NASA satellites are returning some disturbing news about the state of the earth’s groundwater. Two GRACE (Gravity Recovery and Climate Experiment) satellites are reporting data based on small monthly changes in Earth’s gravity field that are chiefly caused by water movement across the Earth’s water stores. The two GRACE satellites are the only satellites capable of monitoring deep stores of water in the earth.
According to Grace readings, the Sacramento and San Joaquin drainage basins have lost over 30 cubic km of water since 2003, mostly due to agricultural use in the Central Valley of California. The San Joaquin and Sacramento Basins are losing approximately 3.5 and 2 cubic km of water per year, respectively.
“Grace data reveal groundwater in these basins is being pumped for irrigation at rates that are not sustainable if current trends continue,’ Famiglietti said. ‘This is leading to declining water tables, water shortages, decreasing crop sizes and continued land subsidence. The findings have major implications for the U.S. economy, as California’s Central Valley is home to one sixth of all U.S. irrigated land, and the state leads the nation in agricultural production and exports.” – Professor Jay Famiglietti, UC Irvine
GRACE satellites were spot on in tracking the southeast U.S. drought over the past few years and are currently monitoring groundwater around the world. Other recent findings include evidence that groundwater in northern India is declining by up to 1 foot per year since 2000.
All of this groundwater loss is attributed to human use, whether for domestic or agricultural use.
Currently, NASA is teaming up with the National Oceanic and Atmospheric Administration (NOAA ) and the University of Nebraska-Lincoln to work satellite data into U.S. and North American Drought Monitors for use as part of drought monitoring, analysis and impact management.