We pump so much water out of the ground that we are killing our rivers – Life Unscripted
In the new analysis, de Graaf and her colleagues found that 15 to 21 percent of watersheds that pump groundwater are already past this threshold (about half of all watersheds worldwide are pumped). As climate change exacerbates droughts in many parts of the world, the stresses on groundwater—and by extension, on rivers and streams—is likely to get much, much worse, they say.
Their predictions might be conservative. As a baseline, they used the global water demand in 2010 and spun their climate model forward to see how stresses on groundwater systems might develop. But as populations swell and the demand for food rises, those stresses could increase for reasons other than climate change, speeding along the extraction from underground water sources.
But the effects of overpumping groundwater take years, if not decades, to become visible. Changes in rain have immediate, obvious effects on river flow, explains Gretchen Miller, a hydrologist and engineer at Texas AM University: When it pours, rivers often rage. But groundwater is hidden: changes take much longer to come to light, and don’t always manifest in the place where the pumping occurs. That makes aquifer management issues extra challenging, and only a small fraction of watersheds have plans in place to address the looming problems.
In the meantime, rivers and streams are the “canary in the coal mine,” says Richter. “They’re the signal that says we’re using water in an unsustainable fashion, we need to take a hard look at what we’re doing.”