Parameterization of Lakes and Wetlands for Energy and Water Balance Studies in the Great Lakes Region

Lakes and wetlands are prevalent around the Great Lakes and play an important role in the regional water and energy cycle. However, simulating their impacts on regional-scale hydrology is still a major challenge and not widely attempted. In the present study, the Variable Infiltration Capacity (VIC) model is applied and evaluated with a physically based lake and wetland algorithm, which can simulate the effect of lakes and wetlands on the grid cell energy and water balance. The VIC model was calibrated at 10 U. S. Geological Survey (USGS) stream gauging stations against daily streamflow records for the period of 1985-95, and successfully evaluated for the period of 1996-2005. Single-grid sensitivity experiments showed that runoff, baseflow, and inundation area were sensitive to the lake model parameters. Simulations were also conducted to analyze the spatial and temporal variability of inundation area for the period of 1985-2005. Results indicated that water and energy fluxes were substantially affected when lakes and wetlands were included in model simulations. Domain-averaged annual mean evapotranspiration (ET) was increased by 5% while annual mean total runoff was decreased by 12% with lakes and wetlands. Latent heat flux increased while sensible heat flux decreased because of the inclusion of lakes and wetlands.