Marco Janssen writes:

New Scientist of September 23 contains an interesting perspective on increasing the resilience to water shortages:

Draining reservoirs may not sound like the best solution to water shortages, but in parts of the US it may be the only answer. Overuse of underground water in states such as Kansas and New Mexico is causing aquifers to empty at alarming rates. Similar overuse of reservoirs combined with the earlier springtime melting of snow packs, caused by global warming, is shrinking them too.

So how best to make use of the dwindling supplies? Refilling the aquifers may provide a solution by avoiding the evaporation that takes place from reservoirs, according to Tom Brikowski of the University of Texas at Dallas. He told delegates at a meeting of the Geological Society of America in Longmont, Colorado, on Monday that slowly releasing some reservoir water can allow it to soak into the river bed downstream, refilling the aquifers beneath.

Brikowski studied the town of Hays, Kansas, which loses 75 per cent of its water supply, stored in the nearby Grand Bluffs reservoir, to evaporation. Using a computer model of the subsurface sand and gravel, he showed that releasing reservoir water would recharge the local aquifer and ensure that the town would have enough water to survive any repeat of past droughts. “This is a radical new way of thinking about how we manage our water, but we have no choice,” Brikowski says. “Kansas is at the forefront of this problem. As climate change continues, the rest of the West will experience it as well.”