Snow is one of the most important climatic-hydrological variables that plays a vital role in watersheds. This importance is multiplied in Iran, as Iran is a warm country which is dependent on melting snow for the warm seasons. The purpose of this study is to monitor and project snowfall changes in Iran. To this end, we used two sources of data; the daily snow cover data of MODIS Terra satellite with horizontal resolution of 0.01 arc degree during the period of 2000–2019 for snow monitoring, and bias-corrected output of CMIP6 models under SSP scenarios for the period 2021–2100 with horizontal resolution of 0.5 arc degree for projection of snow cover. According to satellite data, spatial snow cover often occurs in the Alborz and Zagros altitudes with a snow boundary of 4000 m above sea level (MASL), and most snow cover occurs in January. The snowfall projection for the future period showed a significant downward trend at level of 0.05, the slope of which is steeper in the cold months of the year (December to February). Caspian Sea, Persian Gulf, and Oman Sea basins show a more decreasing trend of snowfall than other basins. Under a pessimistic scenario of SSP 5–8.5 in the period 2061–2100, snowfall will decrease by 6.8–7.4 cm in the Persian Gulf and Oman Sea basins for the high Zagros highlands in January. Due to the reduction of snowfall in the main basins of Iran, integrated watershed management is crucial in the field of water resources.

Keywords