Tonle Sap lake is the largest lake in Southeast Asia and home to one of the most diverse and productive ecosystems in the world. Understanding the hydrology of large lakes and reservoirs such as the Tonle Sap is crucial in water resources management. However, the hydrology of the Tonle Sap is very complicated as the surface area can fluctuate between approximately 2,000 and 16,000 km2 between the dry and wet seasons. The purpose of this research is to quantify volumetric fluctuations in the Tonle Sap using entirely remote sensing.
In this research, volumes are estimated by combining surface area estimations from satellite imagery with water level data from satellite radar altimetry. Surface areas are calculated from MODIS images taken at 8 day intervals and classified using the Normalized Difference Water Index (NDWI). Water levels are taken from processed altimetry data in the Global Reservoir and Lake Database. A relationship between surface area and water level estimations can then be created and integrated to determine volume. Results can be validated with in situ water level measurements and a digital bathymetry model of the Tonle Sap and its floodplain.