Prediction of runoff changes in Zarrineh river basin under climate change conditions via hydrological simulation

Subject Areas :

Maliheh Rahvareh ¹ , Baharak Motamedvaziri ^{2 *} , Alireza Moghaddamnia ³ , Ali Moridi ⁴

1 - Ph.D candidate of Watershed Management Science and Engineering, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran.
2 - Assistant professor, Department of Range and Watershed Management, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran.
3 - Associate Professor, Department of Rehabilitation of Arid and Mountainous Regions, Faculty of Natural Resources, University of Tehran, Karaj, Iran.
4 - Assistant professor, Faculty of Civil, Water and Environmental Engineering, Shahid Beheshti University, Tehran, Iran.

Received: 2021-11-28 Accepted : 2021-12-22 Published : 2021-02-19

Keywords: Zarrineh river basin, Climate Change, SWAT model, HadGEM2-ES, RCP scenarios runoff,

Abstract :

It is necessary to study the behavior of the river under the effect of climate change, especially the runoff in the future periods. This study evaluated the effect of climate change on the runoff of Zarrineh river basin (the largest sub-basin of Lake Urmia) considering the General Circulation Model (GCM) under two Representative Concentration Pathway (RCP) scenarios (2.6 and 8.5). For this purpose, temperature and precipitation changes in the future periods in Zarrineh river basin were studied using climate data of Had GEM2-ES model during the period 2025-2050. The Climate Change Toolkit (CCT) was used to downscale climate data. The Soil and Water Assessment Tool (SWAT) hydrological model was used to evaluate the impact of climate change on runoff the basin. Also, the SWAT model was calibrated and validated using monthly runoff. Then, downscaled results of the general circulation model interoduced to the SWAT model. And runoff changes at the outlet of the basin were simulated during 2025-2050. The results showed that the SWAT model has good performance in runoff simulation. The average results of the CCT model revealed that the maximum and minimum temperatures would increase in 2025-2050. The annual precipitation could increase 3.6% under RCP 2.6 and decrease 2.9% under RCP 8.5. The seasonal trends in the runoff showed a decreasing trend in winter, spring and summer while an increasing trend in autumn. Annual runoff under RCP 2.6 and RCP 8.5 has decreased 6.5% and 30% respectively. Which subsequently reduces the discharge of this river to Lake Urmia.