Hydrodynamic Flood Inundation Modelling And Risk Assessment In The Upper Banas River Basin, Gujarat

Abstract

In recent years, severe flooding has occurred in several parts of India, including Gujarat, where heavy rainfall caused extensive damage to houses, vehicles, and livestock. These events highlight the urgent need for effective flood risk management and mitigation strategies. Flood modelling plays a vital role in understanding flood behavior and supporting decision-making. The objective of this study is to evaluate the effectiveness of HEC-RAS 5.0.7 and HEC-RAS 6.0 for one-dimensional (1D) and two-dimensional (2D) flood modelling in the upper Banas River basin. A flood map was generated for the extreme flood event that occurred between 22 and 24 July 2017 and compared with observed data obtained from the State Water Data Centre (SWDC), Central Water Commission (CWC), and Shuttle Radar Topography Mission (SRTM DEM, 30 m resolution) satellite imagery. Rainfall analysis was also carried out as part of this assessment. The model outputs, including flood depth, water surface elevation (WSE), and velocity, were spatially mapped and analyzed for the duration of the event. Cross-section elevations at various locations were validated against CWC data for pre- and post-monsoon seasons. Model calibration was performed using CWC, SWDC, and site-specific observations at the dam location, ensuring reliability of the results.