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Fine-Resolution, Regional-Scale Terrestrial Hydrologic Fluxes Simulated with the Integrated Landscape Hydrology Model (ILHM). David W Hyndman Anthony D Kendall. Unprecedented Changes. Land Use Intensification. Climate Change. Land Use Change. USCB and USDA. IPCC AR4. Pijanowski (Purdue).
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Fine-Resolution, Regional-Scale Terrestrial Hydrologic Fluxes Simulated with the Integrated Landscape Hydrology Model (ILHM) David W Hyndman Anthony D Kendall
Unprecedented Changes Land Use Intensification Climate Change Land Use Change USCB and USDA IPCC AR4 Pijanowski (Purdue)
Integrated Landscape Hydrology Model (ILHM) • Integrates 4 domains of hydrologic modeling • Intended for large-scale, fine-resolution simulations • Modular code, readily expandable • Readily incorporates GIS, remote sensing inputs
Muskegon River Watershed, MI • ~7400 km2 • Climate & ecological gradients • Lake effect precipitation • Deciduous/Mixed transition • Major historical land use change • Forest Agriculture • Agriculture Forest and Urban
Expanded Model Domain • ~19,000 km2 • 100 to 400m grid cells • 28-year simulation • 1980 – 2007 • Hourly timesteps
Select Input Data Types • GIS Inputs • Land use • Soil texture • Subsurface geologic maps • Elevation map • Gage climate data • Precipitation • Solar radiation • Windspeed • Relative humidity • Air/soil temperatures • Distributed remotely sensed inputs • NEXRAD precipitation • Satellite Leaf Area Index (LAI)
Uncalibrated Streamflow Predictions 3711 sq. km • Baseflows well simulated, regardless of scale – some regional bias • Total discharge error less than 6% of annual precipitation 629 sq. km 43 sq. km
ET and Recharge Averages (1980 – 2007) • Highly spatially variable • Soils, land use, climate variability • Recharge strongly sensitive to lake-effect precipitation
Monthly Watershed-Average Fluxes • 2 annual recharge pulses: snowmelt/spring & early fall • ET dominates during the growing season • Storage in snowpack and soil are important to dynamics
Preliminary Climate Change Scenarios • Average of 24 GCM outputs • A1B, A2, & B1 scenarios • Offset observed data using modeled anomalies
Changes to Groundwater Recharge • Average 2090 - 2099 • More frequent snowmelt in all scenarios • Smaller persistent snowpack • Reduced spring recharge • Less fall recharge
Climate Change Implications • Higher spring water tables • More frequent spring floods • More seasonal wetlands • Earlier decline of summer water table • Lower summer baseflows • Longer low-flow period
Summary • Good predictions without site-specific calibration • Variability is the rule: • Groundwater recharge typically treated as a static input in groundwater models • Strong spatial and temporal variability at all scales • Even 425 m resolution here not sufficient to fully describe land use and soils • Gradients in precipitation and temperature well below typical climate model resolutions • Lake effect not well described by climate models