Damming rivers is an old practice, and there are currently thousands of dams on rivers all over the world. These range from small projects that are spearheaded by local communities, to large modern constructions that hold back whole rivers, like the Three Gorges Dam in China. It doesn't look like this practice is going to stop any time soon. In the Amazon basin alone there are more than 400 proposed dam projects; spread across Brazil, Peru, Ecuador, and Bolivia.
It's easy to see why dams are popular. For a start, they are an important source of renewable energy and, unlike wind or solar generators, can provide a stable and reliable source of power. They can also help to regulate water levels to prevent floods and feed into irrigation systems that support large areas of farm land. These multiple uses mean that projects can potentially benefit a whole range of people, but these positives must be weighed against serious downsides. These negatives are rarely shared fairly.
The people who live near proposed dam sites are the most severely affected by new projects. When areas disappear under newly created reservoirs, whole communities, some of whom have lived in the area for generations, are forced to abandon their homes forever. These people often come from the poorest sections of society, so displacement simply piles further pressure on families who are already struggling.
In the case of the Amazon basin many tribal communities are being forced to leave their ancestral homes. This has caused a range of psychological and economic problems, and there are serious concerns about how these issues are being handled. However, it's not just those the people who lose their homes who are concerned about the impact of new dams.
Communities downstream often depend on the water for their livelihoods, so any change in the flow of a river can cause serious harm. This doesn't just affect people in the same country. As projects grow in size, the impact they have can cross international borders. This seems to be the case with proposed projects to dam large sections of the Mekong delta - primarily in China and Laos – and the effect it could have on Cambodian fish populations.
Fish is a major source of nutrition and income for Cambodians, so reduced fish supply is a serious problem. Equally, the loss of ancestral land has wide-ranging implications for Amazonian tribes. However, most of the beneficiaries of these projects – at the national and international level – do not directly suffer these consequences. This shouldn't mean that they can be ignored.
Settling the debt
The consistent problem for dam projects is that the negative impacts are highly localised, whilst the benefits are widely dispersed. Almost all infrastructure initiatives have to deal with this issue, whether it is a new high speed train line or an onshore wind farm, but in the case of dams it is particularly severe. How these challenges are dealt with can have major implications both for the specific projects and for the countries more generally.
To overcome this challenge projects' plans must include both the direct expenses and the wider costs to affected groups. This will mean involving all stakeholders in the planning process from the very start, in order to develop a clear and agreed means of measuring impact it will have. By recognising both the financial and social costs of a plan, decision makers can effectively assess the viability of the proposal.
Assessing projects in this way will also enable planners to take measures to limit the impact on those who are bearing the biggest personal cost. In the case of dams this would include minimising displacement as much as possible, compensating downstream communities, and providing support to help affected groups adjust to the changes.
The potential benefits that dams bring can be huge, but the only way these are going to be fully realised is to make sure the costs are also equally shared. Governments and companies must work hard to make sure this is the case.
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