Assessment of glacier status and its controlling parameters from 1990 to 2018 of Hunza Basin, Western Karakorum

Ice masses and snow of Hunza River Basin (HRB) are an important primary source of fresh water and lifeline for downstream inhabitants. Changing climatic conditions seriously put an impact on these available ice and snow masses. These glaciers may affect downstream population by glacial lake outburst floods (GLOF) and surge events due to climatic variation. So, monitoring of these glaciers and available ice masses is important. This research delivers an approach for dynamics of major glaciers of the Hunza River Basin. We delineated 27 major glaciers of HRB and examined their status by using Landsat (OLI, ETM+, ETM, TM), digital elevation model (DEM) over the period of 1990-2018. In 1990, the total area covered by these glaciers is about 2589.75 +/- 86 km(2) and about 2565.12 +/- 68km(2) in 2018. Our results revealed that from 2009 to 2015, glacier coverage of HRB advanced with a mean annual advance rate of 2.22 +/- 0.1 km(2) a(-1). Conversely, from 1994 to 1999, the strongest reduction in glacier area with a mean rate of - 3.126 +/- 0.3 km(2) a(-1) is recorded. The glaciers of HRB are relatively stable compared to Hindukush, Himalayan, and Tibetan Plateau region of the world. The steep slope glacier's retreat rate is more than that of gentle slope glaciers, and the glaciers below an elevation of 5000 m above sea level change significantly. Based on climate data from 1995 to 2018, HRB shows a decreasing trend in temperature and increasing precipitation. The glacier area's overall retreat is due to an increase in summer temperature while the glacier advancement is induced possibly by winter and autumn precipitation.

Automated summary

Ice masses and snow of Hunza River Basin are crucial sources of fresh water for downstream inhabitants, but are significantly affected by changing climatic conditions. While the overall glacier area in HRB decreased from 1990 to 2018, there was a period of growth observed from 2009 to 2015. The glaciers in HRB are relatively stable compared to other regions, but are still vulnerable to climate change impacts.