The National Academy of Sciences conducted a workshop on research needs for remotely sensed data for groundwater flow and recharge on June 27-28 in Washington, D.C. The meeting was sponsored by the National Geospatial-Intelligence Agency.
Key points presented included:
- In areas of South Asia, too much groundwater has been applied to grow rice, leading to aquifer depletion and recognition of needed human decision data
- In California, land subsidence from groundwater use is partly related to pumping and partly to geology
- Deep sediments in offshore areas may hold 100,000 km3 of fresh groundwater with total dissolved solids less than 1,000 mg/L, but they would be expensive to develop
- InSAR measures ground deformation from space and combined with hydrologic data can give estimates of storativity
- GRACE and GRACE-FOLLOW-ON provide inventory of water bodies and watershed hydrology, including water extent, elevation, ground slope, and input for best estimates of baseflow
- Technology is needed for high resolution of smaller areas, mapping electrical resistivity of subsurface, and three-dimensional data
- Human factors affecting water use are a significant aspect in addressing uncertainty in modeling groundwater flow and abstraction.
Remote-sensing data research needs include:
- More irrigation water use data
- Decision-making associated with irrigation and other water uses
- The need for more detail due to the mismatch of scales — large areas with subsurface are remotely sensed by satellite but more detail is needed for site management
- Water quality data for human health protection
- Data on extremes of depth, drought, and flooding.
Potential applications include support for agricultural irrigation decisions, managed aquifer recharge, and addressing flood effects on the subsurface.