Natural Resources, School of

 

Date of this Version

2019

Citation

Korus, J.T. and Howard, L.M., Maps showing the Physical Hydrogeology and Changes in Saturated Thickness (Predevelopment to Spring 2016 and Spring 2011 to Spring 2016) in the Middle Republican Natural Resources District, Southwestern Nebraska. University of Nebraska-Lincoln, Conservation and Survey Division, Nebraska Resource Atlas Number 12, 16 pp. and 14 plates.

Comments

RA-12 publication with maps and GIS data

Abstract

This report accompanies fourteen new maps summarizing the hydrogeology and changes in saturated thickness in the Middle Republican Natural Resources District (MRNRD). The purpose of these maps is to assist the MRNRD in their groundwater management programs and in planning and installing an observation well network. Maps include:

• base of the principal aquifer;

• water table surfaces for predevelopment, Spring 2011, and Spring 2016;

• saturated thicknesses for predevelopment, Spring 2011, and Spring 2016;

• changes in saturated thickness (both in absolute magnitude and in percent) from predevelopment to Spring 2016 and from Spring 2011 to Spring 2016;

• transmissivity.

A series of comprehensive datasets was assembled from borehole logs and groundwater-level measurements. Borehole logs were assessed for quality using systematic procedures. Maps were generated using ordinary kriging (base of aquifer, transmissivity) and co-kriging (water table surfaces), and raster files were subtracted to derive the saturated thickness and change maps. Saturated thickness decreased as much as 35 ft from predevelopment to 2016, and as much as 10 ft from 2011 to 2016. Percentage decreases were as much as 40% from predevelopment to 2016 and as much as 10% from 2011 to 2016. Increases in saturated thickness occurred near surface water development projects north of the MRNRD, and were as much as 36 ft (15%) from predevelopment to 2016. Increases from 2011 to 2016 occurred in a few small areas, and were as much as 3 ft (5%). The calculated change in saturated thickness was highly variable between the two time periods in areas of sparse data and where the aquifer is thin. Digital GIS files are provided as part of this report for use in models, maps, and related hydrogeologic analyses.

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