http://hdl.handle.net/1957/7864 Collection contains recent scholarly output of student majors in the Department of Forest Engineering. Search the Channel search http://ir.library.oregonstate.edu/dspace/simple-search http://hdl.handle.net/1957/9430 Title: Influences of landslides, floods and land use on channel changes of the upper Middle Fork Willamette River, Oregon 1936-1980; Channel changes of the upper Middle Fork Willamette River, Oregon, 1936-1980 <br/> <br/>Abstract: Time trends in flow and channel characteristics were evaluated for the Middle Fork Willamette (MFW) River, which drains a 668 km2 forested watershed in the Cascade Mountains of western Oregon. Timber production is the primary land use in the watershed. Analysis of precipitation and peak flow data from 1959 to 1980 suggests that peak flows (greater than 0.15 m3skm2) increased 2% per year as timber harvesting and road building expanded in the basin. Landslides associated with roads and clearcuts, based on an inventory of aerial photographs dating from 1959 to 1972, were 27 and 23 times more frequent (respectively) than in forested situations. The majority of landslides appear to have been initiated during the relatively large flood of December 22, 1964. Changes in channel planform morphology from 1936 to 1980 were documented from aerial photographs. Based on the photographic record, channel width increased prior to 1967 followed by a decreasing trend from 1967 to 1980. Sixty-five channel cross-sectional profiles were surveyed during summer low flows in 1979 and 1980 to provide detailed measurements of existing channel conditions. The presence or absence of aggradational features was noted at each cross section. Regression analysis revealed that significantly greater (c= 0.05) channel widths were recorded for 62% of the aggraded reaches compared to the dimensions of nonaggraded reaches. The results of the cross-section surveys, combined with the channel morphology and landslide measurements, suggest three conclusions: (1) major aggradation along the NW River occurred during the 1964 flood, (2) landslides associated with the 1964 flood contributed to the development of aggraded locations along the river, and (3) the majority of landslides during this period occurred within one geologic zone and were associated with land use activities, thus suggesting management activities, particularly roads, influenced changes in channel morphology. <br/> <br/>Description: Graduation date: 1982; Presentation date: 1981-10-09 http://hdl.handle.net/1957/9396 Title: The effects of compaction on hydrologic properties of forest soils in the Sierra Nevada <br/> <br/>Abstract: This study evaluated the effects of a crawler tractor, a rubber-tired skidder, and a torsion suspension vehicle on several soil and hydrologic properties in the western Sierra Nevada Mountains of California. Four sites, with soil textural classes ranging from a loam to a loamy sand and elevations between 680 and 2180 m, were studied at three moisture contents. Compaction was monitored with a double probe nuclear densiometer and an air permeameter after 1, 3, 6, 10, 15, and 20 round trips. Density measurements were made at five different depths. Infiltration capacities were determined with a small, portable rainfall simulator. Soil core samples were taken to observe porosity and conductivity levels before and after disturbance. Compaction, or the change in bulk density, was significantly greater on the crawler tractor trails at all depths. When only the plots established in the outer positions of the trails were included, this distinction between vehicles could not be made. The crawler tractor generated more uniform compaction across its trails that either the torsion suspension vehicle or the rubber-tired skidder. The greatest change in bulk density for all the vehicles took place in the surface five centimeters. Infiltration capacities on the undisturbed sites were found to exceed predicted maximum precipitation rates. Mineral soil at the three higher elevation sites was very hydrophobic. This was thought to be due to the coating of soil particles with the metabolic products of fungal mycelia. The crawler tractor reduced infiltration capacities by 78 percent, while the torsion suspension vehicle and the rubber-tired skidder caused 67 percent decreases. Suspended sediment concentrations determined from runoff collected on the infiltration plots served as an erosion index for the skid trails. The crawler tractor trails had runoff with 40 percent higher sediment loads than that found on the trails of the other two skidders. Organic matter content was inversely correlated with the sediment levels. Air permeability readings showed that the three vehicles produced very similar reductions in macroporosity in the surface 2.5 cm layer as the number of trips increased. Approximately 75 percent of the decrease in macropore space occurred by six trips. The air permeameter provided a relatively good index of compaction. Porosity and conductivity levels determined from the soil core samples showed that machine differences did not exist in the track position. Macropore space was r2duced 43 percent and the conductivity decreased 80 percent. Site differences were much more evident than vehicle differences. Observations made after one over-wintering period showed that measureable recovery had not occurred. <br/> <br/>Description: Graduation date: 1981; Presentation date: 1980-12-12 http://hdl.handle.net/1957/9395 Title: Wind direction and effect of tree lean on coarse woody debris production <br/> <br/>Abstract: The natural fall of trees in riparian areas is an important source of coarse woody debris for mountain streams, improving fish habitat and influencing stream morphology. Existing models consider the probability of coarse woody debris entering a stream channel based upon trees having a random direction of fall without consideration of tree lean or wind direction. This research presents (1) the results of a field study to document tree lean of conifers near streams in two stands in the Oregon's Coast Range and (2) a physical and probabilistic model to estimate the probability of a tree falling into the stream including the effects of tree lean and wind direction. The measurement of 200 conifers along two creeks located in McDonald Forest found that tree lean varied from 1 to 34 percent uphill and 1 to 29 percent downhill on slopes of 1 to 88 percent. Approximately 75 percent of the trees leaned downhill and 25 percent of the trees leaned uphill. A significant linear relationship was found between lean and slope although there was considerable scatter around the regression line. In general, the steeper the slope, the greater the tree lean downhill. When tree lean data was stratified by aspect, the linear relationship was higher for the NE and SW aspects, slightly weaker for the NW aspect and not related with slope for the SE aspect. A physical model was developed for calculating the critical wind speed required to overturn a tree. This critical wind speed is a function of maximum resisting moment of the tree root structure, crown cross sectional area, initial tree lean and the angle formed between wind direction and lean direction on the horizontal plane. A probabilistic model was developed for determining the probability that a tree could fall and reach the stream. This probability is a function of exceedance probability for a particular period of time, wind direction probability, tree location and tree height. The models were applied to two old-growth coniferous stands. Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] trees were selected to illustrate how the models can be used. Results of this study indicate that tree lean is not a major factor with respect to influencing tree blowdown for the range of tree lean data collected from coniferous trees along streams in the study area. Tree lean could be a major factor if it was greater than that observed in this study. <br/> <br/>Description: Graduation date: 1995; Presentation date: 1994-06-06 http://hdl.handle.net/1957/9394 Title: Controlling water temperatures with buffer strips <br/> <br/>Abstract: Buffer strips have been proposed as a method for controlling temperature changes in streams adjacent to clear-cuttings. Nine small mountain streams in Oregon's Coast Range and Cascade Mountains were studied to determine the influence of buffer strips on water temperature. Timber volume in the strip, strip width, and canopy density perpendicular to the sun's rays were compared to the effectiveness of the strip in controlling temperature change. This effectiveness was not well correlated with timber volume or strip width. The density of the canopy in the path of the sun is the most important buffer strip characteristic for water temperature control. A method for measuring the density of the canopy in the path of the sun is described. The use of this method in the design of buffer strips will provide protection for the stream and maximum harvesting of the timber resource. <br/> <br/>Description: Graduation date: 1973; Presentation date: 1972-06-06