Cities face significant flooding risks due to dense populations and valuable assets, making comprehensive flood risk assessment crucial for effective management. This study evaluates flooding risk in a potential urban growth area of Dhaka City, Bangladesh, employing an integrated approach. Flood hazards were assessed using a one-dimensional hydraulic model, while vulnerability was evaluated through the analytical hierarchy process (AHP), a multicriteria decision-making method. Different probability distribution functions (PDFs) were applied for flood frequency analysis based on discharge and water level, with the Log-Pearson Type-III PDF identified as the best fit. This PDF was used to estimate discharge and water levels for 200- and 500-year return periods. Simulations were conducted using the Hydrologic Engineering Center’s River Analysis System model, calibrated with Manning’s roughness coefficient. Results indicated that approximately 57% and 65% of the study area would be inundated during 200- and 500-year floods, with maximum depths of 8.6 and 9.45 m, respectively. Vulnerability was assessed using factors such as population density, land use, and proximity to key infrastructure, resulting in a classified vulnerability index map by the AHP method. Integration of hazard and vulnerability maps revealed that 40% of the area faces lower flood risk, while 60% has medium to very high risk, aiding urban planners and policymakers in selecting effective flood mitigation strategies.
Rahman et al. (Mon,) studied this question.