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Figure 1: Map of the reach.
Card Picnic Area Logan River
Date of observations: February 7th, 2025
The following observations and data were gathered near the Card Picnic Area up logan canyon. The yellow polygon shows the extent of the reach were data was collected.
Field Map and Cross Section
Figure 2: Field map of the reach.
Figure 3: Hand drawn cross section
Very rough field map of the reach sampled. The south side of the river near the eddy is confined by a steep limestone cliff while the north side is unconfined and shows signs of previous flooding.Â
Rough cross section of the sample reach. We choose a location upriver of the eddy due to depth and ease of wading.
Estimated Discharge
To calculate the discharge of the stream we measured the length width and depth of the stream using a tape measure as well as velocity using an orange peel. Our cross section was 42 ft wide. Depth was measured at 9 points across the channel with an average depth of 14.14 in and a maximum depth of 27 in. We found that the rough cross-sectional area was 61.53 ft^2. To measure velocity we walked 25 ft upstream and placed an orange peel in the thalweg. The orange peel took 17.9 s to travel 25 feet giving us a surface velocity of 1.39 ft/s. To calculate discharge we used the equation Q=V*A, our estimated discharge was 88.53 ft^3. The USGS stream gauge for the Logan River above First Dam shows that the flow for the same date and time was 120 ft^3 however our differences could be due to sampling area or the stream gauge being further downstream.
Figure 4a: Example of convergent flow. Blue arrows are flow direction.
Figure 5a: Example of divergent flow. Blue arrows are flow direction.
Figure 6a: Example of uniform flow. Blue arrows are flow direction.
Figure 4b: Surface flow type for figure 4a. Blue arrows are flow direction.
Figure 5b: Surface flow type for figure 5a. Blue arrows are flow direction.
figure 6b: Surface flow type for figure 6a. Blue arrows are flow direction.
Figure 6: Shows Flow Separation, Flow Seam, Reattachment Zone, and Shear Zone Type. Blue arrows are flow direction.
Hydraulic Jump
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