Tonlé Sap Ecosystem is threatened by Development of Hydropower Dams on the Mekong River

Future Directions –

Every year, between May and October, floodwaters from the Lower Mekong Basin reverse the flow of the Tonlé River in Cambodia. That pushes sediment-rich waters into the Tonlé Sap Lake and its surrounding floodplains and forests, which support complex food webs, migration patterns and agricultural production. The process, known as the ‘Tonlé Sap pulsing system’, provides the region with the nutrients that sustain the largest remaining area of natural wetlands connected to the Mekong River. It supplies the food resources needed to support the three million people that live around the lake and in its surrounding area.

During the wet season, Tonlé Sap expands to 60 times its normal size, to become the largest fresh-water lake in South-East Asia. There are concerns, however, that this phenomenon will not occur this year, as the regional ecosystem has come increasingly under threat from dry conditions and also upstream hydropower dams that affect sediment flow and water levels.

The energy sourced from hydropower infrastructure is integral to the development of both urban and rural areas in the Mekong Basin. Since 2000, direct investment, mainly from Chinese companies, has fueled the rapid expansion of hydropower projects in Laos and Cambodia. Rising energy prices have also encouraged China, Thailand and Vietnam to expand their own infrastructure along the Mekong.

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