The Influence of Lakes and Wetlands Parameterization on Regional Water and Energy Fluxes

Abstract

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, we apply and evaluate the functioning of the Variable Infiltration Capacity (VIC) model 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 ten USGS stream gauging stations for the period of 1985-1995 and successfully evaluated for the period of 1996-2005 with respect to monthly streamflow. The model also reproduced daily streamflow reasonably well at the selected gauge stations. 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 significantly affected when lakes and wetlands were included in model simulations. Domain averaged annual mean evapotranspiration (ET) was increased by 9% while annual mean total runoff was decreased by 17% with lakes and wetlands. Net radiation and latent heat flux were increased by 6% and 8%, respectively, due to the simulation of lakes and wetlands.