Groundwater Rise Sustains the World's Largest Alpine Water System Under Global Warming

Area of Science:

• Hydrology
• Ecology
• Climate Science

Background:

• The Qinghai-Xizang Plateau (QXP), known as the

Purpose of the Study:

• To assess shallow groundwater dynamics on the QXP's non-permafrost plains.
• To investigate the impact of groundwater changes on alpine ecosystems.
• To evaluate the QXP's freshwater storage capacity and potential for climate adaptation.

Main Methods:

• Integration of over 8000 in-situ groundwater records.
• Utilization of multi-source remote sensing data.
• Analysis of groundwater depth trends, capillary rise, and Normalized Difference Vegetation Index (NDVI).

Main Results:

• Shallow groundwater depth decreased by 0.02 m/year from 2000-2020, indicating a net freshwater storage gain of approximately 31.44 Gt.
• Groundwater rise sustains ~53,500 km² of alpine ecosystems and correlates with increased NDVI in groundwater-dependent vegetation.
• The vadose zone has an estimated remaining storage capacity of 426.6 Gt, suggesting potential for managed underground reservoirs.

Conclusions:

• QXP's shallow aquifers act as a dynamic, growing freshwater reservoir, contradicting widespread water loss narratives.
• Groundwater dynamics are crucial for understanding alpine ecosystem changes and potential regime shifts.
• The QXP's water system may possess greater resilience to global warming than previously assumed, challenging surface-water-centric vulnerability assessments.