Remote Sensing of Groundwater: Current Capabilities and Future Directions

Globally, groundwater represents a critical natural resource that is affected by changes in natural supply and renewal, as well as by increasing human demand and consumption. However, despite its critical role, groundwater is difficult to accurately quantify as it is beneath the Earth surface. Here, we review several state-of-the-art remote sensing techniques useful for local- to global-scale groundwater monitoring and assessment, including proxies for groundwater extraction. These include inferring changes in subsurface water from mass changes using gravitational measurements, and analyzing changes in the Earth surface height using Interferometric Synthetic Aperture Radar, Light Detection and Ranging, Airborne Electromagnetic Systems, and satellite altimetry. Remote sensing information is often used in tandem with ground-based observations such as hydraulic head in wells, Global Navigational Satellite System monitoring, and numerical modeling to complement the space-based approaches. In the future, fusing different remote sensing techniques capable of operating in various environments will yield additional insight on the state and rate of use for groundwater across the globe.