introduction
DESCRIPTION
North Yamhill River Watershed – Yamhill & Washington County, Oregon. Prepared by: Courtney A. Stowell ES 492. INTRODUCTION - PowerPoint PPT PresentationTRANSCRIPT
INTRODUCTION
The North Yamhill River watershed consists of 445 miles of waterways and covers 113,441 acres (177 square miles), almost entirely in Yamhill County, Oregon. There is a small part of the watershed that is located in Washington County. (See figure 2)
Watershed Location
The North Yamhill River starts in the eastern side of the Coast Range, flowing south and east to its convergence with the Yamhill River, just southeast of McMinnville. (See figure 1) The Yamhill River then drains into the Willamette River near Dayton.
General Geology
The General Geology (Bedrock) of the North Yamhill River Watershed consists of mainly is Quaternary Sediment (Qs), Siletz River Volcanics (Tsr), and the Yamhill formation consisting of marine sedimentary rocks (Ty). The main soils of this watershed correspond with the bedrock. So Qs has silty valley soil whereas Tsr and Ty are more rocky soils (cobbly and stoney) found on hillslopes. (See figures 3 & 4).
Hydrologic Summary
The North Yamhill River consists of the following major tributaries: Panther Creek, Baker Creek, Haskins Creek, Fairchild Creek, Yamhill Creek, and Turner Creek. (See figure 10) Stream flow in the North Yamhill watershed varies throughout the year, largely depending on the amount of rainfall. (See figure 11) The high and low flows have different impacts on the landscape and resources. The total drainage area is 457,275 sq. km. The length of the watershed is 29 km and the width is 18.5 km. Some other facts include: total number of streams – 2162, first order streams – 1096, and second order streams – 510.
Conclusions
• The North Yamhill River watershed is unusual, as it encompasses two counties: Yamhill and Washington.
• The watershed is sub-divided into 24 sub-basins with an average area 19053 sq. km.
• The Geology consists of 3 major bedrocks: Qs, Tsr, and Ty with certain soil characteristics associated with each.
• There are two major vegetation groups: Douglas Fir and Oak-Douglas Fir.• Stream discharge is highly precipitation controlled in the North Yamhill
watershed. Stream flow parallels precipitation throughout the year.
References Cited
Schmit, L. Denise. "2005 Interim Report - North Yamhill River subwatershed." Yamhill Basin Council 2005 8-9. 21 Mar 2007 <http://www.co.yamhill.or.us/ybc/Monitoring/Interim2005WQMPreportFINAL.pdf>.
North Yamhill River Watershed – Yamhill & Washington County, Oregon
Prepared by: Courtney A. Stowell
ES 492
Physiography
Most of the land in the Yamhill Watershed is privately owned (approximately 87%), with the majority of land uses in agriculture (60%) and industrial forestry (37%). Although the predominant land uses in the North Yamhill River Watershed are agriculture and forestry, urban areas are growing rapidly. The elevation ranges from approximately 50 feet to 1050 feet. (See figures below)Maximum Elevation – 1043 feetMinimum Elevation – 20 feetMaximum Slope – 66.21Minimum Slope – 0
Figure 1 – Map of Oregon & North Yamhill River watershed
Figure 2 – Counties watershed encompasses
Figure 5 - DEMs
Figure 7 - DRGs
Figure 6 - DOQs
Figure 8 – Vegetation
Notice in the figure above that most of the vegetation
consists of Douglas Fir.
Figure 9 – Precipitation
Annual Rainfall - Climate Map
Figure 3 – Geology (Bedrock)
Figure 4 – Soil Map
There are many different types of soils in the North Yamhill
River Watershed
Physiography Continued
Figure 6 displays vegetation and the most abundant kind is Douglas Fir and Oak-Douglas Fir. The Annual Rainfall for this particular watershed ranges from 40-120 inches inches per year. The figures below consists of: Vegetation Map and Annual Rainfall Map. (See figures 8 & 9)
Figure 10 - Streams
Figure 11 – Streams on Precipitation