Fine-Resolution, Regional-Scale Terrestrial Hydrologic Fluxes

Simulated with the Integrated Landscape Hydrology Model

(ILHM)

David W Hyndman

Anthony D Kendall

Unprecedented Changes

Pijanowski (Purdue)

Land Use Change

IPCC AR4

Climate Change Land Use Intensification

USCB and USDA

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

– Baseflows well simulated, regardless of scale – some regional bias– Total discharge error less than 6% of annual precipitation

43 sq. km

629 sq. km

3711 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