A stream confinement layer was not
available for the entire study area. Therefore, we used
the
DEMs to derived a
stream confinement layer using ARCView.
First, we used the DEMs to derive a
slope
layer in which flat areas were separated from steep areas.
After several trials, we considered slopes between 0-5 degrees
to represent 'flat areas' along stream beds (unconfined)
and slopes greater than 5 degrees to be steep areas (confined).
To remove 'salt & pepper', we removed small (<1.5
ha), isolated polygons depicting flat areas along streams.
Finally, we intersected the slope shapefile with the
DEM-derived
streams layer using ARCView. This resulted in a new
field (CONFINEMENT) within the derived streams coverage
describing the stream confinement.
We found that the majority of streams (75.4% of the total
length) were confined.
Keep in mind that the definition of stream confinement
depends on the relationship between actual stream width
and valley floor width. For the MidCoast region, this
information was generally lacking. Therefore, this representation
of stream confinement is meant to serve as a 'stand-in'
data layer until a better data layer is available.
We used these data for
stream
channel typing. This layer could also be used to target
restoration actions in unconfined, low gradient streams
A good use of this data layer would
be to guide field teams and to field verify where the layer
correctly represents stream confinement and where it does
not.
Please address questions or comments
to:
Dr. Ralph Garono
Principal Investigator
Earth Design Consultants, Inc.
rgarono@earthdesign.com
Laura Brophy
Principal Investigator
Green Point Consulting
brophyl@peak.org |
homepage 
