Unsaturated-Zone Study - Ogallala Formation, northern High Plains
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Boreholes were drilled at one site in Chase County, Nebraska, at which
rangeland was the dominant land use, and at two sites in Yuma County, Colorado and Perkins County, Nebraksa, at which
irrigated agriculture was the dominant land use. Sediment cuttings and cores were collected
during drilling for the analysis of physical properties (particle size, bulk density, porosity,
gravimetric and volumetric water contents, and matric potentials) and chemical concentrations
(tritium, chloride, nitrate, and six pesticides and two pesticide degradates). The
boreholes were instrumented with monitoring wells and pressure transducers to measure
ground-water elevations, advanced tensiometers (AT’s) and heat-dissipation probes (HDP’s) to
measure soil-water matric potentials, suction lysimeters were installed in the unsaturated
zone to collect soil-water samples, and ground-water samples were collected from the
monitoring wells. Soil water collected in 2003 was analyzed for chloride, nitrate, and
atrazine. Ground water collected in 2002–2003 was analyzed for tritium, chloride, nitrate, and
47 pesticides and pesticide degradates. Water potentials and profiles of tritium, chloride, nitrate, and pesticide
concentrations were used to evaluate water movement through thick unsaturated zones overlying
the central High Plains aquifer.
(journal abstract).
Figure 1 shows the location of the wells. Click below to retrieve the entire data set of selected water-quality data (only data analyzed by the National Water-Quality Laboratory).
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U.S. Department of the Interior | U.S. Geological Survey
Page URL: http://co.water.usgs.gov/nawqa/hpgw/datarep/unsat3/UNSAT3.html
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Page Last Modified: Friday, 16-Feb-2007 18:12:00 EST
