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DELAWARE RIVER BASIN COMMISSION
Examples
| ALIGNMENT:
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By nature, through its many complex physical laws, streams meander.
When meanders are removed by straightening, streams tend to erode
to its former meander form. |
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| EROSION: |
Severely eroding streambanks, a common occurrence in both urbanizing
and agricultural regions, causes disruption of upland property,
loss of streamside vegetation, and increased sedimentation. |
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| LOW FLOW: |
Unnaturally low stream flows, a common occurrence in urbanizing
regions, deteriorate the aquatic habitat. Less obvious is the loss
of streamside habitat, as plant root zones are deprived of adequate
life-supporting, soil-saturating moisture during dry spells. |
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| SCOUR: |
Stream scouring threatens infrastructure, often requiring costly
structural protection and/or replacement. Maintaining a stream in
a more stable condition would lessen such costs. |
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| SEDIMENT: |
Excessive sediment smothers benthic life, a key link for a healthy
food chain. Loss of reservoir storage is accelerated. Turbidity
becomes more pronounced in wet weather flows. |
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| STORMWATER:
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Increased stormwater runoff to streams due to urbanization and
other factors, increases flood frequency and flow. This is a major
factor in loss of stream stability. |
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OTHER
EXAMPLES: |
In addition to the above examples, other factors impacting stream
stability include stream loss of contact with its former floodplain,
hydrologic alteration caused by dams, and excessive stream clearing
after damaging floods. A complete list would be quite extensive.
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| RESTORATION: |
The literature reporting on techniques for full stream restoration
is proliferating. Expensive, at approximately $30 to $300 per linear
foot for small to medium sized (first and second order) streams,
these reconstruction techniques need to be applied judiciously.
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