Prioritization of Sardab-Rood watershed from flooding viewpoint using the SWAT model

Floods are a natural phenomenon that causes heavy losses of life and property and ‎human societies every year and people have accepted it as an inevitable event. In this research, to predict the flooding in Sardabrood basin ‎ SWAT hydrological model was used. Information needed for this research, ‎including topographic maps, land use, soil data, and meteorological data, data about daily ‎rainfall, temperature, and flow rate were prepared beforehand. SUFI2 program was used for model ‎calibration. After the calibration and optimization of the model, validation of the model in the ‎study area was done. The calibration of the model wad performed for the years 2003 to 2009 and validation was performed for ‎the years 2010 to 2013. To analyze the results of statistical indicators R2, bR2, and Nash Sutcliffe ‎coefficient were used. After model calibration the respective coefficients were, 0.77, 0.63, and 0.77  and ‎the respective validation coefficients were  0.79, 0.76, and 0.71. The sensitivity results of 31 parameters that are influential on runoff water showed that fixed parameters of groundwater base flow, its time, and the minimum amount of water necessary for groundwater base flow are more sensitive than other parameters. Number Sardabrood parameter curves were used for flood basin. Sardabrood basin was divided into 24 areas to study the flooding pattern. Finally using the above mentioned models it was concluded that sub basin No. (6)  had the first-rank with runoff 123.05, ‎‎sub basin No. (10) had the second rank with runoff in terms of flooding and sub basin No. 1 with a 12.33 has the least amount of runoff.‎