Flood Frequency Analysis and Susceptibility Mapping in the Mahanadi River Basin Using Geospatial and Statistical Techniques

ABSTRACT This study presents a comprehensive flood risk assessment of the Mahanadi River Basin, India, through a combination of flood frequency analysis and geospatial flood susceptibility mapping. Using 48 years (1972–2020) of daily discharge data from Tikerapara, flood magnitudes for return periods ranging from 5 to 200 years were estimated using Gumbel’s Extreme Value, Pearson Type III, and Log-Pearson Type III distributions. Among them, Gumbel’s distribution provided the most conservative and best-fitting results, particularly for higher return periods. Peak discharges were subsequently scaled to the Mundali station for regional application. In parallel, a flood susceptibility map was developed using a weighted overlay analysis in a GIS environment, guided by the Analytical Hierarchy Process (AHP). Ten critical flood-influencing factors were integrated: elevation, slope, soil type, land use/land cover (LULC), drainage density, rainfall, topographic wetness index (TWI), normalized difference vegetation index (NDVI), and distances from rivers and roads. Distance from river was identified as the most influential parameter (13.80% weight), while Distance from Road had the least impact (5.77%). The resulting susceptibility map classified the basin into four zones: Very High (0.05%), High (29.32%), Moderate (66.86%), and Low (3.78%) flood risk. These outputs offer critical insights for targeted flood mitigation, zoning, infrastructure design, and disaster preparedness. The AHP-GIS framework developed in this study is scalable and adaptable to similar flood-prone regions across India and other monsoon-affected areas worldwide, contributing to climate-resilient planning and sustainable water resources management.