Kansas Geological Survey, Open-file Report 2012-2
Part of the Ogallala-High Plains Aquifer Project

High Plains Aquifer Calibration Monitoring Well Program: Fifth Year Progress Report

by
J. J. Butler, Jr., R. L. Stotler, D. O. Whittemore, E. Reboulet, G. C. Bohling, and B. B. Wilson
with contributions by J. Munson, D. Means, and S. Ross

KGS Open File Report 2012-2
March 2012

Executive Summary

The index well program is directed at developing improved approaches for measuring and interpreting hydrologic responses at the local (section to township) scale in the High Plains aquifer (HPA) in western Kansas. The study is supported by the Kansas Water Office (KWO) with Water Plan funding as a result of KWO's interest in and responsibility for long-term planning of ground-water resources in western Kansas. The Kansas Department of Agriculture, Division of Water Resources (DWR), is providing assistance, as are Groundwater Management Districts (GMDs) 1, 3, and 4.

The project began with the installation of three transducer-equipped wells, designed and sited to function as local monitoring wells, in late summer 2007. One of these index wells is installed in each of the three western GMDs, with locations deliberately chosen to represent different water use and hydrogeologic conditions, and to take advantage of related past or current studies. A major focus of the program has been the development of criteria or methods to evaluate the effectiveness of management strategies at the subunit (e.g., township) scale. Changes in water level--or the rate at which the water level is changing--are considered the most direct and unequivocal measure of the impact of management strategies. At the time of this report, monitoring data (hourly frequency) from four full recovery and pumping seasons and one ongoing recovery season have been obtained at the three index wells; additional water-level data have been obtained from wells in the vicinity of two of the index well sites.

This report provides (a) an update of the hydrographs for the three index wells; (b) interpretation of hydrographs from the index wells and the wells in the expanded monitoring areas in the vicinity of two of the index wells; (c) a discussion of the expanded monitoring that has resulted from the findings of the index well program; (d) a discussion of the sampling and geochemical analysis of water from the three index wells and from four irrigation wells near one of the index wells; and (e) the final version of the KGS barometric correction spreadsheet program, which calculates the barometric response function for a given well and corrects the measured water levels for the impact of barometric pressure changes. A particular emphasis of this report is on the important new insights that have been obtained from the interpretation of hydrographs from the index wells and from wells in the expanded monitoring areas in the vicinity of two of the index wells.

The major findings of the project are as follows:

Water-level data collected using a pressure transducer and data logger provide a near-continuous record of great practical value that can help in the assessment of the continued viability of the HPA as a source of water for large-scale irrigation.
The data from the index wells provide the critical context needed for improved interpretation of the results of the annual measurement program.
Hydrographs from the index wells and associated monitoring wells can be analyzed using methods developed for the interpretation of pumping tests to obtain insights into the primary mechanisms controlling the changes in water level in those portions of the HPA. An understanding of these mechanisms is critical for reliable assessment of what the future holds for the HPA in western Kansas.
A detailed examination of the hydrographs from the Haskell County index well and DWR-monitored wells in that vicinity reveals that, despite the relatively thick saturated interval, it is likely that large-scale irrigation withdrawals will not be sustainable beyond the current decade in the vicinity of the Haskell site, except, possibly, in those wells that are also completed in the discontinuous sandstones of the underlying Dakota Formation.
A detailed examination of the hydrographs from the Thomas County index well and nearby wells monitored with the assistance of DWR and GMD4 reveals that a significant amount of water flows into the HPA in that vicinity. This inflow, which is revealed by the near-coincidence of recovery rates between years, is independent of conditions in the previous pumping season (e.g., duration, withdrawals, and precipitation). Determination of the origins of this inflow at the Thomas County index well is critical for assessing the continued viability of that portion of the HPA as a water source for irrigated agriculture.
Hydrograph patterns observed at the Thomas County index well were also discerned in shorter-term hydrographs from two wells in Sheridan and northwestern Thomas counties, indicating that such inflow is likely also occurring in those areas.
A detailed examination of the hydrograph from the Scott County index well reveals that inflow independent of conditions in the previous pumping season is also affecting water levels during recovery periods at that well. Further data, however, are needed before more conclusive statements can be made.

The focus of project activities in 2012 will be on the continuation of the detailed analyses of hydrographs from the project wells, expansion of the monitoring in the vicinity of the Scott County index well, cooperation with GMD4 on the interpretation of water-level data from monitoring wells in the Sheridan-6 subunit, further interpretation of geochemical results of analyses of water samples from the vicinity of the index wells, and an assessment of the contribution of the Dakota aquifer to pumping withdrawals in the vicinity of the Haskell County index well.

The complete text of this report is available as an Adobe Acrobat PDF file.

Read the PDF version (10.3 MB, May 2, 2012)

Kansas Geological Survey, Geohydrology
Placed online May 2, 2012
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