Modeling Flash Flood Events in The Arid And Semi Arid Regions of The Luni River Basin India

The Luni River Basin situated in the arid and semi-arid regions of Rajasthan, faces growing challenges related to flooding, despite receiving low annual rainfall, with some areas recording less than 250 mm. The Luni being an ephemeral river, is primarily influenced by monsoonal precipitation which drives the majority of surface runoff within the basin. However, the increasing frequency and intensity of extreme rainfall events have significantly altered its hydrological dynamics. These sudden and intense downpours increasingly trigger flash floods, which disrupt the already fragile water dynamics of the region. Flood events in the Luni Basin are particularly severe due to the interplay of geomorphological and anthropogenic factors. The basin predominantly has sandy soil, coupled with high salinity levels result in limited infiltration capacity. This, combined with enhanced surface runoff exacerbates the frequency and impact of floods. Moreover, extensive groundwater extraction, rapid land-use changes, urbanization, and the expansion of irrigation systems reliant on canal-fed networks have heightened the basin’s susceptibility to flooding. These floods not only damage critical infrastructure and agricultural lands but also complicate water storage and long-term resource management strategies. This study focuses on modeling the flash flood events in the Luni River Basin over the period from 1979 to 2024 to better understand their impacts on the arid and semi-arid regions of Rajasthan. Advanced hydrodynamic models, such as HEC-RAS and ANUGA, have been utilized to simulate these flood events, providing a detailed representation of flood behavior and extent. The accuracy of these models has been enhanced through validation against satellite-derived data for recent events. This ensures reliable flood extent mapping, offering valuable insights into the basin's hydrological responses and supporting the development of effective flood mitigation and management strategies.