearby water bodies, reducing the risk of water contamination and protecting aquatic ecosystems.

Working towards ‘good dams’

While there have certainly been some examples around the world of dams that have had adverse impacts, it is clear that dams will play a critical role in the international response to climate change and the decarbonisation of the energy sector. It’s therefore vital that dams are planned, constructed and managed appropriately and safely. With increasing understanding of impacts and far greater sophistication of internationally accepted sustainability protocols, it is now up to developers and planners to heed the lessons of the past and find the right dam sites for nature and communities.

It is important that we ensure the safety of existing dams as well as the safety of any new dams. Examples from around the world demonstrate the devastating consequences of dam failures. Safety must be every dam owner’s key concern, and should be managed through an active dam safety program.

Of course, the larger the portfolio of dams an owner is managing, the greater the demand on their resources; however, it is critical that dam safety risks for water storages and tailings facilities are managed appropriately across dam portfolios to protect downstream communities. The Portfolio Risk Assessment process increases the focus on potential failure modes and risk as drivers of the dam safety program and as the basis for deciding priorities for allocating operational and capital resources.

It will also be vital that dams engineers, owners and operators keep up to date with the latest developments in the dams industry worldwide through continuous learning and important global forums such as ICOLD.

If you’d like to talk with Entura about your water or dam project, contact Richard Herweynen.

About the author

Richard Herweynen is Entura’s Technical Director, Water. Richard has 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 is 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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Planning sustainable water infrastructure in a changing world

In an already water-stressed world and a rapidly changing climate, water is increasingly precious. To manage and control this vital resource, we must create and maintain safe, reliable and sustainable water infrastructure – and such a challenge calls for good planning.

The International Commission on Large Dams is working towards releasing new guidance for water infrastructure planning – and Entura’s Richard Herweynen is a member of the Technical Committee looking to develop a new ICOLD Bulletin on planning. In this article, Richard explains the importance and evolution of planning approaches.

Water infrastructure projects deliver the dams, treatment plants, irrigation systems and distribution networks that provide water for homes, food production, industries and emergencies. They also create the structures integral for mitigating the effects of floods and droughts. But to maximise the benefits of this infrastructure, projects must be planned, engineered and managed for effectiveness, safety and sustainability.

These projects are far too important to approach in a haphazard way. Planning offers a structured, rational approach to solving problems – and it is the start of the ‘pipeline’ for addressing water resource needs and competing demands. In fact, for civil works programs, everything begins with planning.

Without a good plan, where are we?

Without careful planning, it can be difficult to achieve creative, cost-effective solutions to water needs. The planning stage helps decision-makers identify water resource problems, conceive solutions and evaluate the inevitably conflicting values inherent in any solution. Planning is best done by a team that brings together specialists in many of the natural, social and engineering sciences.

At the planning stage, all of the following points should be thought through:

Guidance for better planning

In 2007, I became the ANCOLD-nominated member on a new Technical Committee for the International Commission of Large Dams (ICOLD) entitled ‘Engineering Activities in the Planning Process for Water Resource Projects’. In 2009 we put forward a position paper setting out an ‘Improved Planning Process for Water Resource Infrastructure’ based on ‘comprehensive vision based planning (CVBP)’.

At the next ICOLD Annual Meeting in Sweden in June 2023, our committee will be meeting to work on an updated framework that takes into account the rapid change we’ve witnessed over the last decade and the many cross-cutting issues that are impacting the planning process, such as risk-informed decision-making, climate change, sustainable development, environmental concerns, and river basins/systems.

What is ‘comprehensive vision-based planning’ (CVBP)?

Before we talk about updates, let’s take a quick look at our existing approach to CVBP, as articulated in 2009.

CVPB is a comprehensive, transparent planning process based on a shared vision for sustainable water resource development. It aims to achieve a better ‘triple bottom line’ outcome, with optimum economic, social and environmental outcomes.

Whereas many past projects were planned on a case-by-case basis, CVBP looks beyond the immediate project to the broader regional vision and watershed goals (which may also cross national borders), taking projected changes in water supply and demand into account. It draws on integrated water resources management (IWRM) to consider multiple points of view about how to manage water and to view each water infrastructure project in relationship to the other existing infrastructure in the region.

CVPB also incorporates much greater attention to the realistic options and cost-benefits of mitigation of environmental impacts – and it draws in more interdisciplinary engineering, cost estimating, and stakeholder/community engagement.

CVBP is, therefore, a holistic, integrated and collaborative approach to planning and a much-improved pathway towards successful outcomes.

The 8 steps of CVBP

As currently articulated, CVBP has 8 defined steps – but it’s an iterative process in which steps 2 to 7 are repeated multiple times, as necessary. The 2009 ICOLD bulletin goes into much greater detail than we can in this article, but this will give you an overview:

Changes moving forward

It is time to update the planning process and guidance in the light of the rapid changes we are experiencing in our environment, innovations in technologies, and an increasing awareness of sustainability and ethics.

In the past, much water infrastructure has been planned within a reasonably near-term political and social lens and timeframe, and from a perspective of relative stability. But we know that change is constant and rapid, so our planning approaches need to shift to an even greater appreciation of uncertainty, risk and the intensifying potential for extreme events. There is also an urgent need to apply a deeper and broader awareness of the many considerations that make for greater environmental, social and economic sustainability.

Important factors here will be an uplift in stakeholder involvement and governance, a very clear focus on the costs and benefits that can’t easily be quantified or monetised, and reinforcement of the fundamental principle of ‘do no harm’.

It will also be important to take an adaptive approach to regional planning objectives, with a strong awareness of different regional and cultural values, goals, expectations, methodologies, financing arrangements and roles of government.

We should expand the planning scenarios to also explore non-structural options, dam removal plans, and scenarios based on failure modes. We also need to improve early data collection by finding and filling data gaps, improving the ways in which we preserve historical information, and improving data portrayal.

It is very important to involve the right people. Ideally, the planning team should be more than ‘multi-disciplinary’ or ‘interdisciplinary’. It should aspire to be ‘transdisciplinary’, in which all disciplines work seamlessly and collectively and achieve a level of insight that is ‘greater than the sum of its parts’.

This year, our Technical Committee will continue to build on some of these elements as we review and rearticulate CVBP, working towards a new ICOLD Bulletin to guide water infrastructure planning.

In a changing world, our approaches to infrastructure cannot stagnate. Designing, articulating and applying new planning frameworks is an important step towards creating and maintaining the sustainable, reliable water infrastructure our planet so urgently needs.

If you’d like to talk with Entura about your water or dam project, contact Richard Herweynen.

About the author

Richard Herweynen is Entura’s Technical Director, Water. Richard has 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 is 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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How robust is your emergency preparedness?

The old adage of ‘a company’s greatest assets are its people’ is never more true than in an emergency situation. The success of any emergency plan depends upon the skills, training and willingness of the people involved. It also relies on robust emergency preparation that takes as many scenarios as possible into account, and builds in a range of backups and alternatives for maximum agility and resilience.

All responsible dam owners have dam safety emergency plans (DSEP) which are carefully created and tailored to the needs of the company, its assets and its available resources.

If called upon in an extreme event, these plans will likely be pushed to their limit – but it’s vital that they perform as intended to reduce risk and consequences downstream.

The ultimate test of the emergency plan is how well it can cope with outages of power and/or communications. ‘Stress testing’ emergency plans for outage scenarios and implications is key to achieving a robust plan.

Power and communications outages

Where dams have moving parts, such as valves or floodgates, backups are needed to counter power outages. Are backup generators in place, or can a portable generator be brought to site at short notice? Is there a clear, safe access route to site during emergency conditions (e.g. not flooded or blocked by fallen trees)? Where this is not possible, can the valves or floodgates be operated by hand? A further question is whether these components are readily operable and exercised regularly. 

Many dams are located in remote areas, and in some cases mobile phone reception is unreliable. In these situations, can satellite phones be made available? Landline phones may be available but depend on poles and lines remaining intact and operable during emergency conditions. 

Communications are vital to ensuring the emergency plans are enacted under the direction of the incident controller. Where communications with remote resources are limited or not possible, those involved must fall back on their training and on lessons learnt from exercises and site-based, staged events involving scenarios of outages of power and communications. The DSEP can be updated with suggested actions for the on-site operators and emergency management team to follow in the worst-case scenario.

Alternative means of communication and access

In situations where check-in communications are required with those working remotely, alternative means must be considered in case of an outage of communications. In the absence of satellite phones, this could involve a messenger driving to site, but this relies on clear, safe access routes and careful consideration of the time required. In extreme cases, the only means of reaching a remote site may be by helicopter. This would require pre-arrangement with the closest helicopter providers regarding emergency availability.

The situation is similar with suppliers of plant and materials that may be required to assist with conditions at or downstream of the dam. How can they be contacted, and is there clear, safe access to site?  Consider having emergency stockpiles at site or nearby and ready access to earthmoving plant.

Decision-making in a SCADA outage

If a power outage results in a localised SCADA outage, there will be no current instrumentation data available to guide critical decisions. In such circumstances, decisions must be based on likely behaviour during emergency conditions or on forecasts from before the emergency is declared. This would likely require detailed knowledge of the dams and their components, which highlights the importance of regular routine monitoring and detailed studies such as comprehensive surveillance reviews and dam safety reviews.

Company culture, teamwork and support

Where there is a ‘no blame’ company culture in which employees are encouraged to speak up, point out flaws in systems and processes and identify faults with assets, there is a greater likelihood that employees will participate successfully in staged exercises and events and provide useful information regarding how an incident response team will perform during an emergency.

Another important aspect of company culture is working together as a team. It is possible that a person may become fatigued but cannot convey this due to a communications outage. It is also conceivable that during an emergency a person may be unwilling to ‘leave their post’ until the job is done, becoming fatigued in the process.

It is important to have backup resources and to limit time in any role during the emergency to minimise the chance of mistakes being made. The emergency plan is only as strong as the weakest link in the chain of command.

For all resources, including external resources, provision of backups should take into account leave, prolonged illness and the need to ensure replacement when employees leave the company.

Where a company has a strong and positive safety culture and team ethos, detailed knowledge of its assets, regular inspection and exercising of valves and gates, and a commitment to team-based emergency training, employees are more likely to overcome the challenges posed by outages of power and communications during emergency conditions. They will find a way.

No one can predict and plan for every emergency scenario, but we believe that the tips we’ve shared here can help dam owners to develop and maintain robust emergency plans that have a higher likelihood of success when called into action.

If you would like support with your emergency planning, contact Richard Herweynen or Phillip Ellerton.

About the author

Jamie Cowan is a senior dams engineer at Entura with over 2 decades of civil engineering experience in the UK and Australia. His experience includes the management of investigation, design and construction projects in the civil, dams and water industries. He has worked across all stages of project delivery, from feasibility to the commissioning of assets. He has provided construction support roles during dam construction and upgrade projects, and conducted intermediate and comprehensive inspections of dams for water authorities in Victoria.

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Dam Emergency Dewatering Outlets: A ‘Must Have’, or a ‘Nice to Have’?

One contributing factor for dam safety is the ability to rapidly lower the water level in an emergency. But how can dam designers and owners appropriately determine the need for a dewatering outlet or its optimum size in the absence of a consistent international standard? 

Above: opening of a low level dam outlet in South Africa

Dam safety must begin long before the dam is filled

Dam owners are responsible for the continued safety of dams throughout their life cycle, and for maintaining acceptable levels of risk exposure for downstream communities. As we’ve highlighted in previous articles, dam safety can protect lives and drive efficiencies, having a robust approach to dam safety management must be a top priority for dam owners, regardless of the size of the dam.

A dam safety program should be underway before a dam is filled for the first time, especially if there is significant downstream consequences. This dam safety program should include details such as operational instrumentation, regular routine inspections, and personnel and systems in place to make the necessary decisions should any unusual observations occur. The dam safety manager is a key role required to escalate and make decisions in relation to this. In addition, the key dam safety documentation should have been prepared, including a dam safety management plan, dam surveillance plan, dam operation and maintenance plan, dam safety emergency plan, and evacuation plan. We’ve talked about these elements previously in our ten-point plan for safer dams.

Triggers for dewatering

During unusual events such as the first filling of the dam, major floods or major seismic events, the dam needs heightened scrutiny. If visual inspections and instrumentation monitoring indicate any sudden increase in dam deformation, leakage or internal pressures, it is important that an incident is raised and investigated. If the change progresses and may be developing into a dam safety incident, the risk mitigation strategy may be to reduce the reservoir level (i.e. the water loading on the dam).

To rapidly reduce the reservoir level, a low-level, emergency dewatering outlet is usually needed.

The need for an emergency dewatering outlet

It is good practice to provide an emergency drawdown facility in a dam. This enables the reservoir level to be reduced in a dam safety emergency, which lessens the loading on the dam and the volume of water behind the dam.

The purposes of an appropriately sized low-level outlet are (1) evacuation of the reservoir if emergency conditions occur, or inspection, maintenance and repair of the dam and appurtenant works that are normally submerged, and (2) controlling the rate of reservoir rise as required by reservoir filling criteria.

There are examples in Australia and internationally in which no emergency dewatering outlets are incorporated into the dam, or the total outflow capacity provided is inadequate. Yet there is no consistently adopted international standard for the requirement and sizing of an emergency dewatering outlet. This gap in consistent guidance is of concern, given the importance of dewatering outlets for dam safety.

Lack of consistent international standards for dewatering outlets 

The International Commission on Large Dams (ICOLD) provides no reference to a specific drawdown rate; however, a number of its technical bulletins do refer to a bottom outlet to empty a reservoir.

ICOLD Bulletin 49a – Operation of Hydraulic Structures of Dams (1986) states: “It is very important for the dam operator to have outlets enabling the reservoir to be drawn down. While bottom outlets do not readily fit into some sites (as with very large reservoirs on very large rivers), there are still many cases where their absence is regrettable or where they are too small or ill designed … Besides allowing the reservoir to be emptied in periods of low river flow, bottom outlets can also provide fine control of the reservoir during the most critical period of a dam’s life, during the first filling, and draw down the level whenever necessary thereafter.”

Some guidance for emergency drawdown was given by the United States Bureau of Reclamation (USBR) in 1990, suggesting drawing down the reservoir volume to either 10% of the storage or 50% of the height in 1 to 4 months. 

However, as these guidelines suggest, it may be impractical to provide the drawdown capability to meet the criteria and guidelines for certain projects. Some reservoirs may be just too large for short-term evacuation. The USBR guideline recognises that decisions relating to emergency dewatering outlets should be made considering the risks that the outlet would help to mitigate and the costs to include such an outlet.

Promoting a risk-based framework 

A more recent guideline on emergency dewatering outlets for dams is the UK Environmental Agency’s Guide to Drawdown Capacity for Reservoir Safety and Emergency Planning (2017). This document provides guidance on a consistent methodology for assessing the adequacy of existing drawdown capacity at reservoirs in the UK, based on the judgement of an experienced dam engineer. This judgement should consider the proposed basic minimum recommended standards, the consequence of dam failure, the vulnerability of the dam to rapid failure, the time it may take to detect symptoms of failure and to activate drawdown, the time required to draw down the upper third of the reservoir, the ability to keep the reservoir down for repairs, and precedent practices.

The guidelines promote a risk-based assessment, considering options for mitigating those risks. The guidance document states: “The cost of increasing drawdown capacity is compared to the reduction in risk to life achieved, and only implemented where the cost is proportionate”.

These UK guidelines therefore encourage a risk-based framework for evaluating the drawdown capacity of any emergency dewatering outlet. However, the UK has very few very large reservoirs on large catchments, and the guidance provided may therefore not be applicable to very large reservoirs.

What about larger reservoirs?

The challenge in applying the existing international guidance is when the reservoir is very large and/or the dam is located on a very large river. These larger reservoirs are often associated with hydropower projects. This is recognised in the guidance documents discussed above; however, an alternative approach is not provided.

Both the UK and USBR documents do suggest, though, that the reduction in risk created by an emergency dewatering outlet should be weighed against the cost.

Given that an emergency dewatering outlet is not always possible or practical (particularly for large reservoirs), how can risks be mitigated in other ways?

Seven considerations for safer dewatering decisions 

When determining whether a dewatering outlet is a ‘nice to have’ or a ‘must have’, systematically consider the alternatives through a risk-based framework and document the decision. With or without an emergency dewatering outlet, it is crucial to develop a robust design, fully consider dam safety, and appropriately mitigate risks to acceptably low levels.

Click to enlarge

Think about these seven points:

1. Consider the inclusion of an emergency dewatering outlet early in planning and design.
   It is often easier to incorporate an emergency dewatering outlet into the dam’s general arrangement in the early stages of the design process, rather than later when the dam type has been locked in and all the various components (spillway, intake, diversion) have been located and defined. If it is easy to incorporate, it is good practice to include.

2. Consider the risk position without any emergency dewatering outlet.
   The main purpose of the emergency dewatering outlet is to be able to take some mitigating action in a dam safety emergency. It is therefore important to determine the risk position of the dam without an emergency dewatering outlet, and evaluate whether this risk is acceptable based on the downstream consequences. Every dam site is unique, so all potential failure modes for this particular dam need to be considered in the risk assessment. If the risk position is not acceptable, alternative options for mitigating the risk should be considered and built into the design and/or operational procedures. Adopt a robust design with sufficient redundancy to mitigate the risks identified through the potential failure modes analysis.

3. Understand the potential benefits of an emergency dewatering outlet.
   Before deciding that it is too costly to construct an emergency dewatering outlet, at least consider the potential benefits. Gain an understanding, from a holistic project perspective, of the hazards/risks that an emergency dewatering outlet could mitigate. Consider the importance of controlling the rate of initial filling of the reservoir, the ability to evacuate the water from the reservoir at a meaningful rate to make a difference in a dam safety emergency, and the ability and ease of repairing issues below reservoir level by lowering the reservoir rather than undertaking repairs underwater.

4. Assess the risk benefit of an emergency dewatering outlet against the cost.
   Carefully evaluate the reduction in risk due to the presence of an emergency dewatering outlet compared to the cost – is there a strong justification or not? Even if a full-capacity dewatering outlet is not possible, consider the risk benefit against cost for what is Compare the risk difference ‘value’ with the cost of the emergency dewatering outlet. This will inform a conversation about whether the ‘value’ justifies the cost, which is a strong basis for a sound decision.

5. Develop contingency plans for the future.
   If there is no emergency dewatering outlet that can enable the reservoir to be emptied for repair works, consider what repair actions may be required during the life of the dam. Ask the questions: What might go wrong? How would we rectify that if we cannot dewater the dam? and Is there anything else that we could build into the design to make this easier? This is ‘safety in design’ thinking, and documenting these high-level contingency plans in the operation and maintenance manual will help those managing the dam in the future.

6. Document and communicate the decision.
   Document the entire decision process and include the reasons for any decision. All key stakeholders should be aware of and accept the ramifications of any decision.  Your organisation should have a robust process in place to assist this decision making process and ensure appropriate consideration in relation to an emergency dewatering outlet.  The appropriate dam regulatory body will also need to support and accept the decision.

7. Have a robust dam safety program in place.
   Any dam with significant consequences downstream (as defined by ANCOLD Guidelines, or similar) should have an appropriate dam safety program in place. If an emergency dewatering outlet is not part of the facility, it is important that the other dam safety risk mitigation strategies identified in point 2 are implemented. The dam safety emergency plan should clearly state the actions to be undertaken in a dam safety emergency, as well as who is responsible for them.

A dam safety emergency dewatering outlet can enable a dam owner to be proactive in a dam safety emergency, and help to maintain or reduce the dam safety risk. As such, it is always a nice thing to have as part of a dam facility, and it should, ideally, be included in any new dam. However, if it is not possible or practical to include a dewatering outlet, be sure to make careful, considered decisions based on a comprehensive understanding of risks and consequences.

Above: Catagunya Dam dewatering outlet operating during functional testing in 2014

If you’d like to discuss how we can assist you with planning, designing and constructing safer dams, please contact Richard Herweynen, Paul Southcott or Phillip Ellerton.

About the author

Richard Herweynen is Entura’s Technical Director, Water. Richard has 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 is 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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What levels of flood protection and downstream risk are acceptable for cofferdams?

In previous thought leadership articles, we’ve argued that the downstream consequence of dam failure is a better measure of dam risk than the size of the dam. For example, saddle dams can often have significant consequences downstream, despite being smaller than the main dam. The same applies to cofferdams.

A cofferdam is a temporary dam that diverts a river during construction of the permanent dam. The cofferdam enables the main dam site to be dewatered and protected throughout construction. The river flows are diverted around the site through a diversion channel, conduit or tunnel, which has a certain flood capacity beyond which the cofferdam would overtop. Overtopping of the cofferdam could lead to failure of this temporary dam, and the ramifications of such an event depend on the volume of stored water behind the cofferdam and the consequences downstream.

There is greater scope to accept more risk in the design and construction of the cofferdam if the construction period is short, the cofferdam is relatively small and the downstream consequences are minimal. But if the cofferdam is a high structure with significant consequences downstream, what level of flood protection is acceptable?

This issue is common when constructing a dam on a large river. Despite the cofferdam usually being significantly smaller than the main dam, and although the risk exposure period is only the duration of the construction of the permanent dam, we must consider the life safety risk to the downstream community. If the downstream consequence is great, appropriate dam engineering principles and standards need to be applied to the design and construction of these temporary cofferdams to protect the downstream community from unacceptable risk during the construction of the main dam.

There is no consistent, appropriate international practice or standard for risks associated with handling flood during construction, be it for river diversion during construction of a new dam, or flood management during remedial works for an existing dam. The overall perception of dam engineers has been that higher risk levels are acceptable during short-term construction periods, compared with the long-term risks for the completed structure.

Traditionally, the flood capacity associated with the cofferdam and diversion works was based around the construction flood risk and became a cost optimisation problem, taking into account the lost time and damages that would be caused by overtopping. However, if there is a population downstream, we are talking about the downstream risk to life, which is no longer simply a financial issue.

The outdated Australian National Committee on Large Dams (ANCOLD) Guidelines on Design Floods for Dams 1986 proposed that the river diversion flood risk during the relatively short construction period of a cofferdam should be an equivalent order of safety to the recommended design flood relevant to the consequence over the life of the permanent dam. For a high-consequence-category dam with a construction period of 5 years, the guidelines recommended a 1-in-500-year river diversion flood capacity.

This is similar to the Brazilian guidelines given in the International Committee on Large Dams (ICOLD) Bulletin 170 – Flood Evaluation and Dam Safety (2018), where for each management stage of the river during construction, the flood capacity for the diversion works should be defined based on the risk of flooding downstream, taking into account the exposure time. The following table is based on the Brazilian guidelines, taking into account the risk to human lives downstream. If there is real danger of loss of human lives and there would be major damage to the works and their progress, then the annual risk of damage to the cofferdam should be less than 1%.

According to the ‘Diversion of Large Brazilian Rivers’ document prepared by the Brazilian Committee on Dams for the 2009 ICOLD Congress in Brasilia, the maximum river diversion flood capacity provided for major dam projects in Brazil was the 1-in-500-year flood. This is currently considered to be the internationally accepted standard for temporary cofferdams, but is it acceptable from the perspective of risk to life for downstream populations?

Owners need to consider the degree to which the risks imposed on the population by the dam during construction are acceptable and defensible. The current ANCOLD Guidelines on Selection of Acceptable Flood Capacity for Dams (2000) indicates that there is no consensus or risk standard that specifically considers whether risk-to-life criteria that relate to the overall risk over the long life of a dam are equally applicable to the short-term construction period. Compliance with various risk-to-life criteria would generally result in very conservative construction flood provisions compared with historical practice, and therefore should only be used to assist when considering and deciding on construction flood options. Although it may have been traditional to accept higher risks during construction than those acceptable for the completed dam in service, it is unlikely that such practice would be defensible in the event of a failure resulting in loss of life.

When deciding on the diversion flood capacity for the cofferdam arrangement, consider these elements:

1. Consider the downstream consequences of an upstream cofferdam failure. This is particularly important if there is a downstream population that would be at risk. To quantify the impact of dam failure, dambreak assessment may be needed for the upstream cofferdam.
2. Adopt an engineering standard for the cofferdam that reflects the risk. The higher the consequences downstream, the more stringent the design standards should be for the cofferdam, including the flood capacity of the diversion works. The design should consider the potential failure modes of the cofferdam (e.g. flood overtopping, internal erosion, etc.), and appropriate design measures should be adopted so that the chance of failure is appropriately low.
3. Explore ways to mitigate the risk to the downstream community by:
   1. giving preference to lower cofferdam options with larger diversion flood capacity
   2. staging the flood protection works to minimise exposure time
   3. including emergency spillways or fuse plugs as part of the cofferdam design to control any downstream flooding
   4. preparing for major flooding events (as discussed below).
4. Ensure that the cofferdam is constructed in accordance with the design and with a high level of quality assurance, especially if the cofferdam is demonstrated to be a high-consequence-category dam. The quality control (QC) and quality assurance (QA) processes on site must reflect the downstream consequences and risk to life. The higher the risk, the higher the justification for investing in appropriate QA/QC for the cofferdam construction.
5. Have a dam safety emergency plan (DSEP) in place during construction. If downstream populations are at risk, it would be appropriate to have a DSEP for the cofferdam during construction of the permanent dam, along with appropriate monitoring of the cofferdam. Having a DSEP in place during construction is good practice for any high-consequence dam. By monitoring the dam, it is possible to identify early whether a dam safety emergency is developing. Early identification allows appropriate action to be taken as soon as possible, through intervention or early warning. This will help to mitigate the residual risk for the downstream population, and enable the contractor to intervene at the construction site. It will also provide clear lines of communication and understanding of responsibilities, should any potential dam safety emergency occur.
6. Develop and implement good flood forecasting and warning systems. If a contractor has enough warning before the flood occurs, they can act to mitigate potential impacts. For example, construction workers and equipment can be removed from the area between the upstream and downstream cofferdams. Adequate warning time will dramatically increase the chance of survival should the dam fail. With appropriate rainfall stations and streamflow stations, flood prediction and flood warning models can be developed to provide increased foresight before a large flood event, so that there is more time to take pre-emptive action and inform any downstream communities.

Click on image to view full size.

No matter the size or the impermanence of a dam structure, always consider the downstream consequences. Even though a cofferdam is a temporary structure, it is still a dam, and its failure could lead to significant downstream consequences including risks to life. And that’s why we should consider applying the same dam safety practices to cofferdams as we do for permanent dams. In the end, it’s all about identifying and managing the risks and protecting what’s vulnerable downstream.

Find out what prompted Richard to write this piece below. 

Entura has been involved in the decision-making process for many cofferdams associated with the construction of large dams on large rivers. If you’d like to discuss how we can assist you with planning, designing and constructing safer dams, please contact Richard Herweynen, Paul Southcott or Phillip Ellerton.

About the author

Richard Herweynen is Entura’s Technical Director, Water. Richard has 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 is 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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Make better decisions about hydropower and dam project options using risk-based multi-criteria assessment

How can owners or developers assess alternative options for hydropower and dam projects objectively and consistently? How can you maintain an appropriate balance among the environmental, social, financial and technical risks? If you place a value on the non-cost aspects of projects, how can you confidently assess the many criteria that your project options bring into play? 

Traditional methods aren’t always best

The traditional approach to evaluating a range of alternative project arrangements and selecting a preferred option would be to apply a numerical ranking and weighting to a range of criteria to reach a weighted score for each project option (as shown in the table below). The recommended project arrangement would generally be the one with the highest weighted score. However, there are some major downsides to this methodology.

Click on image to view full size.

One problem with the traditional method is that the guideline for scoring can be fairly arbitrary (e.g. 1 = poor, 10 = excellent or 1 = high cost, 10 = low cost). Furthermore, scoring can be subjective and can vary from assessor to assessor. A project with strong scores in some areas may still achieve the highest weighted score even if it has low scores in other areas – and this can be accentuated by varying the weighting of individual criteria to contribute less to the overall score. Individual low scores can be very important as they could be show-stoppers. The averaging approach can therefore be misleading. The lack of transparency of this traditional approach can make it difficult to explain the results to internal and external stakeholders.

An alternative approach is a risk-based method.

A risk-based approach to multi-criteria analysis brings benefits

Compared with the traditional method, a risk-based approach may lead to a less subjective and more defensible assessment, as a consistent set of criteria is applied across all projects and/or arrangements. High risks remain very visible because there is no weighting or averaging. This process can be easily explained to internal and external stakeholders.

A risk-based approach uses a risk rating table, similar to that shown below, which can be used to rate the risks of many different types of hazards. This approach is familiar to many because it is used extensively throughout industry in many applications including, for example, safety management.

Click on image to view full size.

The standard risk assessment process is followed, which involves identifying the hazards, assessing the likelihood and consequence and therefore risk, identifying mitigation measures and re-evaluating.

Define the likelihood and consequences of risks

To undertake a multi-criteria assessment using a risk-based framework, you first need to develop a set of definitions for consequence and likelihood. The definitions should relate to a set of criteria, for example a hydropower project may consider natural environment, social and cultural heritage, reputation and client relationships, planning and approvals, and project delivery. For each criterion, define the consequence, ranging from a ‘Low’ through to a ‘Catastrophic’ outcome.

Developing these consequence definitions can be complex and require endorsement from within the owner’s or developer’s organisation. Many organisations already have a set of relevant consequence definitions as part of their corporate risk management processes. In some cases, these definitions may need amending (e.g. to accommodate a larger project); however, this could potentially be easier and more efficient than starting from scratch.

Developing a likelihood table is relatively straightforward. It simply requires a probability range to be associated with each likelihood definition, for example ‘Almost certain’ = 90–100%. The likelihood table can then be applied in subsequent risk assessments.

Once the consequence and likelihood definitions are agreed, you’re ready to undertake the multi-criteria assessment using a risk-based framework.

Nine steps towards a robust multi-criteria options assessment

Depending on the project, a multi-criteria assessment will often involve considering the cost, schedule and risk of each option.

The following checklist sets out a nine-step method to guide a risk-based multi-criteria assessment of alternative options for a hydropower, pumped hydro energy storage or dam project.

Click on image to view full size.

The steps set out above can be repeated to review other project options.

Ultimately, a degree of subjective evaluation may be needed, but this methodology will certainly support you to consider multiple criteria in your decision-making process, and is likely to highlight any major risks that may be considered to be show-stoppers. Using a risk-based approach and following the methodology above will set you on a solid path towards a consistent and defensible approach for your options assessment.

If you would like to discuss how Entura can assist with assessing your project options and their associated risks, including multi-criteria assessment of your hydropower, pumped hydro energy storage or dam project, please contact Phillip Ellerton on +61 439 010 172, Tim Griggs on +61 409 365 329 or Richard Herweynen on +61 429 705 127.

About the author

Tim Griggs is a specialist civil engineer with the hydropower and pumped hydro energy storage team at Entura. He has over 25 years of experience in the fields of civil engineering, dams and hydropower including feasibility studies, design and construction support, and has worked on projects located in Australia and the Indo-Pacific region. He is currently the hydropower design leader for Hydro Tasmania’s Battery of the Nation project that is undertaking feasibility studies into the development of a large pumped hydro energy storage project in Tasmania.

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Multipurpose dams: maximum value for money?

When a dam is being considered, there’s usually a primary purpose. But are there also secondary purposes that can benefit the local and wider community? Have you thought about the potential additional economic development that can stem from a multipurpose dam? 

A simulation of Alaoa Dam in Samoa

Multipurpose dams combine two or more functions of traditional single-purpose dams into one dam infrastructure project. A multipurpose dam may combine storing and supplying water for irrigation, industry or human consumption; flood control; power generation and power storage; navigation; water regulation; environmental releases; climate change resilience; and recreational purposes.

The dam structure will be similar to a single-purpose dam, but the design will incorporate features into the dam and water infrastructure facility to accommodate different purposes. These may take the form of irrigation channels, power generation facilities or navigation facilities. Including various gates or valves can provide greater operational flexibility for floods or environmental releases for downstream community and environmental needs. A single-purpose project can become multipurpose during its planning stage, during operation, or in the long term when re-engineering becomes necessary.

Why consider multiple purposes?

Multipurpose dams are not a new concept; in fact, almost half of all dams are used for more than one purpose. There is a growing trend to consider multiple purposes when developing a dam, for several reasons:

1. Dam sites, particularly storage sites, are scarce national resources (i.e. they are not unlimited), so it makes sense to consider how to extract maximum benefit from them when constructed.
2. Dam infrastructure may commonly last for up to 100 years or more (i.e. they are considered a long-term asset). A dam represents a genuine long-term investment for the future, and so ideally should be viewed as such and incorporate the potential for flexible use over time.
3. Multipurpose dams are very beneficial in developing countries, as the multi-functionality of the dam operations can contribute to a number of development goals simultaneously, such as energy, water and food security, economic development, and climate resilience. In 2016, the International Commission of Large Dams (ICOLD) recognised the importance of multipurpose dams in the release of the ICOLD Bulletin ‘Multipurpose Water Storage – Essential Elements and Emerging Trends’, which rightly links the common global needs of water, food and energy. The sporadic, spatial and temporal distribution of precipitation rarely coincides with demand, making storage essential for food supply, energy production, potable water supply and other water delivery services that depend on sizable, reliable, continuous and efficient supply of water.
4. Climate change scenarios predict increasing variability in rainfall, impacting both yields and flood peaks. Droughts will affect agricultural production, and flooding is expected to increase due to more extreme weather events. With many regions of the world experiencing significant water stress, which is expected to be exacerbated by global warming, storage will play an increasingly critical role in bolstering a water system’s hydrological resilience. Dam projects should be designed with this necessity and value of storage in mind. Even in developed countries, we need our dam infrastructure to be ready to adapt to future changes as required. Taking change into account and considering multipurpose approaches will benefit new dam projects as well as projects that modify existing reservoirs.

Click image to view infographic.

Looking into the future

Multipurpose water storage projects pose additional engineering challenges when compared to single-purpose projects. Given the longevity of the infrastructure of large storage projects, planning professionals need to develop and implement solutions that will provide adequate flexibility to adapt to changes or to the diverse needs of multipurpose schemes. Scale, site selection and operational characteristics should be assessed through a long-term perspective, incorporating anticipated trends and emphasising adaptability so that future generations will inherit infrastructure that can evolve as the world continues to change.

There is no doubt that this sustainability principle is valid; however, determining how best to implement it in practice is not always easy. It is hard to anticipate and predict what will happen in a century (which is the expected life of many dams), yet this should not stop us during the early stages of the project from trying to assess long-term performance based on potential long-term scenarios (i.e. scenario testing).

Multiple perspectives for multiple purposes

Achieving the best outcome for a multipurpose dam is more likely when planners and engineers work together and closely consider the local community’s needs and the potential benefits to be gained. Both social and environmental needs should be considered, with detailed social and environmental impact assessments conducted.

Applying the principles of Integrated Water Resource Management (IWRM) in the planning process will help promote coordinated development and optimal management of water resources – furthering progress towards goals of social equity, economic efficiency and environmental sustainability. It is important to establish criteria by which to monitor the achievement of the multipurpose objectives and the post-construction impacts on the community and environment. Another important consideration is the manner of operation of the multipurpose reservoir, which will also be critical to achieving the range of its objectives.

What is a multipurpose dam worth? 

A key planning challenge in multipurpose dam infrastructure is fully appraising the economic costs and benefits of the project. In many projects there’s a tendency to focus the analysis on the components that provide revenue streams (such as energy and water supply and irrigation tariffs) as these are most easily valued. However, this can underrepresent the project’s value across all of its multipurpose objectives, potentially resulting in suboptimal decision making or difficulty justifying the long-term investment. For example, a fundamental purpose of storage projects is flood mitigation – but flood mitigation does not generate a revenue stream. However, the economic value of flood control to a country (through avoidance of direct and indirect flood damages) often justifies the allocation of funds from the public sector.

Putting this into practice in Samoa 

The Alaoa Multi-Purpose Dam in Samoa is a fitting example of the considerations presented above.

Samoa is a small tropical island country in the Pacific, and has been heavily affected by severe tropical storms. In 2012, Cyclone Evan caused extensive flooding and damage to the Apia region, the capital, where most of the population and economic activity is located. With such storms predicted to increase in frequency and severity as the climate changes, the Government of Samoa has adopted a programmatic approach to address climate-change-induced flooding. This includes the new Alaoa Multi-Purpose Dam, sized and designed with long-term climate scenarios in mind and to provide multiple functions. It aims to increase flood protection, improve the current water supply system’s seasonal reliability, and provide additional hydropower via installation of a small hydro facility.

The dam’s design considered multipurpose functions and climate change risks, and included small modifications to provide better outcomes. Climate resilience was ‘designed in’ by incorporating ‘dead storage’, providing sediment flushing capability, increasing the flood capacity, and including a number of gates and valves – all contributing to future flexibility of operation.

The intake to the small hydro station incorporated a station bypass valve for water supply. As well, a low-level outlet and a mid-level outlet were added to increase the operational flexibility of the dam to meet its three purposes. This also enabled both low-flow and high-flow environmental releases, and improved dam safety management. How the reservoir is operated will be significant in achieving the multipurpose functions. The dam’s flexibility will allow future adaptive modification of the operation to align with the changing demands of the reservoir.

The main purpose of the Alaoa Multi-Purpose Dam was flood retention and mitigation. Consequently, as we discussed above, a limited financial analysis could not justify the multipurpose project, yet the broader economic analysis could. However, the financial analysis indicated that the regular revenue stream from the small hydro’s energy production could increase the project’s sustainability once constructed. This revenue stream would contribute to the ongoing operation, maintenance and dam safety activities associated with the multipurpose project’s long-term operation.

Could multiple purposes be incorporated into your dam project? 

Whether you are in the planning process or the early design phase for a new dam, consider whether your project could be modified to:

• achieve multiple purposes and increase the benefits of your dam project
• increase operational flexibility to allow your dam to adapt to future changes and demands
• improve the use of water resources for all needs, including the environment
• increase the climate resilience of your dam and the impact of climate change on its multiple objectives.

If you would like to discuss how we can assist you with planning and designing a multipurpose dam, please contact  Richard Herweynen, Paul Southcott or Phillip Ellerton.

About the author

Richard Herweynen is Entura’s Technical Director, Water. Richard has 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 is 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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Keeping international projects moving, even when we’re grounded

With no set date for when life will return to usual after COVID-19, nor any guarantee of whether life will ever return to what we previously knew as ‘usual’ at all, there are very few areas in the consulting life in which we can simply say ‘we’ll wait until this is all over’. Life, and projects, must go on.

Although we can’t avoid the disruption and uncertainty that the coronavirus has unleashed, we can increase our resilience and agility. We can also embrace opportunities to innovate and to create new ways (or reinvigorate old ways) to achieve our goals.

Here, Entura’s Environment and Planning team continue to apply their proactive approach to keeping projects alive in the current circumstances, and explain how they are continuing their activities on two international projects despite the travel restrictions that are making it impossible to visit the project sites.

Old ways for new times – Engaging communities in Tonga

For many countries across the globe, the immediate challenge is building resilience to fight through the pandemic. However, for some small island nations that have managed to stay out of the virus’s path so far, such as Tonga and the Federated States of Micronesia, the concept of resilience has a broader context.

Climate resilience is a core objective, as these nations are feeling the increasing impacts of rising sea levels and more frequent and intense weather events. In this context, robust power infrastructure that is suited to extreme weather is one component of greater resilience, as is transitioning from diesel dependence to higher levels of renewables, which builds greater security of energy supply at a lower longer term financial and environmental cost. More access to stable, reliable and clean electricity is also critical for the health, wellbeing and education of local communities, and is the foundation for economic development. Entura has been fortunate to be involved in some meaningful resilience-building projects in the Pacific, supporting many of our neighbouring nations to implement sustainable energy solutions.

However, with a current project in Tonga, coronavirus has thrown our travel plans into disarray. The challenge we’re facing now is how to continue the planning, engagement and environmental activities required by such a project when we can’t physically get there, can’t hold town hall meetings and can’t host information sessions with locals.

While the pandemic is forcing many practitioners to extend and expand their use of digital forms of engagement (such as websites, Facebook, Twitter, ‘Bang the Table’ or moderated ZOOM-based focus groups), some projects are located in communities that do not enjoy easily available or reliable internet or telephone access. In these cases, such as our project in Tonga, we need to think differently about ways to facilitate engagement from a distance.

For the Tongan project, we’re heading back to basics: the tried and tested solution of providing information on paper. Working with the local project management unit, along with our client, we are designing and implementing a newsletter to be printed in the local language and distributed to regulators and communities. It will provide snapshots of the project, latest updates on scheduling, and will even feature some interviews to provide greater coverage of ongoing community engagement.

As the construction company for the project is, like us, unable to travel internationally at the moment, construction is yet to take place. Nevertheless, we are continuing to facilitate all aspects of the project remotely, such as lining up approvals with regulators, and guiding engagement on the ground. With the help of our Tongan counterparts, we can still keep information and updates flowing despite the physical limitations on our involvement ‘in the flesh’.

Buying time and building partnerships in South-East Asia

Just as COVID-19 started closing borders and halting international travel, our team was reaching the culmination of many weeks planning an impact assessment for a large infrastructure project in South-East Asia. Our discipline experts were about to book their tickets and embark on the journey to site to survey environmental and social impacts. However, we placed the site surveys on hold indefinitely to comply with travel restrictions, ensure the safety of our people and contractors, and not risk spreading the virus in remote communities.

This abrupt shift in our plans afforded us the chance to take a breath, reflect on the project and its broader risks, and then develop an alternative plan to keep progressing aspects of the work that could be done remotely. We are now proactively undertaking desktop approval studies and initial public consultation from our desks. We’re ‘buying time’ now to save time later.

When travel restrictions lift and it is once again safe to physically attend the site, we will be ahead of where we would have been pre-COVID-19. We will better understand potential issues and have a more thorough insight into the local and community context. We’ll have already carefully planned our field studies with more targeted approaches. We’ll be better prepared for stakeholder questions that may arise, and will have already considered ways in which the project might manage challenges and risks going forward.

But there’s something more that we’re seeing emerge in this COVID-19 period. We’re finding that the shared need to adapt to trying times and the mutual desire to find workable solutions is strengthening our relationships with our clients, building even greater trust and collaboration, and it is leading to ‘partnership’ relationships that transcend the more common transactional paradigm of client–consultant. We are working closely together to openly discuss issues and options, and to determine how best to manage emerging challenges to benefit the project.

Would this have happened without COVID-19? Perhaps – but under the usual pressure of timelines, expectations, standardised processes and the drive for efficiency, there isn’t often the same flexibility or space to build different qualities and layers in our relationships or to consider potential issues quite so broadly or creatively.

Will the project benefit from the changes made necessary by COVID-19? Probably – despite the difficulties caused by the limitations on travel, it can only be positive to have had the chance to take the time to more thoroughly and holistically consider all the issues and risks before we proceed to field studies and stakeholder engagement.

Will timelines change significantly because of COVID-19? Not necessarily – we will inevitably lose some months by not being able to go into the field, but we will have ‘bought’ some time by compiling a good portion of the project documentation prior to the field studies, so that the time required in subsequent stages is lessened.

Wherever in the Indo-Pacific region our international projects are located, our clients can be confident that we’re seeking all the ways we can – new or old – to keep making progress in these uncertain and complicated times … and to come through them stronger together.

If you would like to discuss how Entura can help you with your environmental or planning project, please contact us.

Don’t let COVID-19 stop your project

A vital part of the success of all projects, whether they are new or operational, is maintaining progress towards milestones and retaining currency in the social and regulatory realms. How can we achieve this during a global pandemic?

With the COVID-19 crisis affecting people and businesses across the globe, employers and employees alike are racing to find normalcy. Fortunately for Entura, we’ve already been working and collaborating virtually for many years across country and state borders, with dispersed office, client and project locations. So, even though our teams are working from home, it is still business as (mostly) usual, in unusual times!

Although COVID-19 hasn’t thrown us completely, travel restrictions have pushed us to think differently about many of our projects and methods. This is the time to explore proactive ways to ensure projects do not come to a grinding halt or fall off a community’s or regulator’s radar.

Keeping environmental and planning projects moving forward

Entura’s environment and planning team works frequently in the field – lakes, forests, roadsides, development sites and many more – so COVID-19 travel restriction have taken a hit at our ability to undertake survey and monitoring programs or to conduct site visits, but it hasn’t led to tools down.

We may miss out on our chance to hit the frosty outdoors this autumn and winter, but there are still many ways that we can and will continue to make progress and deliver value. It’s about thinking creatively about how we can be proactive. And that means finding measures and activities for the short and medium term that will keep the project moving towards the longer term project milestones and goals (without the anticipated longer term extending into the much further horizon!)

For example, there are proactive things we can do to prepare us better for when we can once again visit the site. We have access to a wide range of data and can undertake thorough desktop investigations early in the project. We will then be able to step on site well prepared and looking to fill knowledge gaps or to verify what should be there. That puts us in a better position to be alert to anything unexpected we might find when we’re physically on site in future. Unusual discoveries and observations will be more pronounced. Such approaches can help shorten project timelines post-COVID-19 compared with the inevitable blowouts that would be caused by downing tools completely.

Policy and regulatory reforms are also still happening across the country – some as a result of COVID-19, others associated with larger reform programs to update antiquated legislation. Our discipline experts continue to engage with the regulators and relevant government agencies and authorities to ensure we understand the nuances of these changes and how they may influence the scope of existing and future projects and programs of work.

More proactive, less reactive

The restrictions caused by COVID-19 have highlighted the need to be proactive so that we can be better positioned for the longer term. It’s natural for a consulting paradigm to tend towards the reactive and process-driven, but this is the time to shift such tendencies.

With a future-focus and forward thinking, we can all seek out proactive solutions to keep projects and processes running as smoothly as possible, to meet any milestones that are still feasible, and to do everything that is reasonably possible in the present circumstances that will minimise delays once the pandemic has eased.

This needs to be a shared process. If as consultants and clients we put our heads together, we can develop shared understandings of the opportunities, risks and issues affecting all parts of the project and all the players involved. With team work and good communication, together we’ll find the most innovative and workable solutions, and together we will survive and thrive.

Beyond the immediate

The circumstances of the pandemic are also an opportunity to think beyond the immediate projects on our desks. This is a great time for our clients to review their projects and environmental and social management practices, to be better positioned for the post-COVID-19 future. This could include being more informed about potential risks or thinking through changes that you could make to your management practices to better address ongoing or emerging issues.

In our next article, we will highlight some of the projects we are currently working on, and how we have adapted them in light of COVID-19. We will also dig down into some of the key regulatory reforms happening across the country, and what implications they may have on projects during the COVID-19 period and beyond.

At Entura, we will continue to respond to government measures as they surface, and we will continue to be here to assist all our clients to better understand the opportunities, risks and issues associated with keeping your project alive during COVID-19.

A message from our team to yours

And to finish on a light note – Entura’s environment and planning team has nimbly settled into their new branch offices, from urban Melbournian set-ups to peri-urban workplaces at the foothills of the majestic kunanyi/Mount Wellington in Tasmania. From our team to you or yours, here are a few handy tips which we have found to help with this transition to working from home:

• Stay connected – drop your colleague or manager a line and ask how they are going, and where possible (bandwidth permitting), turn on the video during your virtual meetings.
• Schedule regular team catch-ups, and why not end the week with an optional virtual gathering to kickstart some weekend banter?
• Don’t be embarrassed if your pets or children make an appearance – it helps lighten the mood and may provide the laugh that someone really needed.
• Get some fresh air before you start work – imitate that commute to work by going for a walk or cycle.

If you would like to discuss how Entura can help you with your environmental or planning project, please contact us.

Pictured, clockwise from top left:

• Senior Social and Stakeholder Consultant, Dr John Cook
• Land Use Planner, Bunfu Yu
• Senior Aquatic Scientist, Dr Malcolm McCausland (and friends)
• Team Leader Environment and Planning, Raymond Brereton
• Senior Environmental Planner, Cameron Amos
• Senior Planning and Environmental Consultant, Scott Rowell (about to head out for a ride)
• Environmental Consultant, Rachael Wheeler

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Engineering – by humans, for humans

When engineers think about the future, do we get so engrossed in the complex technical problems that we don’t attend enough to the human angle?

Engineers have a reputation, whether rightly or wrongly, for being poor communicators, working obsessively and in isolation, and focusing on the immediate goal rather than its impacts on communities. Often, clichés have a basis in truth. If we are going to shift perceptions, we need to start by thinking about the way we work and the leadership we show to the next generation of engineers.

There’s no way we can predict the major developments, challenges or solutions of the next five or six generations of engineering careers. What we should focus on is what we can do right now to lead change in our profession and our communities – and I think the keys are communication, collaboration and community.

Communication

I recently listened to a podcast in which two energy market experts talked with a power system engineer. They discussed all sorts of technical matters relating to frequency and voltage control. I love those topics, but this conversation was limited and uninspiring because the participants simply didn’t have a common language or understanding.

We need to learn to communicate in ways that a variety of people can understand. That will mean better conversations with the people who can help our work have greater impact, and it will help our communities to appreciate the importance of our work in their lives.

It’s too easy for us as a profession to sit at our desks or stand under our hard hats and luxuriate in how clever we are, and then bemoan how so many people have no idea what we do and don’t value our work.

When things that involve engineers go wrong, a flurry of opinions erupts. Failures such as the blackout in South Australia, or the cladding issues at the Grenfell Towers, or issues with airlines or bridges or dams all lead to our communities questioning and debating engineering practice. Engineers tend to try to stay out of this rough and tumble for fear of being misrepresented. Yet maybe it’s better that we do engage where we can, since being misrepresented on a small issue is better than allowing a groundswell of misguided public opinion due to a lack of understanding of engineering principles. 

We need to try to better explain our work and find simple ways to convey the complexities of the decisions that we make. 

Collaboration

The world is far more complex now than it was a century ago – but it is impossible to imagine what level and pace of change future generations will experience. If we want to transform our world or help build a better future, we can’t do it by ourselves. 

Engineering no longer operates in isolation, if it ever did. We must collaborate across the engineering team and across other professional disciplines to achieve truly effective development for our communities. Sometimes we may need to focus a little less on technical delivery as a primary outcome, and increase our recognition of the value gained by engaging successfully with the communities on whom the project relies for success.

Collaboration makes our work more effective, and exposes us to a wider range of inputs and values that we can incorporate into our designs and processes. Engineering can be a leader but it can also be a facilitator for better outcomes when we draw on, listen to and learn from the other experts involved in other aspects of our projects.

Community

Engineering work almost always benefits more people than merely the one who pays the bill. Much of my work is in connecting wind farms and solar farms to the grid. Mostly my work is paid for by the owner of the farm, and while it delivers direct benefits to the owner through return on investment, it also affects everyone connected to the nearby network. It affects the network service provider and market operator, it pays salaries, and it supplies the clean energy that helps the country reduce emissions and meet its international targets. In other words, my work, which may seem intangible, has tangible effects in the real world.

If we agree that our labours produce real impacts, we need to take better care to fully consider the wider consequences of our work, which often has the potential to cause ‘collateral damage’. We can’t build a road or a wind farm without changing the landscape. When we build a machine, it uses energy and may emit pollutants; and it reduces reliance on manual labour, which may put someone out of a job. There may be a risk to lives, livelihoods or the environment if something goes wrong.

Do we always make decisions about these matters with the community front of mind, or do we place our clients on the higher pedestal? This is a tricky area and I’m not espousing a puritanical approach. However, if we knew in 1919 what we know now about lead poisoning, acid rain, greenhouse gases, scarcity and general sustainability principles, what different choices could have been made?

In a time of automation, we need to think about benefits and risks and how they affect our communities. On one occasion early in my career, I designed a controller to turn on and off a couple of compressors at a power station. I wrote some code to balance the run hours. A few months after the new system was commissioned, I asked one of the operators how the system was going, in terms of the run hours management, and he said ‘you’ve done me out of a job’. I hope he was joking. The task he’d been doing wasn’t particularly important, but there was value in having a person who was in tune with the equipment to take care of it, and there was also value in giving that person dignity through work.

My point is that we must keep our communities foremost in our minds as we go about our work. It’s not just about what we produce. It is the way we work and the people we choose to work with and for. Our influence on the development of the next generation of engineers perhaps has more impact on communities than our actual work outputs.

Through communication, collaboration and community, engineering can be both ‘more human’ and ‘for humans’.

About the author

Donald Vaughan is Entura’s Technical Director, Power. He has more than 25 years of experience providing advice on regulatory and technical requirements for generators, substations and transmission systems. Donald specialises in the performance of power systems. His experience with generating units, governors and excitation systems provides a helpful perspective on how the physical electrical network behaves and how it can support the transition to a high renewables environment.

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