HR: 0800h
AN: H41D-0436    [Abstracts]
TI: Integrating landscape and hydrologic simulation models to assess the influence of fire-suppression on water yield from forested Rocky Mountain watersheds
AU: * Ahl, R S
EM: rob.ahl@umontana.edu
AF: The University of Montana, College of Forestry and Conservation, 32 Campus Drive, Missoula, MT 59812 United States
AU: Woods, S
EM: scott.woods@cfc.umt.edu
AF: The University of Montana, College of Forestry and Conservation, 32 Campus Drive, Missoula, MT 59812 United States
AU: DiLuzio, M
EM: diluzio@brc.tamus.edu
AF: Grassland, Soil & Water Research Laboratory, USDA-ARS , 808 East Blackland Road, Temple, TX 76502 United States
AB: Most of the water supply for semi-arid western North America originates as snow that is deposited and temporarily stored in forested, high elevation watersheds. Snow accumulation in these watersheds varies with climate, elevation, topography and forest vegetation characteristics. Canopy structure is an especially important vegetation characteristic because of its effect on the interception component of the water budget and the wind speed and solar radiation flux at the snow surface. Canopy structure is a function of forest composition, structure and extent, all of which are shaped by disturbance processes such as fire, insect and disease outbreaks, and human-induced changes. Changes in the frequency and magnitude of these disturbance processes such as those that have occurred due to fire suppression lead to changes in forest structure, and this may result in long term reductions in water yield from forested watersheds. We have developed a methodology for linking, spatially explicit, time-series, landcover and hydrologic analysis at the watershed scale, with the goal of quantifying changes in long term water yield due to fire suppression and other management scenarios. Output from the SIMPPLLE (Simulating Patterns and Processes at Landscape Scales) vegetation simulation model is classified and processed to provide input to the SWAT (Soil and Water Assessment Tool) hydrologic model. SIMPPLLE integrates various data sources to simulate vegetation growth and disturbance pathways for forested environments in the Rocky Mountains. We used SIMPPLLE to simulate landcover change 300 years forward from current conditions for 1) fire suppression and 2) natural succession management scenarios. Grid-based maps were produced for each scenario at decadal intervals and used as input for SWAT. SWAT was calibrated using current landcover data and five years of daily streamflow records, and a Nash-Sutcliffe model efficiency of 0.90 was achieved. The calibrated SWAT model was then used to simulate the hydrologic output for each 10 year time step over the 300 year simulation period for both management scenarios. The results indicated significant differences in landcover component composition, configuration, and ultimately water yield when forest fires were suppressed. Although landcover composition remained fairly stable, significant differences in distribution and configuration became evident after only a half-century of active fire suppression. These differences also translated into differences in basin level water yield.
DE: 1803 Anthropogenic effects (4802, 4902)
DE: 1847 Modeling
DE: 1860 Streamflow
DE: 1879 Watershed
SC: Hydrology [H]
MN: Fall Meeting 2005