Flood susceptibility mapping in Kali River Basin, Southern India: A GIS-based analytical hierarchy process modelling

Abstract

Across the globe, floods are always a matter of concern for everyone due to the uncertainty of their occurrence and place. Though their prediction is still in the progress stage, there are enough methods available to identify the areas that have the potential to experience any specific kind of hazard. The present study is focused on an area located in the Uttara Kannada district of Karnataka and the South Goa district in Goa, which experienced a natural hazard for the first time in the form of the Kali River flood in 2019. The study aims to develop flood susceptibility maps for selected subbasins of the Kali River using integrated remote sensing techniques with the analytical hierarchy process system. Detailed analyses of numerous causative factors, i.e., elevation, slope, distance from the river, precipitation, flow accumulation, stream density, soil types, water ratio index, land use land cover, topographic wetness index, and stream power index, were carried out. The result shows that the area can be categorized into five zones ranging from very low to very high susceptibility to flooding. The prevalence of flooding in the study area can be attributed to increased sediment deposition, anthropogenic disturbances, land use and land cover patterns, gentle slopes, elevated soil moisture levels, reduced stream capacity, and limited soil infiltration capacity. The accuracy of the result was assessed using the receiver operating characteristic (ROC) method and confirmed the predictive capability of the generated map. Approximately 30 % of the study area falls within the highly susceptible zone. The outcome of the study provides valuable insights for urban planners and policymakers, assisting them in formulating strategies to mitigate the impact of future flood hazards and minimize the damages, particularly in southwest coast India.