Water Stewardship Information Sources
| Citation | Hogan, DL and Millard, TH. 1998. Gully assessment methods. In: Hogan, D.L., P.J. Tschaplinski, and S. Chatwin (Editors). B.C. Min. For., Res. Br., Victoria, B.C. Land Manage. Handb. No. 41. |
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| Organization | FLNRO |
| URL | https://www.for.gov.bc.ca/hfd/pubs/docs/Lmh/Lmh41.htm |
| Abstract/Description or Keywords | Large woody debris (LWD) is a fundamental structural element in small coastal streams found throughout the Pacific Northwest (see, for example, Keller and Swanson 1979; Marston 1982; Hogan 1987; Robinson and Beschta 1990). The influence of log jams on channel morphology, riparian areas, and fish habitat, both in Carnation Creek and in streams on the Queen Charlotte Islands, is reviewed by Hogan et al. (this volume). In the early phases of channel adjustment following jam formation, fish habitat is degraded as spawning areas (riffles)riffles are buried (upstream of the jam) or eroded (downstream of the jam), rearing pools are infilled, and egg incubation environments are smothered with fine-textured sediments. Over the long term (on the order of half a century), log jams deteriorate and create complex, diverse stream channels and riparian areas that become highly productive fish habitats. Log jams are spatially prevalent in small coastal streams. Considering longitudinal surveys that included almost 44 km of channel in streams throughout the Queen Charlotte Islands, Hogan et al. (in prep.) found the median spacing of log jams to be 2.85 and 2.30 bankfull widths (Wb) in forested and logged streams, respectively. In Carnation Creek, individual log jams determine local channel morphology and control the pattern of channel evolution, both upstream and downstream of a jam (see Figure 5, Hogan et al., this volume). Because of the importance of log jams, it is therefore important that channel assessments in small coastal streams, documenting changes in channel morphology and associated impacts on fish habitat, use a consistent and repeatable classification of log jams and their related morphological features. This paper presents just such a classification, one that is field-based and can be used to assess the spatial and temporal response of a stream channel to disturbance. The objective of the classification is to assess current channel conditions and to consider the probable long-term temporal response of a channel following the development of a log jam. The classification is based on a description of log jams and their individual characteristics, an inventory of relevant field indicators of channel disturbance associated with each jam, and the identification of the stage of channel recovery following jam formation. |
| Information Type | Article |
| Regional Watershed | Coast Region |
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| Comments | |
| Project status | complete |
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