Assessment of climate change impacts on water resources of Khabour in Kurdistan, Iraq using SWAT model

The Khabour River is one of five tributaries of Tigris River and the first river flows into Tigris River contributing to Tigris Flow by about 2 BCM at Zakho Station. The area of this catchment is 6,143 km2, of which 57% are located in Turkey and 43% in Iraq with a total length of 181 km. Khabour River is the main source of fresh water to Duhok City, one of the major cities of Kurdistan Region. Hydrometeorological data over the past several decades reveal that the catchment is experiencing increasing variability in precipitation and stream flow contributing to more severe droughts and floods presumably due to climate change. SWAT model was applied to capture the dynamics of the basin. The model was calibrated at Zakho station. The performance of the model was rather satisfactory; R2 and ENC were 0.5 and 0.51, respectively in calibration period. In validation process R2 and ENC were nearly consistent. In the next stage, six GCMs from CMIP3 namely, CGCM3.1/T47, CNRM-CM3, GFDL-CM2.1, IPSLCM4, MIROC3.2 (medres) and MRI CGCM2.3.2 were selected for climate change projections in the basin under a very high emissions scenario (A2), a medium emissions scenario (A1B) and a low emissions scenario (B1) for two future periods (2046-2064) and (2080-2100). All GCMs showed consistent increases in temperature and decreases in precipitation, and as expected, highest rate for A2 and lowest rate for B1. The projected temperatures and precipitation were input to the SWAT model to project water resources, and the model outputs were compared with the baseline period (1980-2010), the picture that emerged depicted deteriorating water resources variability.