HR: 1340h
AN: OS23A-1534    [Abstracts]
TI: Morphological Implications of Oceanographic Measurements Acquired along a Mega-Transect at the Mouth of the Columbia River, USA
AU: * Moritz, H R
EM: hans.r.moritz@usace.army.mil
AF: U.S. Army Corps of Engineers, Portland District, P.O. Box 2946, Portland, OR 97208 United States
AU: Gelfenbaum, G R
EM: ggelfenbaum@usgs.gov
AF: US Geological Survey, 345 Middlefield Road MS 999, Menlo Park, CA 94025 United States
AU: Ruggiero, P
EM: pruggiero@usgs.gov
AF: US Geological Survey, 345 Middlefield Road MS 999, Menlo Park, CA 94025 United States
AB: During August-September 2005, an intensive data collection campaign was initiated to resolve a deficiency in prototype data, within the mouth of the Columbia River (MCR) inlet. Acquisition of prototype data describing the three-dimensional circulation within MCR was intended to improve the hydrodynamic understanding and improve the ability to manage the sediment resources within the inlet. The first-order effects governing the formation of the Columbia River plume occur within the MCR inlet, at an area where relatively few circulation data collection campaigns have been conducted. Data collected will allow the examination of the dynamics associated with the initiation of the Columbia River plume. Information available prior to this data collection could not adequately define whether sand is discharged from the Columbia River estuary to the ocean through the MCR system or vice versa. Time-varying aspects of circulation and sediment flux within the MCR inlet will be examined. Collaboration between the Corps of Engineers, US Geological Survey, and others was required to successfully execute the field data collection campaign. A concurrent multi-beam bathymetric survey of the inlet will allow correlation of bedform features with process measurements. Data collection consisted of detailed measurements for current profile, water level in terms of sub-surface pressure (short- and long-waves), near-bed suspended sediment, and nearbed water conductivity-temperature. Acquisition of vertical profile data for water conductivity-temperature was also made. Data were recorded concurrently at 5 locations spanning a 3-km transect across the MCR, during a deployment period of 2-4 weeks. The deployment occurred during a time when the water column within the MCR is expected to be stratified due to the low flow of the Columbia River flow. Data collection during stratified conditions within the MCR should produce significant insight into dynamics of plume formation, intrusion of dense bottom (marine) water into the MCR from the coast, and secondary flow features associated with baroclinic conditions. The data will be used to describe the lateral and vertical variation in water circulation and sand transport through the MCR for the purpose of verifying conceptual (and computer) models for the flux of water and sand through the MCR. Application of the 3-dimensional baroclinic and process-based sand transport model DELFT3D using the collected data is being presented in a companion paper. (Lesser, Giles). Presently, the MCR inlet is viewed as a system of structural features and transient morphology that interact with the environmental forcing at the inlet to attain a dynamic equilibrium. The imperative is to manage the inlet in terms of the extended time-space scale as defined by natural sediment processes. This paper will present a comprehensive analysis of the physical data collected along the mega-transect and within the estuary and extend the application of the data set to the sediment processes and hydrodynamic understanding of the MCR inlet.
DE: 3022 Marine sediments: processes and transport
DE: 4217 Coastal processes
DE: 4235 Estuarine processes (0442)
DE: 4558 Sediment transport (1862)
DE: 4594 Instruments and techniques
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005