Performance of SWAT Model in Quantitative and Qualitative Simulation of Runoff and Watershed Protective Measures in Zarrinehrood Basin

This study aims to simulate runoff and runoff quality of Zarrineh river basin by SWAT model. Calibration and verification were done respectively with monthly runoff statistics in SWAT CUP by SUFI2 method for 1992-2013, for 12 sub basin, 226 HRU and monthly nitrate data for 2006-2009. The highest runoff sensitivity and runoff quality with minimum Pvalue and maximum absolute value Ttest belong to soil cure number and nitrogen hydrolysis. The maximum number in calibration and verification belonged to Zarrineh dam station by R2=NS=0.81 and minimum number belonged to Janagha station by R2=NS=0.47. The value of these two coefficients in calibration of nitrate in all basin were 0.58 and 0.44 and their coefficient in verification were 0.51 and 0.42 respectively. Statistical results showed that a good performance in the SWAT model simulation of monthly flow and nitrate in the basin of Zarrineh river. Then the simulation was conducted by best management practices model. In this study protective measures watershed simulated stone lines, contour lines and mulching considered as a management solution. The best solution was contour lines by 17.89% reduced nitrate amount input to Urmia Lake see also 11.17% discharge the ground water.