A sediment trend analysis (STA(r)) and an acoustic bottom classification (ABC) in eastern Monterey Bay, Moss Landing: Implications to dredge disposal operations

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Frequently-anticipated questions:

What does this data set describe?

Title:
A sediment trend analysis (STA(r)) and an acoustic bottom classification (ABC) in eastern Monterey Bay, Moss Landing: Implications to dredge disposal operations
Abstract: No specific abstract is given in the report or on the CD-ROM
  1. How should this data set be cited?

    McLaren, Patrick, and Consulting, GeoSea, 2000, A sediment trend analysis (STA(r)) and an acoustic bottom classification (ABC) in eastern Monterey Bay, Moss Landing: Implications to dredge disposal operations: GeoSea Consulting, Brentwood Bay, British Columbia.

    Other_Citation_Details:
    Data from CD-ROM held at Moss Landing Harbor, 7881 Sandholdt Road, Moss Landing, California 95039, (831) 633-2461

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -121.87199
    East_Bounding_Coordinate: -121.7752
    North_Bounding_Coordinate: 36.85633
    South_Bounding_Coordinate: 36.74734

  3. What does it look like?

    MLHarbor_2000 (.jpg)
    Sample distribution with bathymetry and coastline for reference

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 1999
    Currentness_Reference: Publication date

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: Digital

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • Point (639)

    2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.00001. Longitudes are given to the nearest 0.00001. Latitude and longitude values are specified in Decimal degrees.

  7. How does the data set describe geographic features?

    Point
    SDTS point (Source: Source report)

    Gravel
    Gravel (Source: GeoSEA Consulting LTD, 2000)

    Range of values
    Minimum:0
    Maximum:40.7
    Units:Percent
    Resolution:0.1

    Sand
    Sand (Source: GeoSEA Consulting LTD, 2000)

    Range of values
    Minimum:0.1
    Maximum:99.9
    Units:Percent
    Resolution:0.1

    Mud
    Mud (Source: GeoSEA Consulting LTD, 2000)

    Range of values
    Minimum:0.1
    Maximum:99.9
    Units:Percent
    Resolution:0.1

    Mean
    Mean grain size (1st moment measure) (Source: GeoSEA Consulting LTD, 2000)

    Range of values
    Minimum:0.045
    Maximum:7.409
    Units:Phi
    Resolution:0.001

    Std. Dev.
    Standard deviation of grain size distribution (sorting; 2nd moment measure) (Source: GeoSEA Consulting LTD, 2000)

    Range of values
    Minimum:0.489
    Maximum:3.533
    Units:Phi
    Resolution:0.001

    Skew.
    Skewness of grain size distribution (3rd moment measure) (Source: GeoSEA Consulting LTD, 2001)

    Range of values
    Minimum:-1.178
    Maximum:2.648
    Units:Phi
    Resolution:0.1

    Folk code
    Classification of sediment on gravel-sand-mud ternary (Source: Folk, Andrews and Lewis, 1970)

    ValueDefinition
    GmSGravelly muddy sand
    GSGravelly sand
    MMud
    MSMuddy sand
    SGSandy gravel
    SMSandy mud

    Phi size classes
    Grain size analysis by phi size classes (Source: GeoSea Consulting, LTD)

    Phi class analyses from -2 phi to 11 phi in 0.5 phi steps.

    Comment
    Comment about presence of hardground (Source: GeoSea Consulting, LTD)

    Those sites that were unsampled due to hardground.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    Patrick McLaren at GeoSea Consulting, LTD for the collection and analysis of the data. For usSEABED: Jane Reid, formatting; Jane Reid and Chris Jenkins, formatting corrections.

  3. To whom should users address questions about the data?

    Moss Landing Harbor District
    7881 Sandholdt Road
    Moss Landing, CA 95039

    (831) 633-2461 (voice)

Why was the data set created?

The specific objectives of this study are: Collect about 600 sediment grab samples from the study area. Analyze all samples for their complete grain-size distributions and input into a Geographic Information System (GIS). Classify and map, using information from the grab sampling program and the acoustic data collected from ABC, bottom types (including the area presently being affected by the ongoing disposal program) from the nearshore to a depth of nearly 300 m, and include this information in the GIS. Undertake STA using proprietary software developed by GeoSea in order to establish the patterns of net sediment transport, areas of erosion, deposition, and dynamic equilibrium. Discuss (i.e., compare and contrast) the results of STA with the present understanding of processes as described in existing work. Use the results of the grain-size analyses, ABC, and STA to: (i) Map sediment transport pathways and their dynamic behavior throughout the study area; (ii) Identify sediment sources and sinks; (iii) Delineate the area potentially impacted by disposal operations; (iii) Propose optimum locations for specific process measurements required to determine transport rates, if desired; (iv) Determine the potential long-term fate of contaminants that may be contained in the sediments. (v) Advise, if applicable, on disposal options to mitigate undesirable affects.

How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: 1999 (process 1 of 1)
    Sediment grab samples were collected from September 3 to 26, 1999, using GeoSea, a 50 foot steel motor-sailor equipped with a hydraulic winch and Shipek grab sampler. This grab sampler enables the top 10 to 15 cm of sediment to be sampled. Many of the harbor samples, including shallow and intertidal samples were collected with a 12-foot, hard-bottom inflatable speedboat (Caribe) equipped with a depth sounder, a small electric winch, and a portable grab sampler. Positioning was achieved on both vessels with a hand held Differential GPS (Garmin GPS75 and Garmin GBR21), providing a typical accuracy of ±5.0 m. In most instances, samples were obtained at predetermined locations ; however, where shoreline structures (docks and marinas) interfered with navigation, a sample was collected as close as practical to the planned position. Representative samples from each successful grab were stored in plastic bags and transported to the GeoSea laboratory in Brentwood Bay, BC, for grain-size analysis. In addition, a second sample was collected out of each grab and refrigerated for later contaminant analysis. Samples were collected on a regular, hexagonal grid with a spacing of 200 m over the canyon (Area A). The remaining area (Area B) was sampled at a spacing of 500 m. A total of 639 sample sites were visited, of which 6 were unsuccessful. Failures were in water depths of greater 250 m and it is believed that sampling difficulties (i.e., currents and dragging the grab) increased with increasing depth. The failure to obtain the sample in these conditions was not the result of a rocky bottom, despite several drops of the sampler. All samples were analyzed for their complete grain-size distribution using a Malvern 2600L laser particle sizer. Prior to every analysis, the laser beam is aligned and a background measurement of the suspension medium is taken. Samples are initially well mixed before obtaining a representative sub-sample for analysis. The amount of sediment required is about 2 to 4 grams for sands and 0.5 to 1 gram for silt and clay. Samples are introduced into the water-bath of the Malvern by wet sieving through a 1mm mesh, eliminating possible blockage of the pumping mechanism by particles that are too large. If material remains on the 1mm sieve then the weight percent for each of the coarse sizes (-2.0 phi to 0.5 phi; 4.0mm to 0.7mm) is obtained by dry sieving at 0.5 phi intervals. Disaggregation of the sample is achieved by both mechanical stirring and mild ultrasonic dispersion in the water-bath. Two separate sub-samples are analyzed and the results averaged. Samples are usually analyzed using two lenses; the 100mm lens (range 0.19mm to 0.5 microns; 2.5 phi to 11 phi) and the 1000mm lens (range 1.88mm to 5 microns; -0.91 phi to 7.6 phi). Sieving is carried out at half-phi intervals from -2.0 phi to 0.5 phi. The weights are normalized and the percentage smaller than 0.5 phi is used to renormalize the Malvern values using the methods described above. The portion of the lens data above 0.5 phi is removed and replaced with sieve data.

    Person who carried out this activity:

    GeoSea Consulting, LTD
    789 Saunders Lane
    Brentwood Bay, BC V8M 1C5

    250-652-1334 (voice)
    www.geosea.ca

    Data sources used in this process:
    • Method described in appendix III of the report (CD-ROM).

    Data sources produced in this process:

    • MLHarbor_2000

  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    No estimation for grainsize accuracy is given in the original report. For usSEABED, digital location data were converted from UTM X-Y coordinates into decimal degrees. For numeric data, where appropriate, data were tested for completeness using MS Excel. Locations checked using GIS.

  2. How accurate are the geographic locations?

    Navigation by differential GPS, with typical accuracy of +/- 5 meters.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    All data is included in usSEABED, including hard bottom and kelp.

  5. How consistent are the relationships among the observations, including topology?

    Data fall within normal ranges for data types given.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: Data held on CD-ROM at Moss Landing Harbor District offices.
Use_Constraints: None

  1. Who distributes the data set? (Distributor 1 of 1)

    Moss Landing Harbor District
    7881 Sandholdt Road
    Moss Landing, CA 95039

    (831) 633-2461 (voice)

  2. What's the catalog number I need to order this data set?

    GeoSea 2000 report

  3. What legal disclaimers am I supposed to read?

    Although this dataset has been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data. Users of the data should be aware of the limitations of the data due to possible imprecision due to navigational inaccuracies, sampling and analytical techniques, and statistical limitations.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    CD-ROM reader; MS Excel

Who wrote the metadata?

Dates:
Last modified: 2005
Metadata author:
U.S. Geological Survey
c/o Jane A. Reid
Geologist
400 Natural Bridges Drive
Santa Cruz, CA 95060

831-427-4727 (voice)
jareid@usgs.gov

Contact_Instructions: Email preferred
Metadata standard:
CSDGM Version 2 (FGDC-STD-001-1998)

Generated by mp version 2.8.17 on Sat May 20 22:08:14 2006