In parts of California’s Central Valley, so much groundwater has been pumped out of the ground to deal with the region’s persistent drought that the land is starting to sink in. Underground aquifers — layers of sand, gravel, clay, and water — are vital resources that communities can turn to when surface water is scarce. But when more water is pumped out of aquifers than is put back in — as is happening in the southern part of the valley — it can cause the ground to slowly contract, like a drying sponge. CONTINUE READING