This study evaluates a numerical flood model simulation of the 2000 Yigong dam-break flood in the Eastern Himalaya by mapping high water marks and comparing them to the model. Vegetation change in remote sensing data was used to identify trim lines marking the flood extent. Over 564m of trim line was mapped from Google Earth imagery, matching well with the model. Preliminary analysis of Landsat 7 imagery suggests better resolution and accuracy over a longer 172km mapped trim line section. Ten large landslides totaling 2.94 square miles of erosion were also mapped from the imagery, indicating the spatial impact of the flood. The good match between mapped trim lines and modeled high water marks validates the numerical model for simulating floods