THOUGHT LEADERSHIP

‘No dams’ or ‘right dams’? – that is the question

The construction of large dams may be controversial, particularly if the social and environmental impacts appear to outweigh the benefits. How can we create the right kind of dams in the right places to deliver maximum benefit with minimal impact?

I recently watched Franklin, a documentary in which eighth-generation Tasmanian and environmentalist Oliver Cassidy retraces his late father’s 14-day expedition to attend the Franklin River blockade in Tasmania in the early 1980s. The blockade aimed to stop the damming of the ‘Gordon below Franklin’. This was a divisive time, when many cars on the roads displayed a ‘No Dams’ sticker.

Indeed, some rivers have such high environmental and cultural heritage value that they should not be developed. However, given that water storage is a critical global issue, especially in a changing climate, is ‘No Dams’ a realistic stance?

Dams play an important role within communities by providing much-needed storage for water supply, irrigation and power generation. With greater hydrological variability due to climate change, more water storage will be vital to provide the same level of security for water, food and energy. The security of water, food and energy are inextricably linked, and all three are critical. For example, approximately 50 per cent of all large dams are used for irrigation. Without sufficient water storage, irrigated agriculture, which supplies 40 per cent of the world’s food, is at the mercy of changing patterns of rainfall and runoff. In our view, more water storage is needed for a sustainable future.

However, there are good dam sites and there are bad dam sites. In 2003, the World Bank, through its Latin America and Caribbean region, prepared a sustainable development working paper. This paper, titled Good Dams and Bad Dams, recognised that not all large dams are alike, particularly in terms of environmental and social impacts. It concluded that the level of environmental impact is largely determined by siting. It argued that while dams at good sites may be defensible, dams proposed at inappropriate sites are likely to remain problematic, even with proper implementation of all feasible mitigation measures, and are best left undammed.

Deciding on a site is not simple, and that is because sustainability challenges are complex. To help with decision-making about dams, the World Bank prepared environmental criteria for selecting sites for hydroelectric projects, building on its earlier work towards greater sustainability of dams throughout the 1980s and 1990s. In addition, the World Commission on Dams had been born out of a meeting in 1997 jointly sponsored by the World Bank and the World Conservation Union, and released its framework for dam decision-making in 2000.

International good practice has continued to evolve – and some principles are encapsulated in the Hydropower Sustainability Standard and assurance framework governed by the Hydropower Sustainability Council (drawing on the International Hydropower Association’s own tools and other sustainability principles) and underpinned by the San José Declaration on Sustainable Hydropower. Although these frameworks were created for the hydropower industry, they can be applied to any dam project.

So now, guided by these sustainability frameworks and motivated by the urgency of the clean energy transition and the multiple benefits of dams and hydropower, the challenge is to find the ‘good’, least-impactful dam sites, to enable more water storages to be developed sustainably. The need for more storage is particularly pressing in many developing countries – where there are critical needs for electrification, drinking water and flood mitigation, and where numerous and varied dam sites are available.

How do we do this? Clearly, site selection cannot simply be about cost-effectiveness alone, given that so much of what we value in life cannot be measured in dollars. At the recent Australian National Committee on Large Dams (ANCOLD) Conference, one of the keynote addresses was delivered by Gigi Foster. As an economist, she argued the importance of choosing the right ‘currency’ when making key decisions for society. She argued that we should judge a society by the extent to which it enables people to experience lives that are both long and of quality and wellbeing. A term used for wellbeing over one year is a ‘wellbeing year’ or WELLBY. Ideally, we should seek to maximise the number of future WELLBYs for people in the present generation, but also for future generations.

Arguably, the best dam sites may be those that maximise future WELLBYs – but this might be difficult to calculate. They may also be the dam sites which are the best based on a multicriteria assessment in which environmental and social risks are fully considered. There will be some potential dam sites where the environmental or social impacts are too great, and a dam cannot be justified. Good site selection is the most effective environmental mitigation measure.

Given that we need more water storage, we can:

1. Explore opportunities to increase the storage capacity of existing reservoirs by raising dams or by improving interconnection between storages to enable them to work together in a flexible and effective manner. Often, this can be more cost-effective and have lower environmental impacts than a new dam project. Where the benefits are high and the impacts are low, the WELLBYs are likely to be high.
2. Identify dam sites, either on-stream or off-stream, that will minimise environmental and social impacts. The simple quantitative indicators proposed in the 2003 World Bank Good Dams and Bad Dams paper could be used for an early preliminary rating and ranking of potential dam projects in terms of their possible adverse environmental or social impacts until more information is generated through detailed environmental and social impact assessments. The environmental and social considerations must be given appropriate weighting in the site selection multicriteria assessment, along with the financial, technical and other criteria typically included. If the assessment is well balanced, it is more likely to reach a positive outcome.

After many decades of controversy about dam development, and with increasing understanding of impacts and far greater sophistication of internally 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.

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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12 December, 2022