2019-10-28-minutes-public-works-study-session

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nhc 3 REACH CHARACTER Field Observations The reach of the NF Teanaway, between the proposed realigned lick Creek confluence and the existing confluence (Figure 2), is dominated by a cobble -boulder bed material (Photo 1 through Photo 3) with local areas of scour to bedrock (Photo 2 and Photo 3), as well as transient deposits of pebble ravel and gravel (Photo 4). It has a plane -bed, long proflle morphology with areas of localized scour around large wood (Photo 5), bedrock exposure (Photo 2), and anabranch channel confluences. The river has an Irregular to meandering planform with localized flow splits around nobble bars and a few stable islands. Single -thread segments range in width from about 60 to 100 feet, with a typical width of about 85 feet. Some areas split around bars and are substantially wider (120 to 150 feet), bringing the average channel width to 90 feet. A random -walk Wolman (1954) pebble count (Figure 3) was collected from the head of a large island bar, approximately 375 feet upstream of the proposed Lick Creek confluence location (Figure 2 and Photo 1). This bar head corresponds to the first riffle crest upstream of the proposed confluence. The bar is somewhat bimodal, with small cobble to gravel deposited over a distinctly larger cobble armor layer. It is similar to typical bed conditions observed through the reach, but there is variability around this typical material (Photo 2 through Photo 4). Areas of substantially larger substrate (large cobble to small boulder) are locally present In the thalweg. Several patches of highly mobile pebble -gravel to medium gravel were also observed, but these have little overall Influence on the bed morphology and are interpreted to be transient deposits that were deposited during the falling limbs of the most recent flood(s). Potential impact of Lick Creek relocation on the NF Teanaway River Morphodynamics