A sustainable approach to evaluate the impact of urban sprawl on coastal flooding in Oshiwara watershed, Mumbai, India

Urban sprawl has emerged to be the most important and expensive part of the ecosystem with so many hazardous effects on the natural environment. Flooding has a tremendous impact on the cities, encompassing the water cycle management by collective disciplines of engineering, environmental, social, and economic sciences. This study focuses on analysing urban flooding and incorporating site-specific sub-catchment spatial strategies and management techniques considering human interactions. The Oshiwara watershed in Mumbai, India was delineated which is responsible for urban flooding along with the storm surges in the study region. The flood inundation mapping was obtained for different return periods by implementing hydrologic-hydraulic modeling and further, spatial hazard zones were identified concerning non-heuristic drivers for the 100-year return period. Subsequently, four impact maps namely infrastructural, social, economic, and environmental were identified along with the overall risk. Management interventions involving flood risk mitigation, stormwater harvesting, and water reuse were analyzed to mitigate these impacts. This provides a sustainable approach to spatially mitigate effects at vulnerable zones, instead of adopting a lumped approach for decision-making. Further, it assists the water planners to deploy planning and management interventions at specific risk locations. Thus, this study provides a suitable platform for urban planners to incorporate decisions by focusing on spatial high-risk locations.