- From December 2014 World Rivers Review
Climate change will result in many hydrological changes of relevance to hydropower generation in the Mekong Basin, says Dr. Richard Beilfuss of the International Crane Foundation, a hydrologist and expert on the climate risks of large hydropower dams who has been studying Mekong climate risks for the German aid agency GIZ.
Climate change is expected to affect temperature, rainfall and snowfall patterns, the timing and volume of river flows, frequency of droughts and floods, evaporative water loss, glacier melting, and groundwater.
The Mekong is facing huge growth in large hydropower projects, yet planning and design of dam projects in the basin are not taking into account climate risks. Most hydropower projects are designed on the basis of recent climate history and the assumption that future hydrological patterns will follow historic patterns. This notion is no longer valid. Under future climate scenarios, a hydropower station designed and operated based on the past century’s record of flows is unlikely to deliver the expected services over its lifetime. It may be over-designed relative to droughts, and under-designed relative to extreme inflow events in the future.
“Uncertainty about future hydrology presents a great challenge for infrastructure planning and engineering,” says Beilfuss. “Water resource developers and managers depend on accurate hydrological models. Yet the Mekong’s future hydrologic regime is unclear – some studies project increases in Mekong runoff, while others project decreases. Any infrastructure will have to contend with the impact of more frequent extreme floods and droughts.”
In addition to risks to hydropower projects, projected impacts of climate change on human livelihoods and biodiversity in the densely-populated Mekong Delta are expected to include decreasing food production capacity (especially rice and aquaculture production), increased incidence of flood and drought damage, and loss of productive wetlands due to sea-level rise and land submersion, according to the study’s co-author, Dr. Tran Triet, of the International Crane Foundation and University of Ho Chi Minh City. This could exacerbate the negative impacts associated with a Mekong dam boom on the basin’s fishing and farming communities. The basin will be further affected by large-scale irrigation development, land use change, industrialization and urbanization.
“There is an urgent need for comprehensive studies that assess cumulative impacts of river basin development and climate change in the Mekong Basin,” says Beilfuss. “Such studies would ensure sound decision-making about the future of hydropower development in the basin.”
The analysis also notes that various development alternatives have been suggested that are more robust to climate risks and impacts than large dams. Suggestions include innovative systems for tapping the power of the mainstream in ways which do not require dams across the full breadth of the river channel; upgrading existing infrastructure; investing in infrastructure that is reversible or can be used under a range of conditions as climate changes; building larger safety margins in infrastructure to cope with extreme events; promoting non-infrastructure adaptation strategies, such as investing in floodplain restoration, and reducing decision-time horizons for more rapid responses, such as the addition of smaller and decentralized infrastructure.