Scientists have produced a new method that holds the promise of improving groundwater management – critical to both life and agriculture in dry regions. The method sorts out how much underground water loss comes from aquifers confined in clay, which can be drained so dry that they will not recover, and how much comes from soil that’s not confined in an aquifer, which can be replenished by a few years of normal rains.

The research team studied California’s Tulare Basin, part of the Central Valley. The team found that the key to distinguishing between these underground sources of water relates to patterns of sinking and rising ground levels in this heavily irrigated agricultural region.