Remote Sensing of Ecological Responses to Changes in the Hydrological Cycles of the Tonle Sap,

largest freshwater lake in Southeast Asia, exhibiting large changes in spatial extent between the wet and dry seasons. The extensive wetlands around the Tonle Sap support a high level of biodiversity of great importance not only to the Tonle Sap but to the entire Mekong river system. Time-series of MODIS 500m 8 Day Surface Reflectance product imagery covering the period 2000-2005 were used to establish seasonal flooding cycles and flooding extents, and ASTER surface reflectance product was used to map vegetation distributions. Water resource use on the Mekong upstream of the Tonle Sap is reducing and moderating the monsoonal flood pulse which sustains the lake and floodplain system. This can be linked to the timing of large dam construction within the Mekong River basin. There is an urgent need to develop more effective cross-border management plans and cooperation for the water resources of the Mekong system before the unique and economically important Tonle Sap region slips into further decline