[Coastal Watershed Assessment Procedure Guidebook Table of Contents]
The CWAP procedure
The multi-agency round table
The first step of the procedure requires that a round table meeting be organized, attended by the Ministry of Forests district planner, the timber officer or district geoscientist, and the regional hydrologist; and representatives of BC Environment; Department of Fisheries and Oceans (if anadromous fisheries are involved); Ministry of Health (if necessary for a community watershed); and timber, water, and range licensees.
At the first meeting, the watershed management issues of concern should be discussed and clearly defined (such as why this particular watershed assessment is required). Other issues that should be resolved at this meeting include:
- the location of the point(s) of interest
- the sub-basins that have particular concerns
- the sub-basins that might need individual analysis
- responsibility for doing and paying for the analysis
- terms of reference for the round table process, including the decision-making process.
The WAP applies to that portion of the watershed above the point of interest (POI). The POI in a community watershed is usually the lowest water intake in that watershed (see Appendix 2). In a fish-bearing stream it is usually the entire reach that contains fish. Once the POI is determined, the watershed above that point is divided into smaller watersheds (sub-basins) according to the guidelines provided in Appendix 2.
The process of having the round table at the outset, identifying all the watershed concerns and defining the sub-drainages of interest, is critical to the success of the entire assessment procedure. Although Appendix 2 provides a suggested method for dividing the watershed into sub-basins and determining the POI, these are only guidelines. The round table can override these guidelines at any time to make them more applicable to specific circumstances.
The watershed should be coded according to its gazetteered name and its unique numeric identifier, using the British Columbia hierarchical watershed coding system.
Level 1 analysis
Level 1 of CWAP involves the collection and collation of data that describe the basic geophysical characteristics of the watershed and the extent and location of harvesting activities in the watershed. Most of the information required can be obtained from a variety of maps—information on topography, soils, bedrock geology and logging history. Level 1 also requires that landslides be counted from the most recent aerial photographs (or from a helicopter survey). Except for the latter requirements, all of the information can be extracted from a geographic information system (GIS).
In the analysis, perform the following tasks:
- make 16 types of measurements on maps and aerial photos
- generate 15 key indicators using the above measurements
- calculate hazard indices for peak flow, surface erosion, riparian buffers, landslide, and headwaters, using the 15 key indicators (see below).
The sections on “The level 1 analysis procedure” and “Interpretations and recommendations” describe the above process in detail and include forms for recording results.
The 15 impact indicators
- Peak flow index (based on elevation-weighted equivalent clearcut area determination)
- Road density (used for assessing peak flow changes)
- Road density (used for assessing surface erosion)
- Density of roads on erodible soils
- Density of roads less than 100 m from a stream
- Density of stream crossings
- Portion of stream logged
- Portion of fish stream logged
- Portion of mainstem logged
- Density of landslides in the watershed
- Number of large landslides hitting the mainstem stream
- Density of roads on potentially unstable terrain
- Percentage of logged, potentially unstable terrain
- Density of streams logged on slopes >60%
- Density of stream crossings on slopes >60%
Level 2 and 3 analyses
Depending on the results of the level 1 analysis, more detailed analyses (levels 2 or 3) may be required in high hazard watersheds or sub-basins. A level 2 analysis is an overview stream channel assessment performed by an individual with some basic experience in hydrology and/or geomorphology (see the section, “Level 2 watershed assessment,” as well as the Channel Assessment Procedure Guidebook). A level 3 analysis is a very detailed analysis, involving mostly field work. It must be performed by a watershed specialist.
Developing watershed constraints for the forest development plan
The information and interpretations provided by the assessment will be used to identify in which sub-basins certain activities are constrained over the next 5 to 10 years. From this, planning constraints will be developed and applied to the forest development plan.
Examples of the type of recommendations that might be developed are:
- restrictions on clearcut harvesting in a particular sub-basin or watershed for a 5-year period
- restrictions on high elevation logging for a 10-year period
- restrictions on further road development in unstable areas
- requirements for a road deactivation plan to be instituted before any further road development in a particular sub-basin.
It is rare that all resource activity would be restricted everywhere in the watershed, but it is possible that in extremely sensitive, extremely damaged watersheds such restrictions would apply until restoration had occurred.
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