Abstract

The water resulting from the melting of snow cover in mountainous regions plays a crucial role in meeting water demands due to the delayed melting period and gradual runoff distribution over subsequent months. Mount Sabalan in northwestern Iran contains glacial water reserves at higher altitudes and remains snow-covered for approximately five months of the year at lower elevations. To date, no research has been conducted on the response of snow cover and its water resources to variations in climatic parameters over consecutive statistical periods. Therefore, in this study, using Landsat series images and ground station data over a 21-year period (2000–2020), changes in the maximum and minimum snow-covered area (SCA), snow water resources (SWR), precipitation, snow water equivalent (SWE), the snow-to-precipitation ratio, and annual, seasonal, and monthly minimum, maximum, and average temperatures were examined. The relationship between changes in SCA and SWE with precipitation and temperature parameters was analyzed using stepwise multiple regression. The findings revealed that the minimum SCA (primarily observed in April), associated with glacier accumulation at higher altitudes, decreased by approximately 34 hectares over 21 years at an annual rate of 1.62 hectares, with a significance level of 5%. Additionally, among the climatic parameters, the maximum winter temperature increased by approximately 2.5°C over the 21-year period, at an annual rate of 0.12°C. The regression model results indicated that the minimum and maximum SCA, in addition to SWE, were correlated with the annual minimum temperature and the maximum September temperature, respectively, with multiple correlation coefficients (R) of 0.67 and 0.64. Furthermore, SWR showed a multiple correlation coefficient of approximately 0.94 with SWE, the maximum summer temperature, and the annual minimum temperature. The results of this study demonstrated a significant reduction in snow resources at higher altitudes of Mount Sabalan. Although these snow resources, due to their limited extent and gradual declining trend, currently do not have a significant impact on changes in snow water resources, they play a vital role in meeting the region's water needs during warm seasons and drought conditions, especially in the absence of precipitation and the melting of lower-altitude snow reserves. Therefore, if this trend continues and glacial reserves are lost in the long term, managing snow water resources in the studied area will face considerable challenges.