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Water level response to hydropower development in the upper Mekong River.
1Asia International Rivers Center, Yunnan University, Kunming, China. lsj@mail.ynu.edu.cn
Ambio
|July 4, 2008
Summary
Upper Mekong River dams show limited downstream effects on annual water levels, but regulate dry season flow. Long-term trends are influenced by climate change and solar activity.
Area of Science:
- Hydrology
- Environmental Science
- Climate Science
Background:
- Transboundary environmental changes in the Mekong River system are a significant research area.
- Divergent opinions exist regarding the impacts of upper Mekong River dams on water levels.
Purpose of the Study:
- To quantitatively examine the characteristics of the upper Mekong River's mainstream water-level process at multiple timescales.
- To assess the response of water levels to cascade dam development.
Main Methods:
- Analysis of water level records from 1960 to 2003 at three mainstream sites in the upper Mekong River.
- Quantitative examination of water level processes at multiple timescales (annual, wet period, dry season, monthly, daily, hourly).
Main Results:
- Annual mean and wet period mean water levels show increasing trends at Jiuzhou and Yunjinghong, influenced by climate change and solar activity.
- Interdecadal variations in water levels exhibit similar patterns across sites during dam construction.
- Dry season water levels show regulation by existing dams, with varying trends at different sites.
- Downstream dam effects are minimal on annual and wet season mean levels but significant on daily and hourly timescales.
Conclusions:
- While large-scale factors influence long-term trends, existing upper Mekong dams exert some regulation on dry season flows.
- The downstream impact of current dams on overall water levels is limited, becoming more apparent at finer timescales.
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