Assessment of flow changes from the operation of dams in the Mekong basin

Hydro development is taking place rapidly on tributaries in the Mekong river basin, stimulated by the need for economic growth and energy security, as well as the advantage of renewable and non-fossil fuel generation. Concerns have arisen about potential impacts on biodiversity, food security, and livelihood as a result of changes in natural flow patterns, particularly in relation to the ongoing and future development of 41dams in the transboundary Srepok, Sesan and Sekong (3S) basin, which contributes up to 20 per cent of the Mekong’s annual flows and provides critical ecosystem services to the downstream Tonle Sap lake and the Mekong delta. To assess the magnitude of potential changes, daily flows were simulated over 20 years using the SWAT and HEC ResSim models for a range of dam operations and development scenarios.