News Release, Kansas Geological Survey, April 21, 2000
LAWRENCE--How fast do pesticides, nitrates, and other contaminants move from the surface into the Ogallala aquifer in western Kansas?
Water researchers from the Kansas Geological Survey, based at the University of Kansas, are working with scientists from the U.S. Geological Survey, Kansas State University's Department of Agronomy, and the Idaho National Engineering and Environmental Laboratory to try to answer that question.
The results could reveal much about the movement of water from the earth's surface into the Ogallala, and the impact of farming and other human activities on water quality. The Ogallala aquifer is a geologic formation composed of sand and gravel that underlies much of the western third of Kansas and is the source of most of the area's groundwater.
Three wells, drilled down to the Ogallala by the U.S. Geological Survey in March and April, will be the focus of the research. Two of the wells were drilled in southern Finney County, in locations adjacent to irrigated fields, and one was drilled in the Cimarron National Grasslands in Morton County.
Each well was drilled to about two-hundred feet, and core samples of the soil, sand, gravels, and other unconsolidated materials were brought back up to the surface. The samples will be analyzed to determine how easily water could move through them. They are also being analyzed for nitrate, ammonium, sulfate, chloride, pesticides, and other contaminants.
The results should tell researchers the amount of each contaminant that is found in various depths underground.
In addition, each well was outfitted with state-of-the-art instruments designed to measure the movement of water down through this unsaturated zone. Inside the borehole of each well, the scientists installed packages of sensors at different depths. The borehole was then refilled and the well casing removed. The sensors will measure the movement of water; other instruments will produce water samples that can be analyzed for contaminants.
"This should also tell us how quickly, and in what amounts, contaminants reach the Ogallala water table," said Survey geohydrologist Marios Sophocleous.
The results should also provide information about the rate at which water replenishes, or "recharges," the Ogallala. Information about recharge is relatively rare, although results indicate that recharge in western Kansas is probably limited to less than an inch per year in many places, mostly because water evaporates or is transpired by plants before it can move underground and eventually reach the water table.
"The results of this work should help us get a handle on the rate at which water moves down through the unsaturated zone and into the water table," said Sophocleous.
According to Sophocleous, the wells in Finney County should provide researchers with information about the movement of water in areas where crops are regularly grown. Those results can then be compared to the well in Morton County, which is predominately in grass and should not be affected by farming practices.
"These wells should tell us the amount and chemical make-up of water reaching the Ogallala in both irrigated and relatively pristine conditions," said Sophocleous.
The researchers plan to return to the western Kansas wells for additional work in May, and will take water samples from the wells soon after that. Story by Rex Buchanan (785-864-2601) For more information, contact Marios Sophocleous (785-864-2113)