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Snowmelt is an important source of stream flows in mountainous areas. This study investigated the impact of snowmelt on flooding. First, the study area was divided into four zones based on elevation. Second, the Snow-Covered Area (SCA) from 2013 to 2018 was estimated from daily MODIS images with the help of Google Earth Engine. Runoff in the area was then simulated using the Snowmelt Runoff Model (SRM). As a result, short periods with high runoff and the possibility of floods were identified, while the contribution of snowmelt and rainfall in the total runoff was separated. The results showed that while the snowmelt on average accounted for only 23% of total runoff in the zone with elevation under 2000 m, the ratio increased with elevation, ultimately reaching as high as 87% in the zone with elevation above 3000 m. As the height increases, the effect of snow on runoff and flooding increases so much that it should not be ignored. However, in most hydrological studies, the effect of snow is ignored due to the lack of sufficient data about snow. This study showed that snow can be very effective, especially in high areas.

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° 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.