PARENT SESSION
Oral Session # 28: Ecological Modeling II.
Presiding: R Park
Tuesday, August 5. 1:30 PM to 5:00 PM, SITCC Meeting Room 102.
A generic lake model of water balance: Impacts of climate variation and lake type.
Cardille, Jeffrey*,1, Coe, Michael1, Turner, Monica1, Carpenter, Stephen1, Foley, Jonathan1, Vano, Julie1, 1 University of Wisconsin-Madison, Madison, WI, USA
ABSTRACT- Lakes and terrestrial ecosystems interact through flows of water, organic carbon and nutrients, yet understanding these interactions across spatially heterogeneous landscapes is incomplete. We studied hydrologic fluxes in the Northern Highlands Lake District, Wisconsin (USA), a forested land-water mosaic in which 13% of the surface area is covered by lakes. A simple lake model that represents key fluxes and components of the integrated land-lake system was developed to address the following questions: (1) What is the relative effect on water balance of lake type and climate? (2) What lake types are most sensitive to climatic variation (e.g., drier vs. wetter climate), and what lake types are less sensitive? The model simulates hydrologic fluxes for mounded, seepage, and drainage lakes by using simple equations of groundwater and surface flows. The three lake types were parameterized using long-term data for well-studied lakes in the region, and basic water balance results-- modeled volume, stream outflow, groundwater outflow, and flow timing-- were compared to published data. Water balance of real lakes under current conditions was well-represented by this general model and a common set of parameters. Simulation experiments were conducted for each lake type using climate scenarios that included current average climate and the wettest and driest months recorded between 1960 and 1990. Simulation results indicate that lake response to climate variation will differ substantially by lake type. In scenarios of increased or decreased precipitation, lakes can change type as particular inputs and outputs emerge or disappear, and these changes can strongly affect biogeochemical cycles due to alterations of flow paths and residence times. Through exploration of lake responses with this model, we can begin to conceptualize the interactions between terrestrial and aquatic ecosystems in this complex landscape.
Key words: Groundwater, Temperate, Lake, Wisconsin