General Approach to Bank Stabilization
Beyond the altruism of economic sensitivity, most river engineering and management
agencies are now more attentive to non-traditional methods for quantifying the economic
benefits of environmentally preferable alternatives.
4.2.2.2 Opportunities and Hazards
Greater opportunities for creativity and innovation exist in the environmental aspects
of riverbank stabilization than in the more obvious and traditional aspects of river science and
engineering. A creative attitude can be catalyzed by recognizing environmental considerations
as worthwhile challenges and opportunities, rather than as burdensome requirements,
although this attitude may be difficult to maintain in the face of pressing schedules and
funding constraints. The task is made easier, and goals are achieved more effectively, by
addressing environmental concerns as early in the planning process as possible.
Although riverbank stabilization does not have the dramatic environmental impact of
reservoir construction or channelization of rivers, significant environmental hazards and
opportunities do exist. An important distinction, between channelization and stabilization,
must be made here, so that perception of the former does not unjustly condemn the latter.
The distinction is often overlooked by the public, and is sometimes blurred in the literature.
Channelization implies significant alteration of long reaches of a stream, often to the detriment
of channel stability and environmental quality, whereas bank stabilization often provides
environmental benefits, as discussed in 5.2.
All riverbank stabilization projects impact the environment, regardless of the means
used to stabilize the channel (Henderson and Shields, 1984). Some potential impacts are:
Flood plain development or increased agricultural activity may be induced
when the threat of channel migration is reduced or removed.
Eroding bank habitat, which is more valuable ecologically than one might
think, will be reduced, and the growth of bars and successional vegetation will
be altered, perhaps at the expense of habitat diversity. Bed material
composition, flow distribution, and other in-channel habitat factors may also
be affected.
The formation of ecologically valuable abandoned channels ("oxbows") will
be prevented, a serious consequence since existing oxbows usually deteriorate
with age due to sedimentation.
Some types of maintenance activities may discourage the reestablishment of
natural conditions after the project is complete.
The river scientist's task is to recognize the potential impacts, and then to minimize
the bad and maximize the good.
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