Probabilistic flood risk assessment using coupled hydrologic and 2D-hydraulic model in the Jhelum River, Northwest Himalayas

Keeping in mind the susceptibility to flooding-related disasters in the past, the need was identified for flood risk assessment using recent modelling techniques in the data-scarce River Jhelum, India. This study conducted a preliminary rainfall frequency analysis to find the best fit statistical model for calculating peak flow rates for multiple return periods. A framework was followed for the spatio-temporal delineation of flood-prone areas by integrating the watershed modelling system (WMS), Hydrologic Engineering Center-Hydrologic Modelling system (HEC-HMS), and two-dimensional Hydrologic Engineering Center-River Analysis System (2-D HEC-RAS) for different return period design floods. The 2-D unsteady state flood modelling in HEC-RAS showed the river overflowing its flow path for all the return periods, with 55% of the Srinagar city inundated in the 100-year event. The simulated flood depths and velocity maps for every design flood scenario are shown. The 2-D simulations yielded encouraging results compared to the most recent flood event.