Hydrological Modelling–Based Flood Inundation and Risk Assessment of Kolhapur City, India

Abstract

Flooding is a recurrent and damaging hazard in riverine cities of India due to intense monsoonal rainfall, rapid urbanisation, and modification of natural drainage systems. Kolhapur City, located along the Panchganga River in Maharashtra, has experienced frequent flooding with significant impacts on infrastructure and socioeconomic activities. This study assesses flood inundation and flood risk in Kolhapur City using an integrated hydrological modelling and GIS-based multi-criteria framework. Rainfall–runoff processes were simulated using the Soil Conservation Service–Curve Number (SCS-CN) method, while flood hydrographs were generated using the Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS). The model was calibrated and validated using observed rainfall and discharge data, and performance was evaluated using NSE, R², RMSE, PBIAS, and RSR. Simulated hydrographs were used to generate flood inundation extent and depth maps. Results indicate that low-lying floodplain areas along the Panchganga River are highly susceptible to inundation during high-flow conditions. Flood hazard, vulnerability, and risk were assessed using the Analytical Hierarchy Process (AHP) integrated with GIS by combining physical, hydrological, socioeconomic, and infrastructure-related factors. The analysis reveals that several parts of Kolhapur City fall within high to very high flood risk zones due to the combined effects of elevated flood hazard and high socioeconomic vulnerability. The study demonstrates that hydrological modelling coupled with GIS-based multi-criteria analysis provides a robust and transferable framework for urban flood risk assessment and supports effective flood mitigation and disaster management planning.