GIS Data Management for Watersheds in Western Oregon
Gales Creek Watershed, Washington County, Oregon
Kelsii Dana & Ricci Keller, Earth Science Majors, Western Oregon University, Monmouth, OR
ES 341 Fundamentals of GIS
USGS Quads
Digital Elevation Models
Digital Orthophoto Quads
Description: Elevation of the Gales Creek Watershed ranges from 159 to 3,154
feet above sea level. The Watershed is 39.4 km in length and 13.6 km wide. Water
flows in a southeasterly pattern out of the watershed. Some features within the
watershed include Round Top, which is 2,986 feet high and Gales Peak, which is
1,800 feet high. Gales Creek Watershed gets an annual rainfall of 45 to 110 inches
depending on the elevation within the water shed.
Description: A Digital Orthophoto Quadrangle (DOQ) is a uniform-scale image
created from aerial photos. Relief displacements caused by the camera and terrain
have been removed, and ground features are displayed in their true position. A
DOQ combines the characteristics of a photograph with the geometric qualities of a
map, allowing direct measurements of distances, areas, angles, and positions.
WATERSHED MEASUREMENTS
Statistic
Value
Total Drainage Area (sq. m)
244,243,408
Total Drainage Area (sq. km)
244
Total Length of Watershed (km)
39.4
Total Width of Watershed (km)
13.6
Length to width ratio
3:1
Total No. of Subbasins in watershed
10
Average area of sub-basins in
watershed (sq. km)
24,400,000
Total No. of Stream Segments
1,513
Total No. of 1st Order Streams
765
Total No. of Second Order Streams
363
First Order Stream Frequency
76.5/Drainage Area
Description: Gales Creek Watershed is located in NW Oregon and almost
completely contained by Washington County. This watershed is one of ten
subbasins of the Tualatin Basin and is located to the east of the Coast Range.
ELEVATION ANALYSIS
Statistic
Value
Minimum Watershed Elevation
159
Maximum Watershed Elevation
3154
Minimum Slope
0
Maximum Slope
80.21
Annual Precipitation
Vegetation
Table 2: Elevation Analysis
Description: Oregon Climate is generally temperate with noted regional variations.
Because of its location, Gales Creek Watershed receives abundant precipitation of
varying. Average rainfall for Oregon is about 40 inches per year. Parts of this region
can receive up to 100 inches per year.
Geology
Description: Forested areas of Gales Creek Watershed vary with regards to the
dominant type of trees found. Douglas Fir Trees can be found throughout the
entire region along with Oregon White Oak, Western Hemlock, and Grand Fir.
Areas with recent timber harvest have localized mid elevation shrubbery present.
Remaining land use of the area is credited to highly developed urbanization and
agricultural cropland.
USDA Soil Survey
Streams
REFERENCES
Source
Data
http://tahoe.usgs.gov/DOQ.html
DOQ
http://libremap.org/data/state/oregon/drg/
DRG
http://libweb.uoregon.edu/map/map_section/quad_list.htm
DEM
http://www.or.nrcs.usda.gov/pnw_soil/or_data.html
Soil
http://sagemap.wr.usgs.gov/
Precipitation
http://tin.er.usgs.gov/geology/state/state.php?state=OR
http://www.wou.edu/las/physci/taylor/es341/es341_w09.htm
Geology
Vegetation, Wetlands
kdana06@wou.edu, rkeller06@wou.edu
Description: Geology within the Gales Creek Watershed consists mostly of marine
sand and siltstones that originate form the Eocene and Oligocene time eras.
Multiple formations can be identified in the region and include: the Cowlitz, the
Yamhill, Tillamook volcanics and various other volcanic intrusions made up
primarily of gabbro and basalt.
Description: Soils of Gales Creek Watershed contain mostly silty loam with
varying slope degrees. These type of soil deposits are commonly known to be
deposited from the Missoula Floods. Silty loam, with some alluvial deposits, makes
for very permeable land, hence the abundance of watershed basins in the area.
Description: The watershed has 10 subbasins and contains 1513 tributaries.
Streams are fed primarily by precipitation. Most streams are channelized and
wetlands in the area are used primarily for agriculture.