US: Data from NASA's Gravity Recovery and Climate Experiment, or GRACE, satellites reveals that about 30 percent of Earth's largest groundwater basins are in distress. GRACE measures dips and bumps in Earth's gravity, which are affected by the mass of water. Despite its importance, knowledge on the state of groundwater systems is limited as compared to surface water. This is largely because the cost and complexity of monitoring large aquifer systems is often prohibitive. Never mind that groundwater is the primary source of freshwater for about two billion people. According to Jay Famiglietti, senior water scientist at NASA's Jet Propulsion Laboratory in California, available physical and chemical measurements are simply insufficient. We need a coordinated global effort to determine how much groundwater is actually left. The research team says that the Arabian Aquifer System, which is a water source to more than 60 million people, is the most overstressed in the world.
Source: Washington Post