Integrated Risk Assessment of Korba City Following Dam Breach Analysis of Minimata Bango Dam Using HEC-RAS 2D Modeling

This study examines potential dam breach scenarios for the Minimata Bango earthfill dam in India’s Chhattisgarh state to determine inundation risks for the city of Korba, 40 km downstream. The Hydrologic Engineering Center River Analysis System (HEC-RAS) tool was utilized to simulate multiple failure modes such as overtopping, piping, and uncontrolled releases and sensitivity and uncertainty analyses of breach parameters. Results indicate alarmingly large peak discharges for overtopping and piping situations, flood waves arriving in Korba in only a matter of hours, underscoring the narrow window for evacuation provided to authorities. Sensitivity analysis indicates that the time taken for breach formation and breach width has a critical influence on the peak discharge magnitudes and area of inundation, stressing the importance of detailed breach characterization during emergency planning. The research translated the simulations of flood inundation into hazard estimates by flow velocity and water depth and incorporated these into socioeconomic vulnerability analysis using data envelopment analysis over municipal wards and land use/land cover exposure assessment to generate detailed risk maps. Vulnerability assessment indicates that almost three-quarters of the Korba Municipal Corporation area lies in very high and high vulnerability zones, and only a limited area shows low or very low vulnerability, reflecting wide socioeconomic inequalities. Risk estimation indicates that much of the entire land surface would be classified as high-risk in different scenarios of dam failure, with the overtopping scenario posing the highest risk, followed by piping failures and uncontrolled releases. Essential infrastructure, such as roads, schools, and hospitals, was highly exposed to deep and sudden flooding under different scenarios. These results are necessary to provide for local governments in developing targeted emergency action plans, enhancing evacuation route optimization, and placing higher mitigation priority in areas with high risks under limited resources, eventually contributing to improved dam-safety management and disaster resilience for urbanizing areas.