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Kilchis Watershed of Tillamook County, OR
Prepared by:
Spencer Helwig &Trevor Brown
ES 341
Introduction
The Kilchis Watershed is an important watershed that is mostly driven by
the Kilchis River which flows West into the Tillamook Bay. The Kilchis Watershed
is composed of 13 subbasins.
Physiography
The landscape present in the Kilchis watershed is mountainous terrain in the
Coast Range, with the Kilchis River being the defining characteristic of the
watershed. The watershed has a minimum watershed elevation of three feet and
a maximum watershed elevation of 1,006 feet. The minimum slope is 0 decimal
degrees and the maximum slope is 72.8 decimal degrees.
A variety of vegetation exists. The ones prominent existing are evergreen
forests, red alder forests, mixed conifer and deciduous forests, and agriculture.
This is reflected in the amount of rainfall the Kilchis Watershed receives over the
year on average, with the peak rainfall of 200 inches.
Hydrologic Summary
The Kilchis Watershed covers a total drainage area of 168,153.9 sq. km, total
width of 11.4km, and total length of 22.2km. The watershed is composed of 13
subbasins, and the average area of a subbasin covers 12.9 sq. km. The total
number of streams in the watershed is 1,171, with the number of first order
segments being 870 and the number of second order segments being 413. On
average, there is one first order stream for every five sq. km.
Watershed Location
The Kilchis Watershed is located North of Tillamook in Tillamook County, OR.
Minimum Elevation (feet)
Maximum Elevation (feet)
Minimum Slope (decimal degrees)
Maximum Slope (decimal degrees)
General Geology
The Kilchis Watershed has 4 different surface deposits: Qal, Tsd, Ttv, and Ttvm.
The Qal geocode stands for river alluvium deposits of Holocene age, the Tsd
geocode stands for sedimentary rocks of Oligocene to upper Eocene age, the Ttv
geocode stands for Tillamook volcanic rocks of Eocene age, and the Ttvm
geocode stands for marine facies. The most common soil in the Kilchis
Watershed is the Necanicum-Ascar-Klootchie Complex with 60 to 90% slopes.
3
1006.2
0
72.8
Total Drainage Area (sq. meters)
168,153,
967
Total Drainage Area (sq. km)
168.1539
67
Total Length of Watershed (sq. km)
Total Width of Watershed (sq. km)
Total No. of Subbasins
Average Area of Subbasins (sq. km)
22.2296
11.375
13
12.93492
7
Total No. of Stream Segments or Tributaries
Total No. of First Order Stream Segments
Total No. of Second Order Stream Segments
First Order Stream Frequency (Total No. / Drainage
Area)
1,717
870
413
1/5 sq.
km
Conclusions
By examining the Kilchis Watershed, using ArcGIS, it becomes clear to
observe specific spatial information regarding it’s boundaries, subbasins,
vegetation, geology, roads, elevation, streams, wetlands, and precipitation in
regards to this specific area. More rainfall occurs in areas of higher elevation,
agriculture exists in the lowlands of the watershed which also happen to be
made up of alluvium deposits, and that the roads follow the waterways in the
watershed. The skills used in creating this poster include: the collection of GIS
data from online sources, defining and transforming projection systems,
clipping, dissolving, mosaicing, and displaying data, as well as problem solving
and data transfer.
References Cited
http://www.oregon.gov/DAS/EISPD/GEO/alphalist.shtml
http://www.or.nrcs.usda.gov/pnw_soil/or_data.html
http://libweb.uoregon.edu/map/map_section/search.html
http://www.co.tillamook.or.us/gov/gis/default.htm