Mountain groundwater monitoring with seismic ambient noise: what to do next ?

There is a growing understanding that groundwater has an important volume in mountainous areas,  controlling hydrological budgets and fluxes towards lowland basins. However, the observation of this reservoir is challenging, with less boreholes in steep and remote catchments. In the last decade, attempts to monitor groundwater via seismic waves velocity monitoring (a technique called seismic interferometry) have emerged, opening interesting avenues for mountain hydrology. Indeed, the deployment of seismic stations at high elevation is logistically more feasible and offers a good proxy for subsurface water. Here, I present three seismic deployment campaigns, aimed at monitoring groundwater dynamics in different mountainous conditions. These studies are located in 1. A catchment in the Nepal Himalayas 2. On a steep ridge in Taiwan and 3. In Alpine conditions in Switzerland.  Suggestions for calibrating the method and going from seismic velocity changes to groundwater volumes are discussed with the hope to build more bridges between seismologists and mountain hydrogeologists.