Simulating impacts of climate and land use change on regional hydrology at fine resolution with the integrated landscape hydrology model (ILHM)

Climate and land use change will alter hydrology and impact water resources globally, but the effects of these changes are experienced locally. In the U.S., most water resource and land use planning takes place at intermediate scales. Unfortunately, existing hydrologic simulation tools are either semi-empirical models well suited for regional- to global-scale modeling, or fully-coupled process-based models useful only for very small watersheds. This mismatch of scale and purpose between predictive modeling and resource management limits our ability to quantify, respond to, and mitigate potential changes. The Integrated Landscape Hydrology Model (ILHM) is a novel water- and energy-balance physics-based model capable of simulating regional scale (>10,000 km^2) hydrology at fine resolution (~100 m). ILHM simulates nearly the entire terrestrial hydrologic cycle using readily available GIS, remote sensing, and gauged inputs. Here we present a series of 120 year simulations of the Muskegon River Watershed in Michigan, U.S.A. that backcast to 1980 and forecast to 2100. We compare the impacts of simulated climate change alone to the combined impacts of simulated climate and land use changes. Under all scenarios, soil moisture, evaporation, transpiration, ground water recharge, and stream flows are significantly altered.