A sediment trend analysis (STA) of Santa Cruz Harbor and its vicinity: Implications to dredge disposal operations

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Frequently-anticipated questions:

What does this data set describe?

A sediment trend analysis (STA) of Santa Cruz Harbor and its vicinity: 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, 2001, A sediment trend analysis (STA) of Santa Cruz Harbor and its vicinity: Implications to dredge disposal operations: Sea Technology March 2001, pp. 10-14, Compass Publications, Arlington, VA.

    Data from CD-ROM held at Santa Cruz Port District, 135 Fifth Avenue, Santa Cruz, CA 95062, (831) 475-6161 (831) 475-9558 FAX

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -122.09697
    East_Bounding_Coordinate: -121.88691
    North_Bounding_Coordinate: 36.97825
    South_Bounding_Coordinate: 36.89583

  3. What does it look like?

    SCHarbor_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 (829)

    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 .00001. Longitudes are given to the nearest .00001. Latitude and longitude values are specified in Decimal degrees.

  7. How does the data set describe geographic features?

    SDTS point (Source: Source report)

    Gravel (Source: GeoSEA Consulting LTD, 2001)

    Range of values

    Sand (Source: GeoSEA Consulting LTD, 2001)

    Range of values

    Mud (Source: GeoSEA Consulting LTD, 2001)

    Range of values

    Mean grain size (1st moment measure) (Source: GeoSEA Consulting LTD, 2001)

    Range of values

    Std. Dev.
    Standard deviation of grain size distribution (sorting; 2nd moment measure) (Source: GeoSEA Consulting LTD, 2001)

    Range of values

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

    Range of values

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

    GmSGravelly muddy sand
    GSGravelly sand
    MSMuddy sand
    SGSandy gravel
    SMSandy mud

    Phi size classes
    Grainsize by phi-size classes (Source: GeoSea Consulting, LTD)

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

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

    Those sites that were unsampled due to hardground or kelp.

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 Geo Sea Consulting 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?

    Santa Cruz Port District
    c/o Brian Foss
    135 Fifth Street
    Santa Cruz, CA 95062

    (831) 475-6161 (voice)
    (831) 475-9558 (FAX)

Why was the data set created?

The specific objectives of this study are: (1) Collect about 800 sediment grab samples from the seabed of Santa Cruz Harbor and its surrounding waters. (2) Analyze each of the samples for its complete grain-size distribution and 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 for all sediment types (mud and sand) contained within study area. (3) Discuss the results of STA with the present understanding of processes as described in existing work. (4) Use the above findings to: (i) Predict the fate of dredged material disposed of in the littoral zone for both the sand and mud constituents that may be present; (ii) Delineate the potential areas impacted by disposal operations; (iii) 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 28 to October 14, 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. Samples were collected on a regular, hexagonal grid with a spacing of 250 m in the vicinity of the harbor.. The remaining area was sampled at a spacing of 500 m. A total of 829 sample sites were visited, of which 88 were found to be "hard ground" (i.e., cobbles or bigger, or scoured bottom) and no sample could be taken. . In 29 of the 88 hard ground sample sites, the presence of kelp precluded taking a sample. A site was designated as hard ground after several separate drops of the grab sampler failed to retrieve sediment. 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 to 0.51; 4.0mm to 0.7mm) is obtained by dry sieving at 0.5 intervals. Disaggregation of the sample is achieved by both mechanical stirring and mild ultrasonic dispersion in the water-bath2. Two separate sub-samples are analyzed and the results averaged. 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 renormalise 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)

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

    Data sources produced in this process:

    • SCHarbor_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 Santa Cruz Port District
Use_Constraints: None

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

    Santa Cruz Port District
    135 Fifth Avenue
    Santa Cruz, CA 95062

    (831) 475-6161 (voice)
    (831) 475-9558 (FAX)

  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 and MS Excel

Who wrote the metadata?

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

831-427-4727 (voice)

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

Generated by mp version 2.8.17 on Sat May 20 21:36:58 2006