Simulating the impacts of future land use and climate changes on surface water quality in the Des Plaines River watershed, Chicago Metropolitan Statistical Area, Illinois.

Modeling the effects of past and current land use composition and climatic patterns on surface water quality provides valuable information for environmental and land planning. This study predicts the future impacts of urban land use and climate changes on surface water quality within Des Plaines River watershed, Illinois, between 2010 and 2030. Land Change Modeler (LCM) was used to characterize three future land use/planning scenarios. Each scenario encourages low density residential growth, normal urban growth, and commercial growth, respectively. Future climate patterns examined include the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenario (SRES) B1 and A1B groups. The Soil and Water Assessment Tool (SWAT) was employed to estimate total suspended solids and phosphorus concentration generated at a 10 year interval. The predicted results indicate that for a large portion of the watershed, the concentration of total suspended solids (TSS) would be higher under B1 and A1B climate scenarios during late winter and early spring compared to the same period in 2010; while the summer period largely demonstrates a reverse trend. Model results further suggest that by 2020, phosphorus concentration would be higher during the summer under B1 climate scenario compared to 2010, and is expected to wane by 2030. The projected phosphorus concentrations during the late winter and early spring periods vary across climate and land use scenarios. The analysis also denotes that middle and high density residential development can reduce excess TSS concentration, while the establishment of dense commercial and industrial development might help ameliorate high phosphorus levels. The combined land use and climate change analysis revealed land use development schemes that can be adopted to mitigate potential future water quality impairment. This research provides important insights into possible adverse consequences on surface water quality and resources under certain climate change and land use scenarios.