WWRC 85-44
The Use of Meander Parameters in Restoring Hydrologic Balance to Reclaimed Stream Beds
Introduction
A river or stream is dynamic through time. Change is one of the most common
features associated with river and stream channels. In general, this change is very
slow, however, and only over long periods of time is it actually noticeable to
most individuals. As a result, engineers, ecologists, and others involved with the
hydrologic balance of a stream many times treat the stream system as static (i.e.
unchanging in shape, slope, or pattern). One only has to observe a favorite fishing
stream or pleasure area along a stream to notice that the stream channel itself
probably looks slightly different now than it did two or three years previous.
In general, most streams are continually changing position and shape as a
consequence of hydraulic forces acting on their beds and banks. This stress is
mainly a result of climatic changes from year to year in the amount of water
flow variation that occurs in the stream. Over time, the stream system adjusts to
this natural variation in flow and develops a pattern which puts the system in a
quasi-steady, yet dynamic, situation where only unusual climatic events or human
activities may cause rapid changes in the nature of the stream channel morphology
(dimensions, shape, or pattern). It should be noted, however, that streams are,
in fact, the most actively changing of all geomorphic forms, especially alluvial
stream systems. It is the rule rather than the exception that banks will erode,
sediments will be deposited, and floodplains, islands, etc., will undergo change
with time (Richardson et al. 1975). The problem in all this comes when humans
induce change upon the system without taking the necessary steps to restore the
quasi-steady situation and thus set in motion a response by the stream system to
adjust to this change, which results in the propagated response along great distances
from the human-induced action.
In planning and designing stream channel restoration and stream system
balance, it is critically important to avoid the geometric stress thresholds of a
stream at which dramatic and significant undesirable landscape modifications occur.
It is desirable to approximate a range of appropriate stream channel features that
will cause the stream system to respond to its natural inclinations (the stream
pattern which would exist under normal conditions) as if no human action had
occurred. This intervention will result in controlled sediment production and produce
a channel similar to the existing stream channel. The end result will be a
system where stream habitat should be equivalent to predisturbance and, hopefully,
a slight enhancement of habitat and form.
This chapter discusses methods and techniques for restoring a stream channel
to its natural inclinations after a human-induced change such as surface mining,
road construction, etc. The main emphasis will be on meander parameters and
their importance in stream channel stability.
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