TOWARDS QUANTIFICATION OF SALINITY DYNAMICS OF MODERN LAKES IN SEMI-ARID DUNE ENVIRONMENTS: NEBRASKA SAND HILLS

Salinity patterns in shallow lakes are commonly spatially variable in semi-arid dune environments on all continents. Typically, these lakes exist in sparcely-populated regions, and their hydrology is poorly characterized. The influences of evaporation, groundwater, and major mass transport mechanisms (advection, convection, diffusion, dispersion) are commonly understood on a conceptual level. Still, holistic models delineating the salinization pathways and analyses of factors controlling the extent of salinization are in an early stage of development. Without understanding the dynamics of individual lakes in response to climate and three-dimensional salinity variability within an ensemble of lakes, the existing spatial salinity patterns may be not apparent.

The Sand Hills of Nebraska host hundreds of shallow lakes that vary widely in salinity; this is an exemplary area to study this phenomenon. The area near Crescent Lake National Wildlife Refuge, which covers about 400 sq. km, exhibits salinity patterns that have not been explained by existing models. We discuss the available and needed background data necessary to develop a model for the lake-aquifer system. We characterized the surface water chemistry of all lakes in the area. Data for eleven near-lake sites were obtained using direct-push methods of aquifer characterization.

We attempt to formulate major research questions in the analyses of salinity dynamics as follows: How did lakes emerge in dune environments? How do lakes interact with groundwater? What is the relationship between groundwater salinity and lake salinity? Are there tools and data available to simulate all transport mechanisms? Our hydrogeology and geochemistry data will be used for developing conceptual and mathematical models of saline lakes in dune environments.