Side slope sedimentation following new work dredging on the Lower Columbia River, Oregon and Washington
Year: 1989
Type: dissertation
Abstract: Side slope sedimentation from navigation channel side slopes following "new worktt dredging (increased channel dimensions) is a large, but short-term, contributor to bedload sedimentation on the Lower Columbia River.Prediction of rates and volumes of increased sedimentation can be used to forecast maintenance dredging requirements following new work dredging events.Side slope sedimentation decreases exponentially with time, reaching equilibrium conditions in 3 to 6 years.INFIL was designed to construct an exponential decay curve that distributes annual side slope sedimentation over the readjustment period.INFIL was calibrated by adjusting input variables to match historic records of side slope sedimentation following new work dredging at six study sites.Calibration results show that percentages of total side slope sedimentation during the first year of the readjustment period are sensitive to both the length of the readjustment period and the depth of the dredging excavation.However, they tend to ignore the recent geology, or lump younger deposits into "recent alluviumn consisting of undifferentiated gravel, sand, silt, and clay.The geolcgic materials of concern in this study are the Holocene and Pleistocene alluvial sediments.Some data on the younger sediment fill are given by riffi in and others (1959) , Mundorf f (1964) , Hogensen and Foxworthy (1965) , and Hoffstetter (1984).All of these reports provide aquifer descriptions and cross-sections in the Portland-Vancouver area.These data are supplemented by borehole descriptions and cross-sections obtained from unpublished material from CH2M Hill (1971, 1974) and the U.S. Geological Survey (1984) for the East Portland area.Very little information has been published about the depth or areal extent of the recent alluvial materials located downstream of the Portland-Vancouver area.Various drainage district design memoranda from the Portland District, Corps of Engineers (U.S. Army Corps of Engineers, 1957aEngineers, , 1957bEngineers, , 1957cEngineers, , 1959Engineers, , 1960aEngineers, , 1960b)), estimate the depths, distribution and general materials units contained in the Columbia River flood control drainage districts.The only well logs that have been evaluated for this study are those published in Mundorff's report (1964).
Author: Sarah J Babcock
Institution: San Jose State University
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: gold
OpenAlex ID: W4234855747