Recent snow cover variation in the Upper Indus Basin of Gilgit Baltistan, Hindukush Karakoram Himalaya

Mountainous basins like the Upper Indus Basin (UIB) of Gilgit Baltistan (GB) are dependent on seasonal snowmelt and glacier melt. Monitoring of the snow-covered area (SCA) is not only vital for the overall hydrology of the Indus basin but also important to the sustainable agriculture and hydropower system. The snow-covered area in the UIB of GB was investigated for changes over the last 18 years using the Moderate Resolution Imaging Spectroradiometer (MODIS) snow product. The study area was divided into five elevation zones ranging from 877-8564 meters above sea level (m ASL). In contrast to the global cryosphere related studies, SCA in the UIB is slightly increasing. Elevation based SCA analysis also indicated that SCA is slightly increasing in each elevation zone. However, a significant amount of snow is concentrated in areas above 5000 m ASL. Due to the strong correlation between SCA and precipitation, the precipitation data also follow a similar trend. Analysis of the climatic data suggests a statistically significant increase in total monthly precipitation and relative humidity, a slight decrease in mean monthly temperature and a significant upward tendency in monthly solar irradiance data. All these trends in combination with the increasing trend in global precipitation, winter westerly disturbances and orographic precipitation are the important factors behind the slightly increasing SCA in the study area. Our results though constrained by short observation period mainly contribute to the understanding of advancing snow cover and glaciers in Hindukush Karakoram.