Glacier retreat and its impact on groundwater system evolution in the Yarlung Zangbo source region, Tibetan Plateau

Study region: Jiemayangzong Glacier basin, source of the Yarlung Zangbo, Tibetan Plateau. Study focus: Mountain groundwater is an important water source to recharge rivers. However, there is still a lack of a suitable "climate-glacier-groundwater" modeling framework to project future changes of glacier and the consequent impacts on evolution of groundwater in the Tibetan Plateau (TP). The groundwater model HydroGeoSphere (HGS) is coupled with the glacier retreat method Delta h - parameterization to simulate subglacial meltwater recharge to groundwater (SMRG), precipitation recharge to groundwater (PRG), and total groundwater recharge (TGR) in the Jiemayangzong Glacier basin, source of the Yarlung Zangbo. New hydrological insights for the region:Results show that the volume of the Jiemayangzong Glacier would continuously retreat from 2021 to 2100. For the SSP126 and SSP585 climate change scenarios, the glacier volume would maximum decrease to 26.1% and 14.7% in 2100 (reference similar to 2021), respectively. The simulated rate of annual SMRG is 24 mm/yr, which accounts for 63% of TGR. SMRG and TGR would decrease to 26% and 73% in 2100 under SSP585 climate change scenarios. Although PRG would continuously increase to 151% for SSP585 in 2100, it could not counteract the loss of SMRG. The change in hydraulic head is significant in the glacier terminus and the aquifer shallow zones (elevation above 4000 m). Glacier retreat results from increasing temperature will seriously affect local groundwater resources, particularly for the SSP585 scenario.