Indirect Techniques for Erosion Protection
are associated with most other indirect protection techniques are eliminated. Also, by
providing a rocky substrate for benthic organisms and cover for fish, and by altering the
velocity distribution across the cross-section and in the vertical, they improve habitat
conditions for some species of aquatic life. Whether detrimental effects would accompany
these beneficial effects in other applications would depend upon the environmental context
of a specific application.
In recent years, bendway weir theory has been applied to small stream applications as
a streambank protection measure (Figure 8.4). The first small stream application was in 1993
on Harland Creek near Tchula Mississippi where fifty-four bendway weirs were constructed
(Derrick, 1997a). Since that time, bendway weirs have been built on numerous small streams
throughout the country. Some of theses projects have used low-cost, hand placed stone weirs,
and weirs constructed of tree trunks and geobags to protect farmland (Derrick, 1997b).
Because this is a recently developed technique, the long term success of these structures as
a bank stabilization scheme is not known. Further research and monitoring of existing
structures is needed to document the long-term performance and to develop more definitive
design criteria.
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