The groundwater subsidy – what happens to it after we pump it up and use it – is frequently ignored in policy discussions. When we stop mining groundwater, I’ve often argued, we need to recognize that the share we discharge into our rivers, which becomes water supply to those downstream, goes away.
But via David Appell, here’s a role groundwater pumping plays that I’d never considered – sea level rise:
Groundwater depletion has more than doubled during the last decades, primarily due to increase in water demand, while the increase in water impoundments behind dams has been tapering off since the 1990s. As a result, the contribution of groundwater depletion to sea-level rise is likely to dominate over those of other terrestrial water sources in the coming decades.
That’s from Wada et al, Past and future contribution of global groundwater depletion to sea-level rise, GEOPHYSICAL RESEARCH LETTERS, VOL. 39, L09402, 6 PP., 2012 doi:10.1029/2012GL051230