Document Type : Research Paper


1 Civil Engineering Dept., University of Technology-Iraq,

2 university of technology

3 Faculty of Engineering, University of Kufa, Najaf, Iraq


In this study, the watershed’s runoff of Derbendi-Khan dam reservoir within the upper part of Diyala River reach the northeast of Iraq was modeled by Soil Water Assessment Tool (SWAT). The model calibration and validation were based on monthly measured inflow to the dam reservoir. They extended for a period between 1979 and 2008 with a warm-up period of two years, twenty-year for calibration, and eight-year for validation. Sequential Uncertainty Fitting version 2 (SUFI2) automatic calibration algorithm method used for model calibration and sensitivity analysis. Results demonstrate that the model performance for the studied watershed which is evaluated, with many statistical criteria, was very good. The sensitivity analysis pointed parameters (CH_K2, CN2 ALPHA_BF, SFTMP, SOL_AWC, and CH_N2) are the most useful parameters on runoff calibration for the studied watershed. Moreover, it was found that the average annual areal snowmelt ratio to the average annual areal precipitation during the simulation period is approximately 24%.


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