Flood Forecasting in Upper Zab River Using SWAT hydrological Model


Flood forecasting is linked to a prior knowledge of future probable precipitation amounts. Hydrological models are a way that can enable transforming observed precipitations into stream flow. In this work a GIS based hydrologic model, SWAT is used in an Upper Zab River basin at Eske Click for flood forecasting. The importance of this work comes due to Upper Zab River is an uncontrolled river (has no dam yet); therefore it is discharged impacts of Tigris river discharges due to it is supplying about 33% from all over discharges also; impacts of amounts of sediment load comes on it. The catchment area for this watershed has an approximate drainage area of 19350.17 km2, which is divided into 9 sub basins. Results showed that the annual mean flow discharge for the period 1976 to 2006 was 392.32 m3/s which agreed with the model result which is shows that the average annual basin simulation values was 390.2 m3/s for the same period. While result simulation for the period 2015 to 2075 gave 333.70 m3/s which mean there is a reduction in mean flow discharge between two periods about 15%. Moreover, annual average basin simulation precipitation amount reduced from 1057 to 1038 mm which mean decrease about 2% between same periods .Also climate change impact was so clear in simulation results as one of climate parameters which is evapotranspration (ET) was increased from 378.3 mm to 450.2 mm which mean there is an increase about 19% between two periods simulations due to temperature increased.