Flood Risk Assessment for the Major River Basins in India

Flood risk assessment is a key aspect while taking preventive measures for the projected future floods and associated losses. The estimation of flood risk incorporating the reservoir effects on a sub basin scale is still lacking for India. In this study, we used the H08 land surface model combined with the Catchment based Macroscale (CaMa) flood hydrodynamic model. We calibrated the combined model for eighteen major river basins of India for one gauge station each. We considered the effect of 51 major dams in the CaMa flood model while simulating river flow and flood dynamics. We forced the well-calibrated combined model with observed parameters from India Meteorological Department (IMD) to run simulations from 1901 to 2020. We generated the flood depth maps for the historical worst flood case on sub basin level. We used gridded population data from the Global Human Settlement Layer (GHSL) data set to determine the exposure. Further, we used vulnerability and hazard for each sub basin along with exposure to estimate risk. We also accessed the impact of existing dams on flood dynamics. The study will provide sub basin scale information on the Vulnerability, Hazard, Exposure and Risk.