title: Uncertainty assessments and hydrological implications of climate change in two adjacent agricultural catchments of a rapidly urbanizing watershed.
abstract: Lake Simcoe is the most important inland lake in Southern Ontario. The watershed is predominantly agricultural and under increasing pressure from urbanization, leading to changing runoff patterns in rivers draining to the lake. Uncertainties in rainfall-runoff modeling in tributary catchments of the Lake Simcoe Watershed (LSW) can be an order of magnitude larger than pristine watersheds, hampering water quality predictions and export calculations. Here we conduct a robust assessment to constrain the uncertainty in hydrological simulations and projections in the LSW using two representative adjacent agricultural catchments. Downscaled CGCM 3 projections using A1B and A2 emission scenarios projected increases of 4°C in air temperature and a 26% longer growing season. The fraction of precipitation falling as snow will decrease. Spring runoff is an important event in LSW but individual HBV best calibrated parameter sets under-predicted peak flows by up to 32%. Using an ensemble of behavioral parameter sets achieved credible representations of present day hydrology and constrained uncertainties in future projections. Parameter uncertainty analysis showed that the catchments differ in terms of their snow accumulation/melt and groundwater dynamics. Human activities exacerbate the differences in hydrological response. Model parameterization in one catchment could not generate credible hydrological simulations in the other. We cautioned against extrapolating results from monitored to ungauged catchments in managed watersheds like the LSW.
authors.affiliation: Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, ON K9J 7B8, Canada; Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden. Electronic address: oni.stephen@slu.se.
authors.forename: S K
authors.initials: SK
authors.lastname: Oni
authors.affiliation: Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden; Environmental and Resource Studies, Trent University, 1600 West Bank Drive, Peterborough, ON K9J 7B8, Canada.
authors.forename: M N
authors.initials: MN
authors.lastname: Futter
authors.affiliation: Faculty of Environmental Studies, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada.
authors.forename: L A
authors.initials: LA
authors.lastname: Molot
authors.affiliation: Environmental and Resource Studies, Trent University, 1600 West Bank Drive, Peterborough, ON K9J 7B8, Canada.
authors.forename: P J
authors.initials: PJ
authors.lastname: Dillon
authors.affiliation: Environmental and Resource Studies, Trent University, 1600 West Bank Drive, Peterborough, ON K9J 7B8, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Crossman
mesh_terms: D000383:Agriculture / Q000706:statistics & numerical data*; D057231:Climate Change; D062070:Hydrology; D060106:Lakes; D015233:Models, Statistical; D009864:Ontario; D045483:Rivers; D012621:Seasons; D035501:Uncertainty; D014507:Urbanization / Q000639:trends*; D014872:Water Movements; D014881:Water Supply / Q000706:statistics & numerical data*
keywords: Climate change; Hydrological change; Lake Simcoe; Phenology; Statistical downscaling; Uncertainty analysis