Impact assessment of climate change on water resources of the Kokcha watershed: a sub-basin of the Amu Darya river basin in Afghanistan

Abstract

Abstract Climate change is one of the most concerning issues which mostly impacts water resources. This study aimed to investigate the Kokcha watershed under the effects of climate change. The study was performed utilizing the Soil and Water Assessment Tool (SWAT) considering the Representative Concentration Pathway (RCP4.5 and RCP8.5) scenarios in the periods of 2050–2059 and 2090–2099. The Model for Interdisciplinary Research on Climate (MIROC5) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) was used to prepare future climate data. The temperature indicated a rising of +2.47 and +2.85 °C in 2050–2069 considering RCP4.5, and +3.38 and +5.51 °C based on the RCP8.5 scenario through 2080–2099. Precipitation showed a −30 and −17.17% decrease based on RCP4.5, and a decrease of −9.28 and −4.52% considering RCP8.5 in the mentioned periods, respectively. The historical runoff peak shifted a month earlier with a −54.56 and −25.98% decrease considering RCP4.5 and a −29.18 and −6.45% based on the RCP8.5 scenario in the mid and end of the century accordingly. Alternatively, a second river flow peak takes shape due to rainfall in July. This study's result can be used to adapt water management to climate change in the Kokcha watershed and similar regions.