Performance Evaluation of SWAT and IHACRES Models to Simulate Runoff in Khorramabad Watershed

Rainfall-runoff modeling in watersheds plays an important role in water resources management, river engineering, flood storage and designing control structures. Diversity of available models makes it difficult to choose the most appropriate model for certain objectives. In this research, two models, namely a lumped model (IHACRES) and a semi-distributed model (SWAT) were applied to simulate runoff in Khorramabad watershed. After overlapping maps, 232 Hydrologic Response Units (HRU) were obtained. Sensitivity analysis, calibration and validation purposes of SWAT were performed using SUFI2 algorithm for runoff simulation. For calibration and validation of the models, time periods of years 2004-2008 and 2009-2010 were used, respectively. Effectiveness evaluations of the models were conducted using R2, NS, bR2 and RMSE coefficients. Obtained values of this coefficient for the lumped model were equal to 0.72, 0.53, 0.36 and 0.15 m3 s-1 and for the semi-distributed model were 0.66, 0.63, 0.44 and 0.17 m3 s-1, respectively. The results showed that in spite of simplicity of the lumped model, its performance was near to semi-distributed model, so that, both the models were suitable for using in the studied watershed. Therefore we can use these models for simulating hydrographs in the same areas with respect to availability of data.