Dam break study and its flood risk in Gurara watershed-Nigeria under varied spatio-temporal conditions by integrating HSPF and HEC-RAS models

This study focuses on the flood disaster and risk that can potentially occur in the event of a dam break in the Gurara watershed, Nigeria. The aim is to evaluate the effects of land use and land cover (LULC) and hydroclimatic variability on the aforementioned dam. This is done through integration of Hydrological Simulation Fortran Program (HSPF), hydro-dynamic models and field observations. The simulation result presents the extent of the flood downstream, which inundates 274.6 Km2 (27,460 ha) of the watershed, that includes a peri-urban Jere town with a total population of 9912 and 6000 ha of irrigation area that has the potential to produce 100,000 metric tons of food in four circles per year. Further analysis of the result shows that the flood hazard map of the flooded area produced a varied index for each scenario, but it shows that the hazards increase with an increase in the literal inflow into the dam from the upstream runoffs. The hazard maps identify risks in vulnerable areas. The downstream area experiences diverse exposure based on the proximity of LULC class to the prone zones. This research presents details about the possible disaster associated with dam collapse in nearby communities.