Integrated, Regional-Scale Hydrologic Modeling of Inland Lakes

Inland lakes constitute an important global freshwater resource and are often defining features of local and regional landscapes. While coupled surface water (SW) and groundwater (GW) models are increasingly available, there is a clear need for spatially explicit yet computationally parsimonious modeling frameworks to explore the impacts of climate, land use, and other drivers on lake hydrologic and biogeochemical processes. To address this need, we developed a new method to simulate daily water budgets for many individual lakes at large spatial scales. By integrating SW, GW, and lake water budget models in a simple manner, we created a modeling framework capable of simulating the historical and future hydrologic dynamics of lakes with varying hydrologic characteristics. By extension, the model output enables ecological modeling in response to hydrologic drivers. As a case study, we applied the model to a large, lake-rich region in northern Wisconsin and Michigan, simulating daily water budgets for nearly 4,000 lakes over a 36-year period. Despite minimal calibration efforts, our simulated results compared reasonably well with observations and more sophisticated modeling approaches. Our integrated modeling requires very limited information, can be run on readily available computer resources, such as a desktop PC, and can be applied at regional, continental, or global scales, where necessary model setup and forcing data are available.