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A GIS/simulation framework for assessing change in water yield over large spatial scales
Dale D Huff1, William W Hargrove, Robin Graham
1Environmental Sciences and Computational Physics and Engineering Divisions, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6038, USA.
Environmental Management
|January 30, 2002
Summary
Vegetation thinning in California
Area of Science:
- Forestry and Hydrology
- Environmental Science
Background:
- Recent legislation mandates vegetation management in California's Central Sierra hydrologic region.
- This initiative includes assessing potential changes in water yield.
Purpose of the Study:
- To develop a combined geographic information system (GIS) and simulation framework.
- To examine the impact of proposed forest thinning on water yield.
Main Methods:
- Generated simulation model inputs based on existing vegetation density and proposed thinning rules.
- Utilized a GIS framework to analyze changes at a 1-km2 map cell level.
- Aggregated results for watershed units using area-weighted averaging for wet, dry, and average precipitation years.
Main Results:
- Simulated changes in water yield were less than 0.5% of expected annual runoff in watersheds where snow is significant.
- These minor changes are likely undetectable using conventional stream flow analysis.
Conclusions:
- Water yield increases may not be sufficient to justify forest thinning activities or offset their costs.
- The study highlights the limited impact of proposed thinning on regional water resources.