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Man-induced gradient adjustment of the South Fork Forked Deer River, west Tennessee

Environmental Geology and Water Sciences

By:
,
DOI: 10.1007/BF02449942

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Abstract

Channel modifications from 1968 to 1969 on the South Fork Forked Deer River in western Tennessee have caused upstream degradation, downstream aggradation, and bank failures along the altered channels, adjacent reaches, and tributaries. The result of these adjustments is a general decrease in gradient as the channel attempts to absorb the imposed increase in energy conditions created by channelization. Headward degradation at a rate of approximately 2.57 km/yr on the South Fork Forked Deer River caused from 1.52 m to about 3.14 m of incision over a 13.5 km reach from 1969 to 1981. As a consequence of substantially increased sediment supply, approximately 2.13 m of aggradation was induced downstream of this reach during the same period. This accumulation represents a 60% recovery of bed level at the downstream site since the completion of channel work in 1969. Gradient adjustment with time is described by exponential decay functions. The length of time required for adjustment to some new quasi-equilibrium condition is computed by these decay functions and is about 20 years from the completion of channel work. Adjusted slopes are less than predisturbed values, probably because straightened channels dissipate less energy by friction, allowing more energy for sediment transport. An equivalent sediment load, therefore, can be transported at a considerably gentler slope. The predisturbed slope exceeds the adjusted slope by an order of magnitude on the downstream reach of the South Fork Forked Deer River. ?? 1987 Springer-Verlag New York Inc.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Man-induced gradient adjustment of the South Fork Forked Deer River, west Tennessee
Series title:
Environmental Geology and Water Sciences
DOI:
10.1007/BF02449942
Volume
9
Issue:
2
Year Published:
1987
Language:
English
Publisher location:
Springer-Verlag
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Environmental Geology and Water Sciences
First page:
109
Last page:
118
Number of Pages:
10