Impacts of Climate Variation and Catchment Area on Water Balance and Lake Hydrologic Type in Groundwater-Dominated Systems: A Generic Lake Model

Abstract

Lakes are a major geologic feature in humid regions, and multiple lake hydrologic types exist with varying physical and chemical characteristics, connections among lakes, and relationships to the landscape. The authors developed a model of water fluxes through major components of groundwater-dominated lake catchments in a region containing thousands of lakes, the Northern Highland Lake District (NHLD) of northern Wisconsin and the Upper Peninsula of Michigan. The model was calibrated with data from widely differing lakes using the same set of simple equations to represent the hydrologic type, water residence time, and amount and timing of stream and groundwater flows of representative lakes in today's climate. The authors investigated the sensitivity of the water balance of a set of three connected representative lakes and their catchments to systematic increases and decreases in the precipitation regime, and contrasted results using lake-specific morphometry to those for a lake having size and shape parameters typical of the region. Results indicate that a common set of equations can successfully represent major water balance characteristics of the three basic lake hydrologic types (hydraulically mounded, groundwater flowthrough, and drainage) in the NHLD. Sensitivity of modeled lakes varied by lake type, with drainage lakes more strongly buffered against substantial hydrologic changes in extreme climate scenarios. Catchment-scale water budgets differed substantially among lakes of different types, yet can be understood along a continuum of relative catchment size. These results suggest that a simple model of lake and catchment water balance can be extended to entire lake districts, where the detailed morphometry of most lakes is not well known.