Hydrological model for Hemren dam reservoir catchment area at the middle River Diyala reach in Iraq using ArcSWAT model

Abstract

In this study, the catchment area’s runoff of Hemren dam reservoir within middle River Diyala reach beyond Derbendi-Khan dam at the northeast of Iraq is simulated using the Soil Water Assessment Tool (ArcSWAT-2012) model integrated with remote sensing and geographical information systems. The model was calibrated in monthly time step for the period extended from 1981 to 2000 with 2 years of warm-up period and validated with observed stream flow for years between 2001 and 2008. The model calibration and parameters sensitivity analysis were conducted using automatic calibration method within the SWAT-CUP program. The model performance for the studied catchment area was evaluated with many statistical criteria. In general, the performance of the model was good. Results of sensitivity analysis showed that there are seven parameters that mostly effect on the hydrological processes in the studied catchment; these were ALPHA_BF, CH_K2, CN2, CH_N2, SOL_AWC, REVAPMN, and GW_REVAP. Results showed that an effective runoff happens at wet seasons, and there is not continuous effective base flow from the studied catchment, and the average annual inflow volume to Hemren dam reservoir during the simulation period was 0.871 BCM, i.e., 17.42% of the overall inflow volume to Hemren dam reservoir. Furthermore, it was founded that the use of climate forecast system reanalysis of global weather station data is possible in the studied catchment area. Finally, a simple direct regression formula is determined by correlating the monthly runoff volume with monthly rainfall depth.