Flood Frequency Analysis on Ganga Basin Catchment using Geospatial Techniques

Flooding is one of the most devastating natural disasters, significantly impacting human lives, infrastructure, and ecosystems. Severe rains when combined with a lack of proper infrastructure in urban areas can lead to floods. Thereby accurate flood predictions and modelling are essential for efficient flood control in such environments. A critical component of this process is obtaining reliable hydrological outputs over watersheds, which forms the foundation of precise flood forecasting. Flood inundated areas can be generated by hydrological and hydraulic modelling to provide valuable insights into high-risk zones. Modelling helps in interpreting timely and reliable flood information from the generated flood maps to reduce damages in flood areas. In this study Hydrological Response in the form of runoff is computed for a region of the Upper Ganga basin, India by using HEC Series and thus flood inundation maps were generated for different return periods. Data sets required for the study included satellite images, digital elevation model, daily precipitation and soil map. To model flood inundated areas for a return period of 2,5,10,25,50,100 years, HEC-HMS and HCE-RAS were employed. Flood inundation maps were generated and flood risk areas were identified for different return periods. Results showcased that 2-years return period flood inundates approximately 0.29 sq. km, accounting for nearly 2% of the total study area and 100-years return period flood inundates approximately 4.42 sq. km covering nearly 31% of the study area. This study provides a framework for similar research in other flood prone areas and suggest implementation of low-impact development strategies for regions prone to frequent flooding in the study area. The findings underscore the importance of integrating advanced flood modelling techniques with historical data to enhance disaster preparedness and resilience.

Keywords: Climate Change, Hydrological Modelling, Flood Inundated Areas, Return Period.