Lake-ice Contacted Glacier Changes And Glacial Lake Evolution In The Karakorum-Himalayan

Glacier retreat is a powerful driver of change in the development of mountain hydrology and landscapes,posing multiple risks and offering new options for human survival.In the Karakoram-Himalayas,current glacier loss rates have been studied to some extent,but the associated future extent of glacier loss and formation of glacial lakes in terms of area and volume has not been well explored.This study analyzes glacier and glacial lake development in conjunction with current(1990-2018)and future(2050/2100)glacial-lake contact glaciers in the Karakorum-Himalayas.The total glacier area(volume)in the study area decreases from 5426.93 km~2(655.31±144.16km~3)in 2005 to 4257.89±766.42 km~2(316.63±60.15 km~3)in 2100,a decrease of 21.54%(51.68%).The area(number)of potential glacial lakes of the associated glaciers increased from85.83±12.87 km~2(326)in 2050 to 185.69 km~2(749)in 2100,an increase of 1.16 times(1.31times),while the corresponding lake volumes increased from 7.06±1.27 km~3 to 13.08±2.09km~3,respectively,an increase of 85.27%.Until the end of this century,the potential glacial lake water reserves in the Karakorum region were the most dense,accounting for 92.58%(12.11±2.66 km~3)of the total potential glacial lake water volume of glacial lake contact glaciers in the study area,followed by the Eastern Himalayas and the Central Himalayas,accounting for 3.13%(0.41±0.07 km~3)and 2.68%(0.35±0.05 km~3)of the total potential glacial lake water volume in the region,respectively.In contrast,the western Himalayan section has the least amount of potential glacial lake water,accounting for only 1.61%(0.21±0.03 km~3)of the total potential glacial lake water of glacier-lake contact glaciers in the study area.Similar to the change in glacial lake area,the total potential glacial lake water resources in the region showed a significant increasing trend with an increase rate of about 0.02%a^-1 from 2050 to 2100.In addition,261(31.26%)of the existing glacier-contact glacial lakes will have the potential for continued expansion.By the end of this century,the total expansion area of glacial end-contact lakes with expansion potential is 11.41±1.71 km~2,accounting for 13.29%of the total potential glacial lake area in 2050 and 6.14%of the total potential glacial lake area in 2100.In addition,historical data(extent of expansion and depth)of a typical"very high"risk glacial lake,Longbasaba Lake,are analyzed to verify the reliability of the results of this paper for potential glacial lake predictions and to assess its hazards.Under future warming scenarios,rapid and feasible water management and storage options are needed as robust adaptation measures to deal with high uncertainty,high risk,and complex hydro-climatic and social intertwined environments.