Many types of spatial analyses require data that are
of consistent scale. Furthermore, in order to set restoration
and monitoring priorities on a site-by-site basis, it
is best to have uniform datasets that extend across the
entire area of concern. We are conducting an analysis
for the entire MidCoast region of Oregon at a spatial
scale of 1:24,000. Until recently, a digital streams layer
did not exist that was at an appropriate spatial scale.
A
densified streams layer
containing important information on stream channel confinement,
stream gradient and fish distribution has been developed
by USFS (Siuslaw National Forest) specifically for the
MCWC study; however, this data layer was created by combining
streams data collected by different methods at different
spatial scales.
To generate a streams layer, we used an ARCView extension
(txdo0409.apr) developed by David Maidment's group at the
University of Texas, Austin. The extension is available
on the WWRI web site (
http://www.ce.utexas.
edu/prof/maidment/) or on the Hydro98 CD-ROM (available
from Environmental Systems Research Institute, Inc. (ESRI)).
We used a Stream Initiation Threshold of 1400 cells
(about 34 acres). This resulted in the generation
of 6,293.8 km of stream that cover the entire study area.
This approximates the
USGS 1:24K
streams network.
We used this layer to summarize instream
data. These data are expressed as stream length in each
channel type category.
This is a uniform scale data set that is consistent with
other DEM-Derived layers, i.e., confinement, gradient,
etc.
See stream density,
confinement,
and stream
gradient.
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 |
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