INVESTIGATING FLOOD DETECTABILITY USING SATELLITE-DERIVED DAILY GLOBAL SURFACE WATER CHANGE AND A HIGH RESOLUTION FLOODPLAIN MASK

Abstract

 This study investigates flood detectability using global inundation maps derived from satellite images and floodplain mask. Annual total cumulative inundation extent (ATCIE: the accumulative total spatial extent of the flooded area) was derived from satellite-based daily surface water change based on 500 m Moderate Resolution Imaging Spectroradiometer (MODIS) for 2001–2015 overlayed onto newly developed floodplain mask from a global high-resolution Multi-Error-Removed Improved-Terrain (MERIT) digital elevation model. Flood detectability based on the ATCIE was then tested for 16 globally distributed historical flood events. Results indicated that standardized anomaly of ATCIE can successfully detect most of the anomalous inundation extent in historical extreme flood events. However, relatively small floods (return period < 100 year) were undetectable by ATCIE. Flood detectability of ATCIE has a correlation with the magnitude of the flood rather than basin size. Dense vegetation cover (> 40% in the basin), complexity and the intricate river basins (due to altering the flood signal by tributary rivers), or effect of cloud cover are additional potential sources of the undetectability.