Evaluating the Combined Impact of Climate Change and Urbanization Patterns on Flood Risks

Urban flooding exacerbated by climate change and urban expansion poses a significant challenge in developing countries like Pakistan. This study assesses the combined impacts of urbanization and climate change on flooding in eight identified hotspots in Peshawar based on reports from the Water and Sanitation Services Peshawar (WSSP). Climate projections utilize precipitation data from CMIP6 under SSP2-4.5 and SSP5-8.5 scenarios (1980–2100). Bias correction through quantile mapping and performance evaluation identified BCC-CSM2-MR as the top-performing Global Circulation Model (GCM), with the five best models used for future projections. Land cover analysis using Landsat imagery (2000 and 2024) from USGS was processed in GIS and classified into built-up areas, barren land, cropland, and water bodies, revealing significant urban expansion. Saturation years were estimated based on annual growth rates for each hotspot. Rainfall-runoff modeling in WinTR-20 was conducted for land cover scenarios in 2000 ,2024, projected saturation years and climate projections to estimate peak flows. Results indicate rapid urbanization, with saturation expected by 2025 in Hotel Grand and Madina Colony and by 2034 in National Bank Colony and Warsak Road. Under SSP5-8.5, precipitation could increase by up to 81% with a 200-year return period. Hydrological modeling predicts rising peak flows across all catchments with NB Colony reaching 112 m³/s under extreme climate scenarios. These findings highlight the urgent need to incorporate climate and land cover dynamics into sustainable urban drainage planning to mitigate future flood risks effectively.