Simulation of rainfall-runoff and flood potential using modelHEC-HMS and Fuzzy Logic Case Study of Rudbal Watershed in Fars Province

Floods are one of the most frequent and destructive natural disasters that cause severe financial and financial losses every year. Flood damage is on the rise due to human manipulation of river systems and river construction. In this regard, one of the most important non-structural measures to reduce flood damage is the preparation of flood risk zoning maps and their use in spatial planning. In this regard, the HEC-HMS model was used to simulate rainfall-runoff and identify flood zones and fuzzy logic was used to overlay the subject layers and prepare the flood line map. The simulation results show the high efficiency of HEC-HMS model in simulation of rainfall-runoff of Rudball catchment and estimation of peak flood discharges. The conversion of rainfall to runoff at the surface of the Rudball Basin is mainly controlled by geomorphometry and land cover. The highest peak runoff and peak flow rates are in the upstream sub-basins of the Rudball Basin. This is due to high slope, low soil permeability, abundance of impermeable surfaces and high CN. The combination of thematic layers using fuzzy logic showed that about 8.6% of the basin area was located in areas with high risk of flooding. These zones mainly correspond to the floodplain of the Rudbal River. These lands are always exposed to floods due to the low valley and low slope. Most of the settlements in the study area are located downstream of the basin. This has increased the risk of flooding.