During the 20 th century, thematic maps have been an ever useful tool for correlating data sets and representing relevant information. Recent technological advances in computing, observational data collection, and spacial referencing, have lead to the advent of Geographic Information Systems (GIS), which is becoming an ever powerful and applicable tool for today’s professionals. ES 341 is an entry level GIS class intended to familiarize students with the concepts and usage of geographic information systems in real world applications to watershed analysis. The watershed under discussion here is the lower portion of the Siletz River, located primarily in Lincoln County, Oregon. Draining just over 300 square kilometers of area, covering a multitude of terrain, bedrock, and morphological features, it is an excellent representation of coastal watersheds. Specifically for our project we were tasked with creating maps presenting; watershed coverage, area soils, road ways, bedrock geologic features, vegetation, physiographic elevation models, and annual precipitation. Demonstration of Applied Exercises in Geographic Information Systems Lower Siletz River, Oregon Watershed, Sub-basin, & USGS Quads USGS 7.5 Min DRG Topographic Maps Streams & Vegetation INTRODUCTION Richard Fletcher, Patrick Stephenson, Earth Science Majors, Western Oregon University, Monmouth, OR, Digital Elevation Models Digital Ortophohoto Quads Contour Lines, Roads & Bedrock Geology This poster presentation is intended to be a final product showcase of the practical application of geographic information systems as it pertains towards earth science. GIS will become an ever increasingly useful tool by increasing understanding through graphical representation and comparisons of statistical and tabular data sets. SUMMARY REFERENCES Description: This map depicts the Lower Siletz Water Shed and the eleven 7.5 minute quadrangles that are related. Description: There are three primary vegetative covers. Dominantly covered by Stika spruce and western hemlock, the Lower Siletz Watershed is also covered by Douglas Fir, Grand Fir, and Mixed Conifer trees. This variety in vegetative covers may be due to the relative change in elevation as well as temporal coverage from North to South. Description: The watershed is included in seven USGS 7.5 minute topographic maps. From East to West the watersheds gradient changes drastically from steep and dissected in the east to a far more gentle meandering system on the west. Description: Digital Elevation Models are extremely useful in analyzing watershed gradient. These models can show relief in different color schemes for different uses. This model, for instance, could be used in hazard assessment of land slides and flooding within the Lower Siletz Watershed. Description: Above is a map depicting the bed rock geology with reference to roads and topography within the Lower Siltez Watershed. The geology observed at the surface is primarily visible due to the erosive properties the steams and rivers have worked into the land over long periods of time. Description: These Digital Orthophoto Quads (DOQs) are georectified 7.5 minute, 10 meter resolution aerial photos with a spatially referenced outline of the Lower Siletz Watershed. SourceData DOQ Streams, Watershed Table 1: Lower Siletz River Watershed Measurements StatisticValue Minimum Watershed Elevation8.5 ft Maximum Watershed Elevation2828 ft Minimum Slope0 ۫0 ۫ Maximum Slope62 ۫ Table 2: Elevation Analysis USDA Soil Survey Description: There are forty-five unique soil types in the Lower Siletz Watershed. These soil types are unique to the slope gradients and the flow type of the water. Many of the soils within this watershed are unconsolidated and are unstable due to steep gradients and high annual precipitation. Annual Precipitation & Elevation Description: Annual precipitation rates fluctuate within the Lower Siletz Watershed. The map made above is a vector based model expressing the igher and lower accumulation amounts annually. ES 341: Fundamentals of GIS Total Drainage Area (sq. meters)309,762, Square m Total Drainage Area (sq. kilometers) Square km Total Length of Watershed (km)30,000 m, 30 km Total Width of Watershed13,500 m, 13.5 km Length to width ratio2.222 Total No. of Sub-basins in watershed18 Average area of sub-basins in watershed17,209,014 m 2, km 2 Total No. of Steam Segments2330 Total No. of 1 st Order Streams1,172 Total No. of Second Order Streams504 First Order Stream Frequency4.14 (1 st order / km 2 ) Lower Siletz River