Abstract


Delayed and gradual melting of snow cover and resulting runoff plays a significant role in maintaining water resources demand in subsequent spring and summer seasons. Sabalan mountain in northwestern Iran remains snow-covered for approximately five months of the year. In this study, changes in the maximum and minimum snow-covered area (SCA), snow water equivalent (SWE), the snow-to-precipitation ratio precipitation, also annual, seasonal, and monthly minimum, maximum, and average temperature were examined using Landsat images and ground data for a 21-years period (2000–2020). The relationship between changes in SCA and SWE with precipitation and temperature variables was investigated by stepwise multiple regression. The findings revealed that the minimum SCA, mainly observed in April, decreased by approximately 34 hectares over 21 years at an annual rate of 1.62 hectares, (significance level of 5%). Among the climatic variables the maximum winter temperature increased by approximately 2.5°C during the 21-year period, i.e. an annual rate of 0.12°C. The regression model results indicated that the SWE was correlated to minimum and maximum SCA, and also the annual minimum temperature and the maximum September temperature, with multiple correlation coefficients (R) of 0.67 and 0.64 respectively. 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 Sabalan Mountain. Considering the key role of snowmelt runoff in maintaining the water demand and long term decreasing trend of glacier zone area, the region would face substantial water management challenges.