Urban Flooding Management Integrating Low Impact Development Under Climate Change Scenarios

Abstract This study examines urban flooding in Pokhara, Nepal, using PCSWMM-based hydrological modeling, combined with Low Impact Development (LID) strategies and future climate change projections. Land Use Land Cover (LULC) analysis revealed rapid urbanization, with built-up areas increasing from 7.3% in 1990 to 62.1% in 2023. Climate projections under SSP2-4.5 and SSP5-8.5 scenarios indicate a rise in extreme rainfall events, particularly under SSP5-8.5, suggesting a higher risk of urban flooding in the future. Analysis of precipitation data (1973–2023) identified the Log Pearson Type III distribution as the best fit, supporting the development of Intensity-Duration-Frequency (IDF) curves. The study area was divided into 28 subcatchments and evaluated under two scenarios: LID-only and a combined approach with enhanced drainage and reduced LID. Results showed that LID interventions significantly reduced runoff. The findings highlight the importance of integrating both nature-based and structural solutions to improve urban flood resilience amid increasing climate extremes.