The Nepal Himalayas supply essential water resources to a large part of the population of South Asia. Most of this water drains through a mountain groundwater reservoir. Understanding how the reservoir fills and drains is crucial to the assessment of freshwater resources and make predictions for the future with respect to global climate change. However, groundwater processes are generally challenging to observe due to limited access to the subsurface, particularly in steep mountain landscapes.
Illien et al.  use seismic ambient noise, namely, ground vibrations continuously recorded by seismometers, to monitor the groundwater dynamics within an Himalayan valley. The findings shed new light on the mechanisms governing the water towers of Himalaya. In particular, they show that a key role is played by the thickness and properties of the soil and regolith layer, which is a gate keeper to the fractured crystalline bedrock in which the groundwater reservoir is primarily located.
Citation: Illien, L., Andermann, C., Sens-Schönfelder et al. . Subsurface moisture regulates Himalayan groundwater storage and discharge. AGU Advances, 2, e2021AV000398. https://doi.org/10.1029/2021AV000398
—Alberto Montanari, Editor, AGU Advances