Here we examine the utility of using LIDAR DEMs to create a stream
profile in a heavily forested area. We are looking at the upper
part of Coal Creek near Newcastle east of Seattle (T23NR05E,SE quarter).
The first image is a 1990 and (right two-thirds) 1991 one-meter orthophoto
of the area, showing a 50-meter buffer around the stream.
Below is a detail of the previous image. Note that there was increased
urbanization between the orthophoto and LIDAR (2001?) dates, and that
LIDAR was flown after leafdrop.
The image below shows the stream profile derived from the 6-foot LIDAR DEM.
The places where "sinks" in the DEM were filled correspond, as expected,
to bridges or culverts.
but see that lidar provides too much information for the automated tracing
the Bogachiel River, especially by a tracing program that thinks it is clever.
The blueline is a USGS blueline, and the red line was defined by the infamous
proffix2.aml, which follows terrain downhill, even in filled "sinks".
The blueline, lidar, and orthophoto represent different years.
Harvey Greenberg . . . . .
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