Force gage measurements to characterize bed mobility in two restored reaches of the lower Merced River, California
Dates
Publication Date
2019-10-25
Time Period
2016
Citation
Legleiter, C.J., and Harrison, L.R., 2019, Field measurements for characterizing salmon spawning habitat in two restored reaches of the lower Merced River, California: U.S. Geological Survey data release, https://doi.org/10.5066/P99CWIDL.
Summary
Force gage measurements were used to parameterize a force balance model for the initiation of sediment motion and thus characterize bed mobility for two reaches of the lower Merced River in California's Central Valley. These data were acquired to support research intended to evaluate the extent to which large-scale restoration projects provided improved salmon spawning habitat. A related goal of this study was to improve our understanding of the geomorphic factors influencing spawning site selection by salmon. The force gage measurements were made at the Merced River Ranch and Robinson Reach field sites and involved using a spring-resisting force gage to push a given submerged particle in a bed-parallel downstream orientation and recording [...]
Summary
Force gage measurements were used to parameterize a force balance model for the initiation of sediment motion and thus characterize bed mobility for two reaches of the lower Merced River in California's Central Valley. These data were acquired to support research intended to evaluate the extent to which large-scale restoration projects provided improved salmon spawning habitat. A related goal of this study was to improve our understanding of the geomorphic factors influencing spawning site selection by salmon. The force gage measurements were made at the Merced River Ranch and Robinson Reach field sites and involved using a spring-resisting force gage to push a given submerged particle in a bed-parallel downstream orientation and recording the minimum force necessary to initiate sediment motion, following the methods of Johnston et al. [1998]. For each particle, we also recorded the grain size class of the largest retaining sieve (22, 32, 45, 64, 90 or 128 mm), the length of the a, b and c axes of the sediment grain, the axial orientation, and the particle's weight. These values were used to parametrize the force balance model of Wiberg and Smith [1987]. The data required to parameterize this model include the sediment particle diameter, D (m), the cross-sectional area of the grain perpendicular to the flow, AX (m2), the grain volume, V (m3), the grain height above the bed, z (m), the friction angle, phi (degrees), and the ratio of the lift force, FL, to the drag force, FD. The values of each of these parameters are tablulated in a file included in this data release. We calculated the squared function for the logarithmic vertical velocity profile using the height above the bed (z) and roughness length, z0 = D50/30. Values of z0 were 0.00173 and 0.00183 m for the MRR and RR, based on D50 values obtained from local pebble counts conducted in the pool-riffle transition where force gage measurements were obtained in each reach.
Click on title to download individual files attached to this item.
ForceGageMetadata.xml “Metadata” Original FGDC Metadata
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14.05 KB
application/fgdc+xml
Merced_forceGage.csv “Force gage data”
40.6 KB
text/csv
Related External Resources
Type: Related Primary Publication
Harrison, L. R., Bray, E., Overstreet, B., Legleiter, C., Brown, R. A., Merz, J. E., et al. ( 2019). Physical controls on salmon redd site selection in restored reaches of a regulated, gravel‐bed river. Water Resources Research, 55, 8942– 8966. https://doi.org/10.1029/2018WR024428
For questions concerning this data set, please contact:
Dr. Carl J. Legleiter - cjl@usgs.gov, 303-271-3651
Geomorphology and Sediment Transport Laboratory
United States Geological Survey
4620 Technology Drive, Suite #400
Golden, CO 80403
Purpose
Force gage measurements were used to parameterize a force balance model for the initiation of sediment motion and thus characterize bed mobility for two reaches of the lower Merced River in California's Central Valley. These data were acquired to support research intended to evaluate the extent to which large-scale restoration projects provided improved salmon spawning habitat. A related goal of this study was to improve our understanding of the geomorphic factors influencing spawning site selection by salmon.
Rights
Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
