Water Stewardship Information Sources
| ID | 477 |
|---|---|
| Citation | Dobson Engineering Ltd. 2004. Chase Creek Hydrologic Assessment: Impact of Mountain Pine Beetle Infestations on Peak Flows (Including Application of the Ministry of Forests Extension Note 67). Prepared for Riverside Forest Products Ltd and Tolko Industries Ltd. |
| Organization | Riverside Forest Products Ltd |
| URL | http://www.for.gov.bc.ca/hfd/library/FIA/2005/FIA2005MR024-1.pdf |
| Abstract/Description or Keywords | At the Chase Creek Watershed Advisory Committee meeting that was held at the Quaaout Lodge on March 31, 2004, it was noted that the mountain pine beetle was at elevated levels in portions of the watershed and that the initial watershed management plan was no longer applicable. It was recommended that a ﾓrisk analysis/hydrologic impactﾔ of future harvesting be undertaken. The following report was completed by Dobson Engineering Ltd. (Dobson) at the request of Riverside Forest Products Limited (Riverside), Tolko Industries Ltd. (Tolko), and BC Timber Sales (BCTS), to estimate the hydrologic impact of the current mountain pine beetle infestation as well as the potential impact if the beetle was to attack all of the remaining lodgepole pine in the snow sensitive zone in the watershed. As requested, the equivalent clear-cut area (ECA) evaluation utilizes the results of the Ministry of Forests, Forest Sciences Program Extension Note 67 (Schnorbus et. al. 2004) investigating the influence of forest development on the quantity of flows in a snowmelt hydrologic regime. There was considerable discussion at the March 31st meeting regarding the epidemic expansion of the beetle in the watershed. Due to this recent rise in the beetle population in 2003 and the expected expansion in 2004, the management direction provided in the report titled Chase Creek Watershed Management Plan approved in 1999 was no longer achievable. This report summarizes the results of loss of forest cover and peak flow impacts from two unique scenarios. Scenario 1 illustrates the ﾓworst caseﾔ for peak flows should all the susceptible pine succumb to the mountain pine beetle and assumes the loss of all mature lodgepole pine within the snow sensitive zone of the Chase Creek watershed. Scenario 2 illustrates what the expected impact will be as a result of the loss of currently identified infested pine (2003) within the timber harvest landbase portion of the snow sensitive zone. The reader is reminded that this is an assessment of the loss of the mature pine due to insects. The impacts on peak flow have been assessed based on the loss of forest cover and the resulting increase in water yields due to changes in water balance (i.e. increases to snow accumulation and snowmelt). Timber harvesting is not considered in the initial assessments since it is not the cause of the loss of forest cover, it is the beetle. The impacts of proposed salvage harvesting are considered separately since the harvesting is proposed in response to the beetle and is focused on those areas that will have limited impacts on the water resource. Conclusions arrived at within this report are based on modeling which incorporates recently acquired information. The first is the results of snowline research in the Chase Creek watershed that was initiated by Riverside in 1999. As a result of this research a more refined determination of the snowline position was achieved. The snowline delineates the portion of the watershed with a melting snowpack during the peak flow period (addressed in greater detail in section 3.0 - Snow Sensitive Zone Determination). Research conducted each spring since 2001 confirms that the recently revised snow sensitive area is smaller than that originally suggested by the H60 line proposed in the Interior Watershed Assessment Procedure. The second piece of information is the Ministry of Forests Forest Sciences Program Extension Note 67 released in 2004 that summarizes the results of research into the impacts of timber harvesting on peak flows in the Upper Penticton Creek research watersheds. The results of this article suggest that increases to peak flows related to ECA are less than previously suspected for watersheds with similar morphology and geographical setting. watershed assessment, mountain pine beetle, peak flow, flood |
| Information Type | report |
| Regional Watershed | Thompson |
| Sub-watershed if known | Chase Creek |
| Aquifer # | |
| Comments | |
| Project status | complete |
| Contact Name | |
| Contact Email |