Project ID: 2004NE78B

Title: Hydrogeological Controls of Salinity Patterns in the Sand Hills Lakes, NE

Project Type: Research

Focus Categories: Surface Water, Groundwater, Solute Transport

Keywords: lakes, salinity, hydrogeology, surface-groundwater relationships, the Sand Hills, aquifer characterization, field methods

Start Date: 03/01/2004

End Date: 02/28/2005

Federal Funds: $19,975

Non-Federal Matching Funds: $45,389

Congressional District: #1

Principal Investigators:
Vitaly A. Zlotnik
University of Nebraska-Lincoln

Sherilyn C. Fritz

James B.Swinehart

David B. Loope

Abstract

The surface morphology of the Sand Hills dune field combined with the west-east regional groundwater flow creates numerous lakes in topographic depressions. In Sheridan and Garden counties, there are approximately 400 lakes with surface areas larger than 4 ha. Concentration of total dissolved solids (TDS ) in lake water ranges from 0.3 g/L to more than 100 g/L and pH ranges from 8.4 to more than 10. Although a significant amount of work has been done on the hydrology and chemistry of several lakes, the lake salinity patterns have not been explained.
Overall goal of this study is to investigate hydrogeological factors that control the salinity of the Sand Hills lakes. Specific objectives of this study are as follows:
- to investigate sources of lake salinity associated with groundwater flow in a 400 sq. km area northwest from the Crescent Lake National Wildlife Refuge (CLNWR) using the latest groundwater sampling methods;
- to compare groundwater and aquifer properties near two typical lakes with contrasting salinity (fresh versus saline) for understanding hydrogeological conditions that lead to salinity differentiation;
- to delineate hydrogeological properties of the surficial eolian aquifer, underlying sediments, and organic materials for developing a large-scale model of lake-aquifer interactions of the area.
We will capitalize on the use of the UNL direct-push equipment (Geoprobe ®). Along three transects in the area, data will be collected in five holes. In each hole, several parameters will be obtained at given depths. In addition to water table depth from the ground surface, we will collect electrical conductivity (EC), groundwater sample, hydraulic conductivity, and a sediment core at depths up to 35 m. EC will guide the high-resolution hydrostratigraphic characterization of the aquifer.
Such methodology will provide data on the aquifer geology and parameters that will help to quantify the lakes-aquifer fluxes determining the magnitude of spatial and temporal variability in lake chemistry.

Progress/Completion Report PDF