Using Landsat images to monitor changes in the snow-covered area of selected glaciers in northern Pakistan Using Landsat images to monitor changes in the snow-covered area of selected glaciers in northern Pakistan

最小化 最大化

Vol14 No.10: 2013-2027

Title】Using Landsat images to monitor changes in the snow-covered area of selected glaciers in northern Pakistan

Author】Chaman GUL1,2; KANG Shi-chang1,2,3*; Badar GHAURI4; Mateeul HAQ5; Sher MUHAMMAD2,3; Shaukat ALI6

Addresses】1 State Key Laboratory of Cryosphere Science, Northwest Institute of Eco-Environment and Resources,  Chinese Academy of Sciences, Lanzhou 73000, China; 2 University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China; 3 CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China; 4 Institute of Space Technology (IST), Karachi, Pakistan; 5 Space and Upper Atmosphere Research Commission (SUPARCO), Karachi, Pakistan; 6 Global Change Impact Studies Centre (GCISC), Ministry of Climate Change, Islamabad, Pakistan

Corresponding author】shichang.kang@lzb.ac.cn

Citation】Gul C, Kang SC, Ghauri B, et al. (2017) Using Landsat images to monitor changes in the snow-covered area of selected glaciers in northern Pakistan. Journal of Mountain Science 14(10). https://doi.org/10.1007/s11629-016-4097-x

DOI】https://doi.org/10.1007/s11629-016-4097-x

Abstract】Landsat satellite images were used to map and monitor the snow-covered areas of four glaciers with different aspects (Passu: 36.473°N,74.766°E;Momhil: 36.394°N,75.085°E;Trivor: 36.249°N,74.968°E;andKunyang:36.083°N,75.288°E)in the upper Indus basin, northern Pakistan, from 1990-2014. The snow-covered areas of the selected glaciers were identified and classified using supervised and rule-based image analysis techniques in three different seasons. Accuracy assessment of the classified images indicated that the supervised classification technique performed slightly better than the rule-based technique. Snow-covered areas on the selected glaciers were generally reduced during the study period but at different rates. Glaciers reached maximum areal snow coverage in winter and pre-monsoon seasons and minimum areal snow coverage in monsoon seasons, with the lowest snow-covered area occurring in August and September. The snow-covered area on Passu glacier decreased by 24.50%, 3.15% and 11.25% in the pre-monsoon, monsoon and post-monsoon seasons, respectively. Similarly, the other three glaciers showed notable decreases in snow-covered area during the pre- and post-monsoon seasons; however, no clear changes were observed during monsoon seasons. During pre-monsoon seasons, the eastward-facing glacier lost comparatively more snow-covered area than the westward-facing glacier. The average seasonal glacier surface temperature calculated from the Landsat thermal band showed negative correlations of -0.67, -0.89, -0.75 and -0.77 with the average seasonal snow-covered areas of the Passu, Momhil, Trivor and Kunyang glaciers, respectively, during pre-monsoon seasons. Similarly, the air temperature collected from a nearby meteorological station showed an increasing trend, indicating that the snow-covered area reduction in the region was largely due to climate warming.

Keywords】Snow-covered area; Glacier; Global warming; Classification technique; Northern Pakistan