cut bank:
The concave wall of a meandering stream.
cutoff:
(a) A direct channel, either natural or artificial, connecting two
points on a stream, thereby shortening the original length of
the channel and increasing its slope; (b) A natural or artificial
channel which develops across the neck of a meander loop
(neck cutoff) or across a point bar (chute cutoff).
cutoff wall:
A wall, usually of sheet piling or concrete, that extends down to
scour-resistant material or below the expected scour depth.
daily discharge:
Discharge averaged over one day (24 hours).
debris:
Floating or submerged material, such as logs, vegetation, or
trash, transported by a stream.
degradation (bed):
A general and progressive (long-term) lowering of the channel
bed due to erosion, over a relatively long channel length.
depth of scour:
The vertical distance a streambed is lowered by scour below a
reference elevation.
design flow (design flood):
The discharge that is selected as the basis for the design or
evaluation of a hydraulic structure.
dike:
An impermeable linear structure for the control or containment
of overbank flow. A dike-trending parallel with a streambank
differs from a levee in that it extends for a much shorter
distance along the bank, and it may be surrounded by water
during floods.
dike (groin, spur, jetty):
A structure extending from a bank into a channel that is
designed to: (a) reduce the stream velocity as the current
passes through the dike, thus encouraging sediment
deposition along the bank (permeable dike); or (b) deflect
erosive current away from the streambank (impermeable dike).
discharge:
Volume of water passing through a channel during a given
time.
dominant discharge:
(a) The discharge of water which is of sufficient magnitude and
frequency to have a dominating effect in determining the
characteristics and size of the stream course, channel, and
bed; (b) That discharge which determines the principal
dimensions and characteristics of a natural channel. The
dominant formative discharge depends on the maximum and
mean discharge, duration of flow, and flood frequency. For
hydraulic geometry relationships, it is taken to be the bankfull
discharge which has a return period of approximately 1.5 years
in many natural channels.
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