The High Plains aquifer accounts for nearly 30% of all groundwater withdrawals in the United States. The aquifer is under increasing developmental stress and experiencing historic declines in water levels that could seriously compromise major agricultural production on the North American Great Plains. The objective of this research is to investigate the subsurface sedimentary facies, stratigraphic framework, and chronostratigraphy of Neogene and overlying Quaternary units in the central High Plains aquifer. These properties control aquifer geometries and hydrogeologic relationships and are derived from the formative processes and depositional histories of water-bearing and confining strata. Quality stratigraphic information from the High Plains, however, has been impossible to retrieve previously due to unconsolidated and saturated intervals of the aquifer. To accomplish this, PIs will use a mobile platform-mounted rotary-vibratory drill rig. This state-of-the-art drilling technology provides, for the first time, an efficient and cost effective means of collecting intact core with nearly 100% recovery. Long continuous cores, coupled with lithologic, spectral gamma-ray, and magnetostratigraphic core logging; stable isotope chemostratigraphy; and geochronologic constraints imposed by tephrochronologic, optically stimulated luminescence (OSL), magnetic polarity studies, and U/Pb dating of Neogene sediments, will provide the critical time element to constrain permissible interpretations of stratigraphic correlation and hydrostratigraphic architectures.
This research will have global import because aquifers in heterolithic successions of continentally derived Neogene sediments are under developmental stress in many parts of the world. Management of groundwater resource is achieved most effectively by using numerical modeling to predict hydrogeological response to different management strategies and such models depend on accurate characterization of aquifer materials and their stratigraphic framework.
