15 The Low Down on the High Plains: Geologic and Hydrogeologic Studies of the High Plains Aquifer

Tuesday, 26 March 2019
8:00 AM - 12:00 PM
Flint Hills Room

CHARACTERIZING AQUIFER PROPERTIES IN THE VICINITY OF A GROUNDWATER MOUND IN THE HIGH PLAINS AQUIFER, SOUTH-CENTRAL NEBRASKA

Paper number: 15-2
Program: Theme Sessions
Time: 8:20 AM – 8:40 AM

Authors

Abstract

Several irrigation canal systems were constructed over the High Plains aquifer prior to widespread groundwater pumping and have produced four large groundwater mounds in Nebraska. One of these mounds is located in part under Phelps and Kearney counties, where the lateral extent is more than 2,000 km2 and the maximum rise in the predevelopment water table is approximately 25 to 30 m. Elevated anthropogenic nitrate concentrations are widespread in Phelps County and also exceed 10 mg/L in parts of Kearney and Adams counties downgradient from the mound. Groundwater in this area is managed by two Natural Resources Districts using different regulations. The nitrate concentrations are high at depth in places, and aquifer heterogeneity further complicates management. Mapping aquifer properties using existing bore hole data indicates that: 1) the shape of the mound roughly matches the configuration of the canal system; 2) relatively thin (~3 m) but laterally extensive confining units exist within the aquifer; 3) gaps in these confining units may allow nitrate to reach deep parts of the aquifer; and 4) post-depositional deformation and erosion of the underlying Cretaceous surface and erosion on the Ogallala Group effect the transmissivity of the aquifer.

Geological Society of America Abstracts with Programs. Vol. 51, No. 2

doi: 10.1130/abs/2019SC-326319

© Copyright 2019 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.