Changes in floodflow characteristics of a rectified channel caused by vegetation, Jackson, Mississippi
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Abstract
Extreme changes in velocity, stage, and Manning's roughness coefficient, n, were observed during the first year after canalization of Hanging Moss Creek at Jackson, Miss. Additional changes were observed during the following 8 years. The channel, constructed during the summer of 1963, had a 50-foot-wide bottom, 2:1 side slopes, and 12-foot depth. In March 1964, average velocities of 7.8 feet per second were measured at a 5 1/2-foot depth in the clean channel and Manning's n was computed to be 0.022. In October 1964 the average velocity was
3.2 fps at a 5 1/2-foot depth and Manning's n was 0.045. The channel was then lined with fairly thick vegetation consisting of small willows,
weeds, and grass. In October 1970 (summer foliage existing) the average velocity was 2.0 fps at a 5 1/2-foot depth and Manning's n was 0.07. Willow trees, 8 to 10 feet high, then lined the channel. In March 1971 (barren foliage), Manning's n was 0.05. In March 1972 (barren foliage), Manning's n was increased to 0.07. These observations indicate that the commonly used values of Manning's n for channel rectification (0.02-0.03) are low and that the carrying capacity of earthen channels may be reduced 50 percent as a result of only 1 year's growth of vegetation and 70 percent as a result of 8 year's growth. The carrying capacity during summer foliage is approximately two-thirds the carrying capacity during barren winter foliage.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Changes in floodflow characteristics of a rectified channel caused by vegetation, Jackson, Mississippi |
| Series title | Journal of Research of the U.S. Geological Survey |
| Volume | 1 |
| Issue | 5 |
| Year Published | 1973 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston, VA |
| Description | 5 p. |
| First page | 621 |
| Last page | 625 |
| Country | United States of America |
| State | Mississippi |
| City | Jackson |
| Other Geospatial | Hanging Moss Creek |
| Online Only (Y/N) | N |
| Additional Online Files (Y/N) | N |
| Google Analytic Metrics | Metrics page |