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Abstract
1. Background
2. Hypotheses
3. Objectives and Methods
4. Measurement Program
5. Major Findings:
5.1. Surfzone Bacterial Contamination Patterns
5.2. Outfall Plume Tracking
5.3. Coastal Transport Processes
6. Transport Processes
7. Conclusions
8. References
9. Acknowledgements
Contacts
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4. Meaurement Program
The measurement program consisted of: 1) a moored array that would collect data to provide a general description and understanding
of coastal circulation and mixing patterns, 2) a complementary hydrographic mapping program that would provide a more detailed description
of the spatial distribution of later column properties, and 3) a surfzone sampling program for bacteria.
Instrumented moorings at 12 locations monitored current velocity, temperature, and salinity at many depths every few minutes for 4 months
in the summer/fall of 2001 ( Figure 1a - 2.41MB PDF file ). This deployment period spans the time period when shoreline bacterial contamination has historically
been at its maximum. Near-bottom wave, water-clarity and suspended sediments were collected at 4 sites to monitor sediment transport processes.
Real-time meteorological data were collected at the shelf break. This array monitored coastal ocean transport processes with temporal frequencies
ranging from a few minutes (e. g. internal waves) to hours and days (e. g. internal tides and wind-driven processes) along 2 cross-shelf transport
pathways and over a nearshore region next to Newport canyon. Additional moorings were deployed in water depths less than 10 m from July to October
2001 to address transport pathways between the nearshore and the surfzone.
The principal moored array was designed by the US Geological Survey (USGS) and prepared and deployed through a cooperative effort among the USGS,
the Naval Postgraduate School (NPS) and Science Applications International Corporation (SAIC). The nearshore set of moorings was deployed by Scripps
Institution of Oceanography (SIO) under contract with OCSD and MBC Applied Environmental Services (MBC) through a contract with the AES power
plant.
A complementary hydrographic mapping program measured the spatial distribution of water column properties including temperature, salinity,
ammonia, bacteria, current velocity and other properties of the water column during six surveys centered around periods of maximum tidal range
(spring tides) ( Figure 1a - 2.41MB PDF file ). These periods were chosen because historical data indicated that most bacterial exceedances at the beach occurred
during spring tides (MEC, 2000). Five of the six surveys overlapped the moored array deployment. A series of CTD casts monitored water properties
along 4 nearshore lines that run parallel to the beach. Simultaneously, a towed undulating vehicle (TUV) monitored water column properties along
10 offshore lines oriented approximately perpendicular to the beach. The hydrographic surveys were designed by OCSD, with advice from the
University of Southern California (USC), and conducted by USC, MEC Analytical Systems, and OCSD.
Samples of three types of fecal indicator bacteria (total coliform, fecal coliform and enterococci) were collected in ankle-depth water
5 days/week, including one weekend day as part of OCSD‰s standard beach monitoring plan. Samples were generally collected between 5 and
10 AM local time, with sampling proceeding from the northernmost station to the southernmost. During the six hydrographic surveys, additional
microbiology samples were collected hourly along the beach for 48 hours at the standard OCSD sampling sites (with the exception of the first
cruise in May when the hourly sampling was done for only 36 hours).
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