Comparison of MIKE NAM and AWBM models performance in simulation of daily runoff in Gokbad Catchment in Hamedan province

Apart from the understanding of the impact of land use and climate changes on the water cycle and hydrology regime, hydrological models are effective tools for designing and managing water resources. Currently, many hydrological models have been developed to simulate the basin, though choosing the right model is a challenge. To this end, a correct understanding of the model, its advantages, and limitations is necessary. In this regard, several studies have been conducted to evaluate the hydrological models performance in different regions and conditions. In the present study, the performance of two integrated hydrological and conceptual rainfall-runoff models of AWBM and MIKE NAM in the simulation of the average daily runoff in Gonbad Hamedan basin was investigated. Although both models are lumped models for rainfall-runoff process, the MIKE NAM model has a more complex structure compared to the AWBM. In addition to considering the initial conditions, MIKE NAM model is also capable of simulating snowmelt. The results of the runoff simulation during the calibration and validation periods were evaluated using two statistical indicators of the Nash-Sutcliffe efficiency (NSE) and percent bias (PBIAS). The NSE and PBIAS during the calibration and validation periods for the MIKE NAM model were 0.8, 6.3 and 0.71, -4.2; and 0.6, 14.33 and 0.55, -9.2 for AWBM model, respectively. The results showed that MIKE NAM model has a better performance in simulating daily runoff in Gonbad Moarref basin compared to the AWBM model.