Flood hazard mapping is a basic tool for flood preparedness and mitigation activities, including flood insurance programs. For natural disaster management, it is necessary to monitor continuously. However, monitoring flood area is very difficult due to poor accessibility and lack of gauge data. Remote sensing can provide large spatial coverage and nonintrusive measurement over the surface. Study area is the Tonle Sap Lake, along with the Tonle Sap River, forms a unique hydrological system due to monsoon climate. The reverse flow of the Tonle Sap River during wet season results in intensive flooding that enlarges the lake over vast floodplain and wetland where covered with forests, shrubs, etc. The aim of this research is to generate inundation map using time series satellite image data (ALOS PALSAR and MODIS). We used InSAR coherence map for analysis of flood areas. And we detected inundation areas using GVMI (Global Vegetation Moisture Index) from MODIS image. The total flooded areas during wet season were effectively mapped by coherence maps and GVMI threshold.