Satellites measure recent rates of groundwater depletion in California's Central Valley

Here we use 78 months (October, 2003 - March, 2010) of data from the Gravity Recovery and Climate Experiment satellite mission to estimate water storage changes in California's Sacramento and San Joaquin River Basins.

We find that the basins are losing water at a rate of 31.0 ± 2.7 mm yr ⁻¹ equivalent water height, equal to a volume of 30.9 km 3 for the study period, or nearly the capacity of Lake Mead, the largest reservoir in the United States. We use additional observations and hydrological model information to determine that the majority of these losses are due to groundwater depletion in the Central Valley. Our results show that the Central Valley lost 20.4 ± 3.9 mm yr ⁻¹ of groundwater during the 78-month period, or 20.3 km ³ in volume.