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Natural Stream Channel Design
 he
use of natural channel design is based on fluvial geomorphology
which is the study of how streams form and affect landforms.
These designs use a smaller primary channel to carry "bankfull"
flows. The bankfull elevation is the point at which stream
flows begin to move out onto a floodplain. Bankfull flows
are smaller storm flows which occur on the frequency between
1.2 and 1.8 years. Over the long term it is the bankfull
storm flows that are responsible for maintaining natural
channel conditions. These smaller channels are able to
transport sediment and provide good aquatic habitat. |
 
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Additional information on this topic provided below. |
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raditional
engineered channels are designed to carry very large storm flows
and as such are very large and wide. Initially these over designed
channels are capable of carrying large flows but over time accumulate
sediment. Sediment deposition occurs in these channel due to
the smaller storm flows. When sediment moving downstream passes
through these large channels, the energy is distributed across
the channel and the sediment drops out. Over time this sediment
builds and requires regular maintenance to maintain the desired
design capacity.
here
are many different rock and log structures used in natural channel
restoration projects to help stabilize stream banks and help
maintain the proper, natural features. Rock vanes, cross rock
vanes, "J" hook rock vanes and root wads. In addition
to improved sediment transport and channel stabilization, these
structures also provide aquatic habitat. |
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