Approximately 200 miles above the Earth’s surface, two satellites circle the planet together, measuring and sending data about changes of many things. The satellites are referred to as Grace, (Gravity Recovery and Climate Experiment). While they live in space, they’re providing invaluable assistance in managing one of our natural resources on the ground, groundwater.
GRACE has created a unique picture of groundwater storage level changes over the past 11 years. This information already is helping water users and policymakers manage scarce groundwater resources in California, the Tigris-Euphrates Basin and several other locations around the world. It’s also providing an example of how satellites and remote sensing are reshaping the water world, opening new frontiers for water resources management and making remarkable progress in spotlighting global water risks.
According to the U.S. Geological Survey (USGS), approximately 26 percent of the freshwater withdrawn in the United States every day comes from groundwater. That number varies in different regions and countries, but groundwater-storing aquifers are an important source of drinking water and a primary buffer against drought around the world, offering more stable supplies when surface sources such as lakes and reservoirs are depleted. But in many parts of the world, little or no information is publicly available on how much water a given aquifer contains. It’s rare to know how much water people are withdrawing or how this relates to replenishment rates.
Even in a developed state such as California, land owners can pump underground water without any reporting or metering. The specifics, of course, change around the world, but ignorance of groundwater levels and sustainable withdrawal rates is the common denominator.
That’s where GRACE comes in.
As the two satellites orbit the earth, they provide transparent but necessary data that can make up for the lack of on-the-ground monitoring of water resources around the world.
At times, some countries have refused to release their water-related data, citing security concerns, but the GRACE remote-sensing technology has created a bypass around the reluctance of many countries to release their data providing us with greater precision mapping and understanding.
River basins must be managed efficiently, equitably and sustainably which is not possible without data. The goal of all this is to create leverage for water managers and for politicians to hopefully start acting on the best management solution for groundwater. Thanks Grace.