Stream densities (km stream/ ha watershed) were calculated
using the
DEM-Derived
streams layer because this was the best available
uniform scale data set that covered the entire study area.
Stream densities were calculated by summing up the total
stream length for each 6th field watershed and then dividing
that length by the watershed's area.
The average stream density for the entire study area
was 0.017 km / ha. Interestingly, the average stream density
calculated with the
1:100K
layer for the entire study area was 0.008 km/ha, an order
of magnitude lower than the data presented here. The stream
density calculated from the
1:24K
USGS DLG data, where those data were available, was
0.02 km/ha, which was pretty close to the DEM-Derived
stream density. Finally, the stream densities calculated
using the
USFS Densified
streams layer was 0.41 km/ ha, a order of magnitude
greater than the data presented here.
This demonstrates that scale is important when selecting
data layers for analysis.
Stream density may be useful as a single
factor in a multifactor analysis.
Based on the frequency distribution
of 6th field watersheds, the range of variability of this
variable is small (see frequency distribution table to
the right). While there are a few watersheds that have
high and low stream densities, the majority fall in one
category. This suggest that stream density may not be an
important variable for prioritizing watersheds in the study
area.
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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