Evaluating glacier dynamics using temporal remote sensing images: a case study of Hunza Valley, northern Pakistan

Abstract

Glaciers are the largest freshwater repository on the earth surface. Northern Pakistan is covered with some of the largest midlatitude glaciers in the world. Most of the recent studies on the region lead to contradictory results that glaciers in the Karakoram ranges have shown either advancement, retreat or stable behaviors and therefore coin the term “Karakoram anomaly.” In the present study, temporal Landsat satellite images, acquired in the years of 1977, 1999, 2001, 2007, 2009 and 2014, were used to evaluate the temporal dynamics of the selected glaciers in the Hunza Valley, northern Pakistan, including the Batura, Passu, Ghulkin and Gulmit. The glaciers outlines were extracted using NDSI and slope gradient, followed by manual editing. The Landsat-derived glacier inventories were verified through the fine-resolution WorldView-2 satellite image and field observations. Evaluating the temporal glacier inventories reveals that the selected glaciers are retreating; however, the melting rate is varying depending on the supra-glacier debris cover. The melting or advancing of glacier is also influenced by the mean annual temperature and precipitation records. The study should assist in predicting the future climate of the region.