2015-2016 research highlights

I feel like I’m losing the river, the place we used to live, catch fish and food. Once we have moved away, my grandparents will lie deep under water.

This is how Deng Kai, a villager in northeastern Cambodia expresses her loss. Her village, along with three others, is about to be resettled to make way for the Lower Sesan 2 hydropower dam, currently under construction.

Increased competition for access to rivers and related ecosystem services is one outcome of an ongoing hydropower boom in the Greater Mekong region. The demands placed on the region’s rivers are often contradictory: a village might rely on a river for fish; all the while, a hydropower turbine upstream is impeding fish migration for energy production.

Scientists from the CGIAR Research Program on Water, Land and Ecosystems (WLE) are working to identify trade-offs in the water-food-energy nexus looking for potential win-win solutions. Their aim is to support decision makers and investors to better share the benefits and services provided by rivers.

Unintended consequences of unchecked hydropower development

The Mekong River basin is home to one-third of the world’s freshwater fish species, and is host to the world’s largest inland fishery, with some 40 million people relying on fishing for food and income.

However, the health of these fisheries may be under threat.

A recently updated series of maps, developed by WLE scientists, illustrates the scale of current hydropower development in the Greater Mekong: of the 755 current and planned dams tracked on the map, about half (392) are for hydropower generation. This development is driven by an ever-growing regional demand for energy.

“The maps offer a starting point for analyzing trade-offs,” explains Kim Geheb, leader of WLE’s focal region program in the Greater Mekong. “For example, one could start looking at economic trade-offs between land loss and agricultural productivity or economic benefits arising from electricity provision and supply to rural areas.”

While hydropower does indeed provide benefits, it is also widely acknowledged that, if not very carefully managed, it could adversely impact both local livelihoods and biodiversity.

Sorting fish caught in Tonle Sap

In fact, scientists say that unless hydropower planning and management changes, species extinctions and basin-wide declines in fisheries and other ecosystem services are certain. Similarly, another recent study has revealed that planned dam development could result in a 60 to 96% reduction in sediment flow to downstream Mekong waters, leading to a significant reduction of fisheries and soil nutrients in the Mekong Delta, resulting in adverse impact on livelihoods and potential increase in tension in the region

New livelihood solutions for resettled communities

It would seem that the risks to local communities would outweigh the benefits when communities are resettled for hydropower development. In point of fact, WLE researchers have found that the trade-offs between energy generation and livelihoods -- both in terms of risks and benefits -- are very complex.

For example, in Laos, a study of four resettled villages located upstream from the 60 MW Nam Gnouang dam showed that the villagers’ loss of access to the riverbanks meant loss of income from vegetable gardens and loss of livestock. On the other hand, access to the new reservoir meant easier access to water and a more stable fish catch throughout the year as well as more organized fish trading activities.

Scientists developed recommendations for how to establish alternative livelihood activities for all four resettlement communities and shared them with the hydropower company. As a result, the company has agreed to allow the communities to withdraw reservoir water for small-scale irrigation purposes. Furthermore, the company has expressed interest in providing support to improve fisheries management and wetland habitats for fish in the reservoir.

Innovative fish passage design to minimize trade-offs

While piloting livelihood alternatives is a large part of the WLE program, scientists are also working with the private sector to make water infrastructure more sustainable.

In Cambodia, the Lower Sesan 2 dam has been predicted to cause a 150,000 ton reduction in fish migration per year, which would dramatically threaten the food security of millions.

To limit the dam’s adverse impacts, WLE and its partners have proposed a fish passage option that could be implemented without significantly compromising the dam’s energy generation potential. The channel, which follows a naturally occurring waterway, would allow more fish to pass unharmed, would consume at most 1.2% of the reservoir water, and result in no more than a 1.1% loss of planned power production. Scientists say that this type of fish passage could easily be retrofitted to other existing dams.

Villagers of Sre Kor village, Se San District, Steung Treng Province, travel on the river near the under-construction Lower Sesan 2 hydropower dam.

Samonn Mith/WorldFish.

Taking on the recommendation made by WLE scientists, the Cambodian Fisheries Administration, in partnership with the European Union, is now commissioning a six-month feasibility study to assess the efficacy of a fish passage solution for the Lower Sesan 2, alongside monitoring and evaluation of fish migration in the river basin.

Finally, WLE supports improved dialogue about hydropower and related trade-offs. Primarily, the program’s annual forum on water, food and energy in the Greater Mekong brings together diverse stakeholders who have in the past struggled to engage in constructive exchanges. The aim is to foster constructive dialogue and support decision makers to successfully navigate the trade-offs along the nexus and create benefits for people and the environment, while leveraging water resources for energy production.

For women like Deng Kai, the costs of development are real and highlight the need for more inclusive ways to identify trade-offs and then fully identify solutions that provide the basis for all stakeholders to benefit. WLE scientists have taken a multi-pronged, solution oriented approach to water, food and energy related challenges. This recognizes that technocratic processes to managing water for diverse purposes need to be complemented with more deliberative processes that take into account social and political realities.