Impact Assessment of Built Environment on Urban Flooding Using SCS-CN Method

Unprecedentedly frequent occurrences of urban flooding are becoming a major concern for urban planners in several Indian cities. The primary causes of this urban disaster are changes in rainfall patterns brought on by global climate change and rapid changes in Land Use Land Cover (LULC) types. The amount of impervious land cover in cities has gradually grown due to growing built areas and modifications to LULC, transforming rainfall into surface runoff that is eventually removed by the local sewage system. This has several consequences, including increased surface runoff and decreased water storage capacity of soil. Despite some initiatives, the problem of urban flooding stays unresolved. In the case of Kolhapur, Maharashtra, India, a proper study has not been done on the impacts of change in land use and land cover on urban flooding. This study analyzes the transmogrification of urban morphology and evaluates the impact of urbanization in terms of land use land cover considering two major factors: surface runoff and the potential maximum water storage capacity of soil using the SCS-CN method. It was found that the built land cover has increased by 164% whereas the un-built land cover has reduced by 33% in the study area over the study period (1985–2020). This increase in built land cover has increased the surface runoff by 37% and decreased the water holding or storage capacity of soil by 20% of the study area. This study serves as a foundation for creating sustainable urban flood mitigation strategies for the city and other comparable places.