News Release, Kansas Geological Survey, Oct. 25, 2010
LAWRENCE--University of Kansas research will help Kansans sustain the state's precious water resources.
Scientists from the Kansas Geological Survey will map the depths of the Central High Plains Aquifer for the first time, thanks to a $381,000 grant from the National Science Foundation and a specialized drill rig. The aquifer--an underground layer of rock and sediment--supplies 70 percent of the water used in Kansas. The work will help determine how quickly wells may run dry in some areas and what effect different management strategies will have on conserving the remaining ground water. Drilling at seven sites in southwestern Kansas will begin within the next few months.
"We're really excited, because we will be able to examine the materials that make up the aquifer, look at how they're layered and how they're interacting with each other hydrologically," said Jon J. Smith, assistant scientist at the Kansas Geological Survey and principal investigator of the project. "That will in turn provide information for people modeling the behavior of the ground water and on how we can manage this resource for the future."
The massive aquifer supplies 30 percent of the irrigation water for the entire country and underlies portions of eight Midwestern states. Many stakeholders, including the Kansas Water Office and the state's groundwater management districts helped get the exploratory project moving, Smith said. Collaborating with Smith are Kansas Geological Survey associate scientist Greg Ludvigson and senior scientific fellow John Doveton.
What concerns many is that in some regions of Kansas and other states, the water table has dropped precipitously during the past 60 years--in some parts, nearly 200 feet. Since the 1940s, hundreds of thousands of wells have been drilled into the aquifer, providing water for agriculture, residential areas and industry.
"If it wasn't for the High Plains Aquifer there wouldn't be nearly the number of people or level of agricultural development in Kansas we see today, especially in the western portions of the state," Smith said.
Knowing how rocks are layered in a region can help predict which areas are most likely to dry up. Well drillers do try to document the layers they drill through. But the soggy bands mix when a rotary drill pushes them above ground.
To avoid that, the Kansas Geological Survey's rig carefully vibrates a yard-long, two-inch-diameter metal pipe into the ground to collect core of sediment. Water pressure keeps its contents from spilling. After pulling up each pipe the drill angles and the core sample slides into a transparent plastic tube for safekeeping. The Kansas Geological Survey is the only survey in the Midwest that has such a rig and will be the first to do this type of analysis on the aquifer, Smith said. The layers, including the water within them, will be analyzed and curated at the survey for further research. The cores that the team collects will tell the story of one 45-mile section in the formation--as far down as 400 feet and as far back as 23 million years.
About 23 million years ago, the uplifting Rocky Mountains began to shed sand, silt, clay and rock onto the High Plains.
"They weren't High Plains then," Smith said. "They were a series of deep valleys that were carved into older rocks. As the Rocky Mountains grew, they shed sediments to the east that initially filled the valleys. Eventually, these deposits overtopped the valley walls and formed a blanket of sediment covering most of the western Great Plains. It created that classic flat Kansan landscape that you see as you drive out west."
The flat landscape hides the aquifer, also known as the Ogallala Formation. Some of the layers contain millions-year-old rain that fell when the Midwest was more humid. Today's drier climate means that some of the water being pumped can't be replaced. Especially vulnerable are places where water is trapped between impermeable layers and can't be replenished from rainfall or from other regions in the aquifer.
"If we're drilling to a certain depth, are we tapping into a reservoir of water that's not very extensive?" Smith said. "Should all the water users in the area be drawing water from that same unit? The big problem is, right now it's almost a complete mystery. As scientists, we can't make those kinds of policy decisions. If there are changes that need to be made in the management of these resources, however, they should be made based on the best information possible and that's what we are hoping to provide."