and Watersheds - Importance
of a Watershed Perspective
The sinuous pattern of this valley bottom illustrates
how stream channels shift over time.
the watershed may cover a large area, what happens in one part of
the watershed may have both direct and indirect effects on other
portions. For example, installation of an irrigation diversion in
the upper portion of the watershed may result in a reduction in
the amount of water which moves through the channel further downstream.
This could change the type of vegetation that can grow in riparian
areas in lower portions of the watershed.
a timber harvest in the upper part of the watershed may result in
more water flowing into the channel over a shorter period of time
because less is being used by large, deep-rooted woody vegetation.
The result could be higher overbank flooding in some years or increased
lateral or vertical cutting because the increased volume of flow
places additional pressure on streambanks and the channel bottom.
On the other
hand, what happens along the stream can affect the uplands. Suppose
you wished to improve the vegetation on streambanks in a riparian
area. One way to do this would be to manage livestock use of the
riparian portions of the pasture. Pushing stock out of the riparian
area means they will spend more time in the uplands.
result will be better use of all forage resources in that pasture.
At the same time, this increased use of upland forage may affect
other management considerations. For example, if these upland areas
are providing winter range for elk and maintaining this herd is
one of your objectives, your stocking rate considerations should
also include elk use levels.
are the link between the uplands and the stream. Different types
of streams affect riparian areas differently, just as the presence
of different riparian vegetation influences the nature of its related
the different types of streams you may encounter and being able
to recognize how they interact with their riparian areas will enable
you to make more effective management decisions.