Spatial distribution of supraglacial debris thickness on glaciers of the China-Pakistan Economic Corridor and surroundings

摘要

Debris-covered glaciers,characterized by the presence of supraglacial debris mantles in their ablation zones,are widespread in the China-Pakistan Economic Corridor(CPEC) and surroundings.For these glaciers,thin debris layers accelerate the melting of underlying ice compared to that of bare ice,while thick debris layers retard ice melting,called debriscover effect.Knowledge about the thickness and thermal properties of debris cover on CPEC glaciers is still unclear,making it difficult to assess the regional debris-cover effect.In this study,thermal resistance of the debris layer estimated from remotely sensed data reveals that about 54.0% of CPEC glaciers are debris-covered glaciers,on which the total debris-covered area is about 5,072 km~2,accounting for 14.0% of the total glacier area of the study region.We find that marked difference in the extent and thickness of debris cover is apparent from region to region,as well as the debris-cover effect.53.3%of the total debris-covered area of the study region is concentrated in Karakoram,followed by Pamir with 30.2% of the total debris-covered area.As revealed by the thermal resistance,the debris thickness is thick in Hindu Kush on average,with the mean thermal resistance of 7.0 x10~(-2)((m~2·K)/W),followed by Karakoram,while the thickness in western Himalaya is thin with the mean value of 2.0 x10~(-2)((m~2·K)/W).Our findings provide a basis for better assessments of changes in debriscovered glaciers and their associated hydrological impacts in the CPEC and surroundings.