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 streamflow. In this work a GIS based hydrologic model, SWAT is used in an Upper Zab River basin atEske Click for flood forecasting. The importance of this work comes due to Upper Zab River isan uncontrolled river (has no dam yet); therefore it is discharged impacts of Tigris riverdischarges due to it is supplying about 33% from all over discharges also; impacts of amounts ofsediment load comes on it. The catchment area for this watershed has an approximate drainagearea of 19350.17 km2, which is divided into 9 sub basins. Results showed that the annual meanflow discharge for the period 1976 to 2006 was 392.32 m3/s which agreed with the model resultwhich is shows that the average annual basin simulation values was 390.2 m3/s for the sameperiod. While result simulation for the period 2015 to 2075 gave 333.70 m3/s which mean thereis a reduction in mean flow discharge between two periods about 15%. Moreover, annualaverage 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 insimulation results as one of climate parameters which is evapotranspration (ET) was increasedfrom 378.3 mm to 450.2 mm which mean there is an increase about 19% between two periodssimulations due to temperature increased.