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Streams
and Watersheds - Introduction
Method
4 = In relation to their shape
A fourth way
to classify streams, one which is often used by federal and state
land management agencies, is known as the "Rosgen classification"
or the channel shape method. This approach categorizes streams on
the basis of their slope (steepness), sinuosity (meander pattern),
ratio of the stream's width to its depth, degree of entrenchment,
and soil particle size (texture) of the streambanks and channel
bottom. The Rosgen method is useful because it can provide hints
about what type of management activities may be best suited for
a given stream.
Key
Point
Regardless
of the system of classification used, the key point to remember
is that streams both reflect and shape the landscape where
they are located. For example, a steep, rocky, mountainous
channel with only a narrow riparian area would respond differently
to a sudden increase in water volume than would a low gradient
channel meandering across a wide floodplain.
Land managers
and operators must work with their streams, not against them.For
example, to transplant beavers into a steep gradient, narrowly
confined stream to stabilize the channel would not be very
effective because any dams they constructed would likely be
blown out during high flows. On the other hand, in an appropriate
system beavers can play a very effective role in enhancing
water storage in the soil and in the ponded channel. This
can increase forage production beside low gradient, meandering
channels which cross flat meadows (Fig. 1-5).
To understand
better the need to work with the particular streams you have
on your property, let's look briefly at how streams operate.
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Figure
1-5
The flat
gradient along this foothill valley stream allowed the establishment
of beaver dams, which are affecting the hydrology of the meadow. |
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