Observed Glaciohydrological Changes in China's Typical Monsoonal Temperate Glacier Region since 1980s

Under the background of significant climate warming since the 1980s, the glaciers in China＇s monsoonal temperate glacier region respond to the warming intensely. Based on the glaciohydrological observations at some typical glaciers from Mts. Yulong （玉龙） and Gongga （贡嘎） of Hengduan （横断） Mountains Range in the southeastern Tibetan plateau, the glaciohydrological changes in the temperate glacier region since the 1980s were investigated. First, the glacier terminus exhibited an accelerating retreat. Second, as the glacier area subject to melting has increased and the ablation season has become longer due to the warming, the ablation of glacier enhanced, leading to increasing contribution of meltwater to annual river discharge. Third, surface topography of small temperate glacier may be changed significantly by crevasses and ruptures developed in the accumulation zone and ice collapse events in the ablation zone. The observed results may indicate a signal that the survival of glaciers in China＇s monsoonal temperate glacier region is being threatened by today＇s climate warming.

Linking basin-scale hydrology with climatic parameters in western Himalaya:Application of satellite data,temperature index modelling and in-situ observations

Due to limited spatial and temporal in-situ runoff data availability,Himalaya-Karakoram(HK)glaciohydrology has a significant knowledge gap between large-scale and small-scale runoff modelling studies.This study reconstructs longest basin-wide runoff series in Chandra-Bhaga Basin by applying a high-resolution glaciohydrological model SPHY(Spatial Processes in Hydrology)over 1950–2022.Two-tier model calibration is done using in-situ basin-wide runoff(1973–2006)and MODIS snow cover(2003–2018).Model validation is done against in-situ Chhota Shigri Glacier catchment-wide runoff(2010–2015).The modelled mean annual basin-wide runoff is 60.21±6.17 m^(3)/s over 1950–2022,with maximum runoff in summer-monsoon months,peaking in July(182.69 m^(3)/s).Glacier runoff(ice melt+snowmelt over glacier)contributes maximum(39%)followed by equal contributions from snowmelt runoff from non-glacierized basin area and baseflow(25%),while rainfall-runoff contributes minimum(11%)to total runoff.There is a significant volumetric increase by∼7%from pre-(59.17 m^(3)/s)to post-2000(63.47 m^(3)/s)mainly because of early onset of snowmelt post-2000 that resulted in a hydrograph shift by∼25 days earlier in spring.The glacier runoff is overestimated by 3%from RGI 7.0 inventory compared to different manually delineated inventories over 1950–2022,because of higher glacierized area from RGI 7.0.The precipitation shows a negative trend,but total runoff shows a positive trend due to positive trend of temperature that resulted in more glacier runoff and rainfall-runoff for basin over last 72 years.Basin-wide runoff is mainly governed by summer temperature which directly controls the amount of glacier and snowmelt runoffs and is supported by summer rainfall.This study highlights importance of basin-scale model calibration with in-situ data in large scale studies and stresses the need for in-situ observations in high-altitude Himalayan region.Basin-scale calibrated model parameters are transferable to glacier catchment scale within Chandra-Bhaga Basin,showing the model robustness at a small catchment scale.