A new satellite-based study has revealed a worrying decline in groundwater reserves across High Mountain Asia, a vast region often called the “Asian Water Tower” because it supplies water to hundreds of millions of people downstream. Researchers estimate that the region is losing groundwater at an alarming rate of nearly 24.2 billion tonnes every year, raising concerns about long-term water security.
High Mountain Asia stretches across the Himalayas, Karakoram, Hindu Kush and Tibetan Plateau, feeding major rivers such as the Ganges, Indus, Brahmaputra and Amu Darya. These rivers support agriculture, cities and ecosystems across more than a dozen countries in South and Central Asia.
Two decades of data show widespread decline
The study, led by Professor Wang Shudong of the Chinese Academy of Sciences, analysed satellite observations from 2003 to 2020 using an advanced artificial intelligence model. The findings show that nearly two-thirds of the region experienced declining groundwater storage over this period.
The sharpest losses were recorded in densely populated and heavily irrigated downstream basins, including the Ganges–Brahmaputra, Indus and Amu Darya river systems. In contrast, some high-altitude inland areas showed limited and localised recovery, offering little relief to water-stressed regions further downstream.
Researchers found that climate-related factors, including snowfall, rainfall and glacier dynamics, explained almost half of the changes in groundwater levels. However, human activities especially groundwater extraction for irrigation have become an increasingly dominant driver of depletion, particularly after 2010.
AI-powered satellites uncover hidden risks
To overcome the challenge of limited ground data and complex mountain terrain, scientists developed a new AI-based assessment framework. The system combined multi-sensor satellite data, Earth system modelling and explainable machine learning to reconstruct groundwater trends and identify their underlying causes.
The model was validated using thousands of groundwater well measurements, making the findings among the most comprehensive assessments of groundwater sustainability in High Mountain Asia to date. According to the researchers, the approach offers a reliable way to monitor water resources in regions where traditional measurements are sparse or inaccessible.
Future outlook raises serious concerns
Looking ahead, the study warns that groundwater depletion is likely to continue if current water-use practices remain unchanged. While glacier melt may temporarily slow groundwater loss in some areas around the 2060s, this effect is expected to be short-lived.
Once glacier reserves decline further, groundwater losses could accelerate, putting downstream agricultural zones and water-dependent communities at even greater risk. The researchers stress that urgent action is needed to manage groundwater extraction and strengthen water governance across the region.
The study was published in the journal Environmental Research Letters and adds to growing evidence that Asia’s most critical water source is under increasing pressure from both climate change and human demand.