Linking Groundwater Quality and Quantity: An Assessment of Satellite-Based Groundwater Storage Anomalies From GRACE Against Ground Measurements of Contaminants in California

Groundwater comprises a large portion of irrigation for California's agriculture, and sustains a wide diversity of ecosystems as well as consumptive use, but pumping is occurring faster than replenishment. At the same time, contaminants from fertilizers and pesticides are infiltrating into the groundwater, becoming increasingly concentrated as water is extracted. We compared space-based observations of groundwater anomalies from California's San Joaquin Valley using the Gravity Recovery and Climate Experiment (GRACE) against measurements of 42 organic and inorganic chemicals from 41,667 wells in the valley from 2003 to 2010. Preliminary results show both strong and weak correlations with groundwater depletion against increasing chlorine (r2=0.78), boron (r2=0.88), but no relationship with benzene (r2=0.03). These results are the first to link space-based groundwater quantity with groundwater quality.