The Mekong River - survival for millions Lake Tonle Sap Mekong Delta Mekong Delta Wetland

Expected Effects of Climate Change in Mekong Basin Precipitation & River Flow: Precipitation and runoff increase of 13.5 % predominantly from wet season increases Increase in dry season precipitation in northern catchments and decrease in southern catchments. Increase in Mekong River flow in both wet and dry seasons –Wet season increase = 15% above PP –Dry season increase =30% in upper portions Increase in total annual runoff of 21% + increase in flooding

Greater Mekong/ Lancang

Area inundated at various levels of sea level rise in Vietnam Source: Dasgupta, et. al, 2007) Area Inundated in the Mekong Delta (Sea Level Rise = 1m) (Source: MRC Technical Paper No. 24, September 2009)

Maintaining the Flows that Nourish Water Sediment Nutrients Information

River erosion due to reduction in sediment

Objective Counteract the effects of climate change Maintain water and sediment flows to preserve ecosystem health and food production At any level or pace of development To inform decisions on siting, design and operation of dams to:

Sediment Capture will have High Impact On the most biologically productive features of the river system –Floodplains—84,000 km 2 –Wetlands –e.g. Tonle Sap –Deep pools—400 mapped –Delta—most endangered –Near shore ocean—nutrient dependent On the economic value of reservoir depends on maintaining storage capacity

Project Premise At any level of development, there are better and worse choices in –Siting –Design –Operation To move sediment through dams and reduce impacts on food/ecosystem productivity

We need to learn about Sediment

Good for Us and Good for Them