Introduction This project demonstrates the many components of working with ArcView GIS software. Compiled is a complete set of GIS vector map themes, Digital Elevation Models (DEMS), Digital Raster Graphics (DRGs) and other GIS data for Gale Creek Watershed. Watershed Location Gale Creek Watershed is located in the northwestern corner of Oregon and is contained almost completely in Washington County. It is one of many large watersheds in the Tualatin River Basin. It is situated on the eastern side of the Coast Range Mountains. General Geology The oldest geologic materials in the Gales Creek Watershed and volcanic and sedimentary rocks formed during the Eocene and Oligocene ages of the Tertiary period. The volcanic rocks and mostly basaltic lavas and tufts, overlain by sedimentary rocks made up of shale, claystone, sandstone, and siltstone. There are 11 soil associations listed in the Natural Resources Concervation Service (NRCS) Soil Survey of Washington County. Soils in the Coast Range are well-drained silt loam and cobbly loam. The nearly level flood plains consists of young alluvium, silt, and clay deposits approximately 20 to 30 feet thick. The historic wetland areas have eight hydric soil types which are generally very deep, poorly drained, and have slow surface runoff. The entire watershed is underlain by sandstone 400 feet thick (Breuner). Hydrologic Summary The watershed has 10 subbasins and contains 17 tributaries. Streams are fed primarily by precipitation. Most streams in the low lying parts of the watershed have been channelized and wetland areas have been drained for agriculture use. Conclusions This project focused on finding and displaying various GIS data for Gales Creek Watershed. It included assembling DRG, DEM, DOQ, bedrock geology, precipitation, soils, vegetation (timber), streams and road themes in the form of our particular watershed. References Cited Breuner, Nancy. (1998). Gales Creek Watershed Assessment Project. Tualatin River Watershed Council. Gale Creek Watershed in Washington County, Oregon Prepared by: Pamela Monnette ES 492: GIS Applications in Earth Science The figure on the right represents the types of Timber in Gales Creek Watershed with the streams in the area overlain on top of it. Physiography The watershed ranges in elevation from a low of 159 ft. above sea level, at the confluence with the Tualatin River, to its highest point of 3,154 ft. The mainstem of Gales Creek is 23.5 miles long and flows in a southeasterly direction. Land designations promote the rural character of the watershed by limiting land uses to forestry, agriculture, scattered rural residences, and rural services. Almost two-thirds of the watershed is privately owned (Breuner). Timber and Vegetation The watershed contains a mosaic of native and exotic plant species. The original forested uplands, most of which was logged 40 to 80 years ago or burned in two stand- replacing fires in 1933 and 1945, known as the Tillamook Burn, have been replaced with Douglas-fir forests which are intensively managed. Furthermore, black cottonwood, bigleaf maple, Oregon ash, vine maple and elderberry are the dominant plant species in the riparian zone of Gales Creek (Breuner). The watershed is entirely within the Northwestern edge of Washington County, except for 2 small portions extending into Tillamook County. On the left is a Digital Elevation Model of all of the Quads that make up Gales Creek Watershed. The darker areas represent higher elevations, while the lighter areas represent lower elevations. DEMs Digital Orthophotos of Gales Creek Watershed Quadrangels DOQs Here we see an image of digital raster graphics with an outline of the Gales Creek Watershed boundary overlain on top of the quads. and DRGs! Climate The climate with the watershed is marine-influence with an extended winter rainy season. Summers tend to be hot and dry with little rainfall. The Coast Range Mountains form the upper north and Western boundaries of the watershed, separating it from the Pacific Ocean to the west. The mountain slopes tend to be steep with high gradient streams. This figure was achieved By clipping a larger stream network to the area of the Quadrangles that Gales Creek Watershed resides in. This is a figure displaying the precipitation in inches annually received in Gales Creek Watershed. Above is a figure showing the distribution of bedrock Geology within Gales Creek Watershed. The colors Are represented by codes that correspond to different Types of rock. Overlain onto this theme, is a map of Major highways. Gales Creek Pictures