Monday, March 18, 2013

Underground water levels in high plains shrinking

Threatened by another summer of crop-shriveling drought, Kansans have agreed to across-the-board cuts in water use. In the 100 square-mile “high priority” (meaning particularly parched) zone of Northwest Kansas, Groundwater District 4 reached a consensus to reduce groundwater pumping by 20 percent over the next five years, writes Jim Malewitz of Stateline.

He writes that Kansans are gambling on short-term wants for a longer-term need — to preserve the aquifer their lives depend upon. The plan is just one of many major efforts to fend off a slow-moving disaster with national implications: The High Plains Aquifer, which feeds some of the world’s most productive croplands, is running dry.

The aquifer, also called the Ogallala, is one of the world’s largest underground sources of freshwater, he writes. It stretches 174,000 square miles through the middle of the country from South Dakota to northwest Texas, touching six states, watering more than one-quarter of all irrigated acreage in the U.S. and some of world’s largest grain cattle feedlots. The Ogallala also provides drinking water to four of every five people living above it.

Since Americans first began to seriously irrigate the Great Plains, beginning in the 1940s, water levels across most of the Ogallala have fallen at least five feet, according to the U.S. Geological Survey. Almost one-fifth of the area has dropped at least 25 feet, while 11 percent has lost 50 feet or more. In some of the worst-off areas of Kansas and Texas, the water table has declined as much as 200 feet. The most recent drought has compounded the problem, drying up riverbeds and forcing farmers to rely even more heavily on groundwater.

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