Project Code:	WEYDV-02-094
Program:	FRIP
Sponsor:	Weyerhaeuser
Region:	Slave Lake- Willow River watershed
Project Status:	Completed

WEYDV-02-094

Object & Deliverables

The objective of the project was to assess the effects of forest harvesting on water yield and regimen in the Willow River Watershed. This watershed is located 62 km north of Slave Lake, Alberta. Assessment was done using two hydrologic models, WRENSS and RHESSys. Both hydrologic models tested the effects of a no-harvest and harvest scenario. Forest harvesting, which started in the earlier 1960’s is the primary land use in the watershed. Existing and proposed harvesting for up to 2010 will affect 10.2% of the watershed. The Willow River was divided into 10 sub-basins. Simulations were run for the whole watershed and selected sub-basins. Harvesting among the sub-basins ranged from 0-18%. WRENSS was run for 150 years from the start of harvesting and RHESSsy simulations were run for 50-60 years form the start of harvesting. Both models showed that increased water yields and increased peak flows will ocur following forest harvesting in the Willow River and its tributaries. Increases in simulated water yield and peak flows were small and should fall within the boundaries of normal variability. The WRENSS simulations showed maximum annual increase in water yield of 2.3%. Simulations for sub-basins showed increases of 1-5% in annual water yield. Increases in peak flows among the sub-basins were small and varied from 0.1% to 2.1% Peak flow increases for the Willow River varied from .1% to 1.6%. Hydrologic recovery varied from 11 years to 48 years depending on the harvest intensity.

Final Report

The final report was submitted by Watertight Solutions Ltd. in December of 2001, entitled, “Hydrologic Effects of Forest Harvesting in the Willow River Watershed”.