Environmental Engineering Reference
In-Depth Information
Top of
streambank
Top of
streambank
Top of
streambank
Top of
streambank
Flow
Flow
Wing
deflector
Wing
deflector
Wing
deflector
Wing
deflector
Scour
pool
Scour
pool
Footer
stones
Footer
stones
Single wing deflector
Double wing deflector
Bottom of bank
Linear deflector
Flow
Top of
bank
Top of
streambank
Cutoff
sills
(Optional)
Lateral or
point bar
Cutoff
sills
Deposition
area
20-30
Flow
Rock vane
Scour
Flow
Lateral or
point bar
Deposition
area
Narrowed
base flow
channel
20-30
Deposition
area
J-rock vane
Scour
Top of bank
Toe of bank
Rock vane and J-rock vane
Linear deflector
Cutoff sill
FIGURE 8.19 Delector types. (From Stormwater Manager's Resource Center, Stream restoration: Flow
delection/concentration practices. Available at: http://www.stormwatercenter.net/.)
Wing Delectors (single): A single wing delector is a triangular structure that extends out
from the streambank into the stream, with the widest portion along the bank and the point
extending into the channel. The purpose of a single wing delector is to change or (delect)
the direction of the streamlow either to narrow and deepen the base low channel or to cre-
ate sinuosity in the channel. When used to narrow and deepen the base low channel, the
single wing delector can also promote the formation of overhead cover (undercut banks)
on the opposite bank.
Wing Delectors (double): Double wing delectors are installed on each bank of a river to
locally reduce the width of the channel, constricting the low of water, creating scour, and
deepening the base low channel. Double wing delectors also create an area of increased
velocity between them, enhancing rifle habitats between and just upstream of the structure.
Rock and J-Rock Vanes: Vanes are linear structures that extend out from the streambank
into the stream channel in an upstream direction and mimic the effect of a tree partially
falling into a stream. Vanes reduce erosion along the streambank, and the “hook” in the
J-hook vane produces a longer, wider, and deeper pool than that created by vane-only
structures.
Cutoff Sills: Cutoff sills are low rock sills, which are frequently used in conjunction with
linear delectors, extending from the streambank into the stream channel at an angle of
20°-30° from the bank in an upstream direction. Cutoff sills promote deposition and bar
formation along the edge of a channel in order to narrow and better deine the base low
channel.
Linear Delector: A linear delector consists of a line of boulders placed within the stream
channel rather than along the bank, to narrow, deepen, and better deine the base low
channel. The top of the delector is generally below the bank-full elevation.
Additional information on delectors and guidance on their design are given by Rosgen (2001),
Heaton et al. (2002), Shields (1983), Shields et al. (1995), and Biron et al. (2004).
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