Project Code: WEYDV-02-042
Program: FRIP
Area:Inventory and Planning
Sponsor:Weyerhaeuser Company Limited
Region:Slave Lake
Project Status:Complete

This project initiated a watershed sensitivity analysis of the lower part of the Marten River Watershed within the Weyerhaeuser Slave Lake Management Area. The specific objectives included preparing a general description of the hydrology of the Marten River and the Slave Lake region, estimating the potential future harvesting impacts on annual water yield and channel flow in the watershed, and preparing in-house and public presentations to explain/describe the hydrologic impacts of land use in the Marten River watershed. Three harvesting scenarios were simulated in the WRENSS analysis (Water Resources Evaluation of Non-point Silvicultural Sources). The purpose of the FVS-WRENSS post-processor is to predict water yield changes caused by silvicultural actions or stand disturbance. A RHESSys analysis was also performed to evaluate the hydrologic impacts of a first pass cutting that was planned. The results indicated that increased annual flows would be below the 15% criterion set out by AEP, most likely ranging from 3-10%. Large increases in peak flows may occur in years of high annual precipitation, as well as during high volume and long duration rainstorms. Peaks following logging could increase by 34% above unharvested conditions in wet years. Increases following extensive forest cover removal that exceeds 50% or more of the watershed (like in a wildfire) could increase peak flows by 45-218%. The final report was prepared by Watertight Solutions Ltd. in January 1999, entitled “Watershed Analysis of Marten Creek, Located near Slave Lake Alberta”.