Climate change impacts on snow cover area and snowmelt runoff in the Ajichai Basin-Iran

During snowmelt in mountainous areas, runoff can play an important role in providing water to the region. This study examined the effect of climate change on runoff in Ajichai, Iran, since it affects air warming and faster melting of snow and ice. Using the sixth report provided by IPCC, the future temperature and precipitation in the years 2015-2100 were predicted using two scenarios, SSP1-2.6 and SSP5-8.5. According to the results, the average annual minimum and maximum temperatures would increase by 1 degrees during this period, but precipitation would decrease by about 3%. Based on the Snow Runoff Model (SRM) model and the snow cover area (SCA) obtained from Google Earth Engine and MODIS daily images from 2013 to 2018, runoff caused by snow melting was simulated. Based on the Pearson correlation coefficient between snow cover and temperature and precipitation, the SCA was estimated in three decades: 2031-2040, 2061-2070, and 2091-2100. With reasonable accuracy, the SRM was able to simulate runoff. In the SSP1 scenario, the SCA in spring and winter will remain the same throughout all three decades, but in the SSP5 scenario, it will decrease by about 17%. In the future, the runoff will decrease by up to 6% in the winter and increase in the spring.