Assessment of Flow Changes from Hydropower Development and Operations in Sekong, Sesan, and Srepok Rivers of the Mekong Basin
Publication: Journal of Water Resources Planning and Management
Volume 139, Issue 6
Abstract
The Mekong River supports unique biodiversity and provides food security for over 60 million people in the Indo-Burma region, yet potential changes to natural flow patterns from hydropower development are a major risk to the well-being of this system. Of particular concern is the ongoing and future development of 42 dams in the transboundary Srepok, Sesan and Sekong (3S) basin, which contributes up to 20% 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 HEC ResSim and SWAT models for a range of dam operations and development scenarios. A 63% increase in dry season flows and a 22% decrease in wet season flows at the outlet of the 3S basin could result from the potential development of new dams in the main 3S rivers under an operation scheme to maximize electricity production. Water-level changes in the Mekong River from this scenario are comparable with changes induced by the current development of Chinese dams in the Upper Mekong Basin and are significantly higher than potential flow changes from the proposed 11 mainstream dams in the Lower Mekong Basin. Dams on the upper sub-tributaries of the 3S basin have very little effect on seasonal flow regimes because most of those projects are run-of-the-river dams and have small reservoir storages. The effects on hourly flow changes resulting from intra-daily reservoir operations, sediment movement, water quality, and ecology require further study. Strategic site selection and coordinated reservoir operations among countries are necessary to achieve an acceptable level of development in the basin and to mitigate negative effects in seasonal flow patterns, which sustain downstream ecosystem productivity and livelihoods.
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Acknowledgments
The authors wish to thank the Mekong River Commission for providing the databases used in this paper. Funding for this project was provided by the Critical Ecosystem Partnership Fund (a joint initiative of Conservation International, l’Agence Française de Développement, the Global Environment Facility, the Government of Japan, the MacArthur Foundation, and the World Bank). They also wish to thank Dr. Rebecca Teasley for her help during the initial stages of model development.
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Published In
Journal of Water Resources Planning and Management
Volume 139 • Issue 6 • November 2013
Pages: 723 - 732
Copyright
© 2013 American Society of Civil Engineers.
History
Received: Oct 29, 2011
Accepted: May 16, 2012
Published online: May 21, 2012
Discussion open until: Oct 21, 2012
Published in print: Nov 1, 2013
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