U.S. Water News Online
LINCOLN, Neb. -- According to a University of Nebraska-Lincoln (UNL) research hydrogeologist, a massive groundwater aquifer lies beneath Nebraska's Sandhills in the western part of the state -- and it's intimately connected to the vast expanse of sand which stretches over this section of the Great Plains.
Darryll Pederson, geology professor with UNL's Conservation and Survey Division, recently presented his findings in a report titled,Interrelationship of High Plains aquifer thickness, sand fields, rivers and groundwater.
"You look at the Sandhills and see sand, but that's just the 'skin' on top of an abundant water supply," Pederson said. The Sandhills and much of Nebraska rest above the High Plains (Ogallala) aquifer, a massive groundwater reservoir stretching from Wyoming and South Dakota to western Texas and eastern New Mexico.
In the entire High Plains aquifer, the place where the water is deepest is beneath the Sandhills.
The key to that water volume, and to Pederson's work in this area, is that sand is highly permeable; water flows through it easily.
"Naturally, where water can seep down more easily you have a higher potential for great aquifer thickness," said Pederson. "You can't have an aquifer without some degree of permeability."
The Sandhills also have abundant sand and gravel deposits, which hold a great deal of groundwater. The result is a perfect blend of surface recharge and adequate underground storage. The aquifer is estimated to be more than 1,000 feet thick in parts of the Sandhills, Pederson said, compared with an average of 100 feet in areas with less sandy and less permeable soils.
Aquifer formation is just one of the sand's many effects in the Sandhills, said Pederson, who explained that the permeability of this sandy region limits surface runoff which would otherwise erode the land, forming permanent stream channels.
Heavy precipitation or massive snowmelt from the Rocky Mountains are the only events that could provide such water volume, he said, adding that the Platte River is a perfect example of a river system that was supplied enough water to "downcut," or establish a permanent channel.
There is little question that the sand in the Sandhills is here to stay, according to Pederson. Because Nebraska sits just east of snow-capped mountains, and with drainage patterns of the North and South Platte rivers and the tendency of rivers to drop sediments on existing deposits, the Sandhills are a perfect example of a self-maintaining sand sea.
"Everything is in balance," he said. "The Sandhills are in just the right place to demonstrate these concepts," he said.
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