Impacts of Land Cover and Land-use Change on the Water and Energy Cycle of the Great Lakes Region

The rate of land use change in recent centuries is much faster than that in the past. Much of the pre-settlement forestation in the Great Lakes region has been harvested and converted to agricultural land uses or early successional forests. This has resulted in large-scale water and energy cycles changes in the region. It is therefore important to understand the impacts of historical land cover and land-use change, to put ongoing modifications into the proper context. The focus of this study is to explore how land-use changes from pre-settlement to modern vegetation in three Great Lakes states: Minnesota, Wisconsin, and Michigan; have affected the hydrologic cycle in the region. The Variable Infiltration Capacity (VIC) model is used to study water and energy fluxes at 1/8 degree resolution in the Great Lakes region. Land Data Assimilation System (LDAS) meteorological and soil data as well as pre-settlement and modern vegetation data resulted from the USGS Land Use History of North American (LUHNA) were used as model input. The model simulated water and energy fluxes under pre-settlement and modern vegetation conditions using 50 years of meteorological forcings. Results were compared between the simulations to assess the impacts of land-use change on water and energy fluxes. Simulations indicate that deforestation has played a large role in changing the hydrologic response of the basin to cold season processes (snow and soil frost) as well as in the year round storage of soil moisture and generation of runoff. This large-scale hydrology study will provide the basis for further research on climate change, frozen soil and cold season processes over the entire Great Lakes region.