Water Resources Research Act Program

Details for Project ID 2004NE78B

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

Institute: Nebraska
Year Established: 2004 Start Date: 2004-03-01 End Date: 2006-02-28
Total Federal Funds: $19,975 Total Non-Federal Funds: $45,389

Principal Investigators: Vitaly Zlotnik, Sherilyn Fritz, David Loope, James Swinehart

Project Summary: 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.