Lower Siuslaw River Watershed
Lane and Douglas Counties, Oregon
Tim Lundy and Joey Doyle, Western Oregon University
Introduction
The purpose of this poster is to represent several
interesting facts as well as provide different map
styles to show different themes of the Lower Siuslaw
Watershed. The map themes include USGS Digital
Raster Graphics(DRG), USGS Digital Elevation
Models(DEM), Bedrock Geology, Annual Rainfall/
Precipitation, soils, Vegetation, Roads, Streams,
Digital Orthophoto Quadrangles (DOQ), and
Wetlands.
Location
The Lower Siuslaw Watershed is a subbasin of the
larger Siuslaw Watershed and is located in Northwest
Oregon in Lane and Douglas counties. It covers parts
of the Mercer Lake, Tiernan, Mapleton, Greenleaf,
Goose Pasture, Florence, Goodwin Peak, Baldy
Mountain, and Roman Nose Mountain quadrangles.
Digital Raster Graphics (DRG)
Digital Elevation Model (DEM)
Digital Orthophoto Quadrangles (DOQ)
Watershed perimeter overlaying digitized standard 7.5 minute quadrangles.
Elevation data is stored in each pixel and can be colored or shaded to convey
information; e.g. absolute heights, slope angle, or to emulate physical structure.
This DEM is at 10 meter resolution .
Georectified aerial photographs by quadrangle.
Physiography, Geology, and Hydrology
The underlying geology is almost entirely layered
marine sandstones, known as the Tyee Formation.
This is a soft, erodable rock that, when combined
with the high seasonal rainfall and steep slopes is
subject to landslides known as "debris flows". The
overall shape of the land, with relatively level but
narrow valleys flanked by steep low mountains with
knife-edge ridges, is a result of this interaction. The
Coast Range is still actively rising, but the main
streams have the power to carve out low-gradient
paths through the mountains to the sea. The Siuslaw
is one of only a few rivers that has managed to cut a
path
entirely
through
the
coast
range.
(http://www.inforain.org/siuslaw/)
Watershed Statistics
Total Drainage Area
445.5 km2 (445466105 m2)
Length of watershed
21.2 km
Width of Watershed
41.1 km
Length/Width ratio
0.515
No. of Sub-basins in Watershed
22
Average Area of Sub-basins
20.2 km2
Total No. of Stream Segments or Tributaries
3407
Total No. of First Order Stream Segments
1758
Total No of Second Order Stream Segments
806
First Order Stream Frequency
3.9 per km2
Soils
Geology
Climate
Soil distribution throughout the Lower Siuslaw Watershed.
Bedrock types with roads overlay.
Average precipitation shown in inches per year with streams overlay. Heavier
rainfall shown in purple, lighter in orange. Streams classified and sized by order.
Resources
DEM and DOQ
http://libweb.uoregon.edu/map/map_section/search.html
DRG
http://libremap.org/data/state/oregon/drg/
Precipitation Data
http://prism.oregonstate.edu/
Soil Data
http://www.or.nrcs.usda.gov/pnw_soil/or_data.html
Streams Data
http://www.wou.edu/las/physci/taylor/es341/coast_streams.zip
Elevation and Slope
Minimum Watershed Elevation
0 ft (sea level)
Maximum Watershed Elevation
712.5 ft
Minimum Slope
Maximum Slope
0°
68.1978°
Watershed Data
http://www.wou.edu/las/physci/taylor/es341/coast_sheds.zip
Vegetation
Streams and Subwatersheds
Types of flora, dune areas, urban development, and open water are represented.
Watershed drainages and associated streams are shown. Drainage boundaries
in yellow; streams classified and sized by order.
Geologic Data
http://tin.er.usgs.gov/geology/state/state.php?state=OR
Vegetation data
http://www.oregon.gov/DAS/EISPD/GEO/alphalist.shtml