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Contextual Analysis
The Upper East Fork of the South Fork Trask in Context:
an Outline December 1, 2006
A landscape contextual assessment of the upper East Fork of the South Trask (EFSF) will provide background information on the physical, biological, and land use/disturbance characteristics of the watershed. This assessment provides context for understanding how various biophysical processes influence the aquatic environment and will allow us to predict the effect of management actions. Essentially this report will catalogue what information is available on the Upper EFSF Trask River.
Oregon Historical Society Photograph (CN 002633) of a fish collecting cage and rack across the Trask River in Tillamook County (1914).
Tom Lisle suggested that a key goal of conducting a landscape contextual assessment would be to roughly predict the relative strength of changes caused by treatments and their links to downstream effects with ongoing changes and trajectories from past events. The assessment could also be used to guide the measurement design and techniques.
I. Upper EFSF Trask Watershed location within the North Coast of Oregon and specifically Tillamook Bay.
This section will provide general information (e.g., geology/geomorphology, vegetation, etc.) of the regional environment.
II. EFSF Trask Study area physical factors: upslope
- Bedrock and surficial geology Geomorphology (use LiDAR to help map terrains)
- Sediment sources and delivery processes from both background and human caused (could have human caused in later section).
- Soils
- Climate (include storm/drought history)
III. Fluvial context
- Hydrologic history of Trask and nearby streams (mainly peak flows;
- Stream network (ODF fish streams, compare to LiDAR)
- Channel morphology. Most basic product: stream gradient and confinement map- potentially available from
- Channel capability to transport sediment (some index of stream power to understand what streams can move what sizes of sediment)
- Other water quality parameters: sources of water quality information in or near the watershed.
- Some DEQ ambient monitoring (mainly downstream)
- Temperature data within (Trask sites from summer 2006, RipStream and other sources;)
IV. Human use context (vegetation patterns: background, fire and harvest)
- Vegetation type and extent. Fire history: re-construct fire history of watershed including timing and extent of salvage logging. Look for pre-burn aerial photos.
- Document any pre-burn harvest/road building activity
- Post-burn replanting and stand development)
- Road network development (historic and recent)Recent (i.e., post-burn) harvest, set prep, and re-planting
- Recent thinning, type (mainly cable to roadways) and extent
- Other forest related projects: "stump drop", LWD placement (Trask, Pothole)
- Recreational activities and management (i.e., road blockages to control entry)
- Stand type
V. Biological context
- Fish distribution, fish sampling to date. Historic fish information.
- Locations of invertebrate sampling
- Beaver Trapping Records
VI. Other studies in or near the EFSF Trask pertinent to this project
- Tillamook Estuaries Partnership (TEP): they are currently working on a project to: "Characterize ambient water quality and physical habitat with a focus on sediment impairment in the Tillamook Bay Watershed, including the Trask River Watershed. Excessive instream fine sediments have been identified as a potential concern by TEP, but until now there has not been a sufficiently rigorous and practical way to evaluate impairment on a large scale."
VII. Synthesis of contextual analysis
- How the pieces fit together to influence form and process throughout the basin including the small watersheds
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Background