San Francisco Bay Levees

Frequently-anticipated questions:

What does this data set describe?

Title: San Francisco Bay Levees
Abstract:
The bay area levees map depicts the locations of levees around the San Francisco Bay Area. It was created using a combination of the Digital Flood Insurance Rate Maps (DFIRM) data from FEMA and digitized lines from USGS 7.5 minute Topo maps and Google Earth aerial imagery. The data source for each feature is described in the Source attribute field as derived from either FEMA or from the Pacific Institute.
Supplemental_Information:
The DFIRM data is considered preliminary for the purposes of rate zones however the location and quantity of protection sturctures is not expected to be updated before the final publication of the DFIRM dataset.
  1. How should this data set be cited?

    Heberger, Matthew, and Herrera, Pablo, 2009, San Francisco Bay Levees: The Impacts of Sea-Level Rise on the California Coast, Pacific Institute, Oakland CA.

    Online Links:

    This is part of the following larger work.

    Heberger, Matthew, Cooley, Heather, Gleick, Peter, and Herrera, Pablo, 2009, The Impacts of Sea-Level Rise on the California Coast: Pacific Institute, Oakland CA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -123.011689
    East_Bounding_Coordinate: -116.631735
    North_Bounding_Coordinate: 38.827633
    South_Bounding_Coordinate: 32.611509

  3. What does it look like?

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

    Calendar_Date: 2008
    Currentness_Reference: Data reference

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

    Geospatial_Data_Presentation_Form: vector digital data

  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):

      • String (1895)

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

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 10
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -123.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.000000
      Ordinates (y-coordinates) are specified to the nearest 0.000000
      Planar coordinates are specified in meters

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: Attribute values

  7. How does the data set describe geographic features?

    SF_Bay_levees

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    STRUCT_TYP

    WTR_NM

    SOURCE_CIT
    Source of derived data

    Source

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?

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

    Pacific Institute
    c/o Matthew Heberger
    Research Associate/GIS Manager
    654 13th Street
    Oakland, CA 94612
    USA

    (510) 251-1600 (voice)
    (510) 251-2203 (FAX)
    mheberger@pacinst.org

    Hours_of_Service: 9:00 AM to 5:00 PM

Why was the data set created?

Calculate length of structures and extent of protection provided by levees and seawalls.

How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)
    Federal Emergency Managment Agency, Digital Flood Insurance Rate Map (DFIRM): Federal Emergency Management Agency, Washington DC.

    Online Links:

    • www.msc.fema.gov

    Type_of_Source_Media: ESRI shapefile

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

    Date: 1905 (process 1 of 4)
    All final and preliminary DFIRM maps were appended into one document

    Date: 1905 (process 2 of 4)
    In a separate shapefile, all levees shown on USGS 7.5 minute topo maps within 2 kilometers of the coast were digitized over DRG files of the topo maps

    Date: 1905 (process 3 of 4)
    In Google earth a .kmz file was created in which all structures that appeared to protect coastal areas were digitized. Presence of levees was decided based on visual attributes in aerial images of known levees. Where similar attributes were seen elsewhere, and where development appeared to be protected, a levee was drawn.

    Date: 1905 (process 4 of 4)
    All files were appended into one shapefile.

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

    .

    This is part of the following larger work.

    ,.

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

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

    The digitized levee features have not been ground verified, therefore the accuracy cannot be accounted for. For the FEMA data accuracy, see the DFIRM metadata.

  3. How accurate are the heights or depths?

    The digitized levee features have not been ground verified, therefore the accuracy cannot be accounted for. For the FEMA data accuracy, see the DFIRM metadata.

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

    The entire bay area was mapped within 2 kilometers of the coastline for levees included on USGS Topo Maps and all levees are included. The data was not field verified and this is not considered as an official count of all coastal protection features. For the completeness of the FEMA data see the attached metadata.

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

    The dataset is topologically correct.

How can someone get a copy of the data set?

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

Access_Constraints:
None. Data are freely downloadable and available for use in GIS and mapping subject the use constraints below.
Use_Constraints:
The data are freely redistributable with proper metadata and source attribution. Please reference the Pacific Institute as the originator of the dataset in any future products or research derived from these data. This information is being made available for informational purposes only. Users of this information agree by their use to hold blameless the State of California, and its respective officers, employees, agents, contractors, and subcontractors for any liability associated with its use in any form. This work shall not be used to assess actual coastal hazards, insurance requirements, or property values and specifically shall not be used in lieu of Flood Insurance Studies and Flood Insurance Rate Maps issued by the Federal Emergency Management Agency (FEMA).

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

    Pacific Institute
    c/o Matthew Heberger
    Research Associate/GIS Manager
    654 13th Street,
    Preservation Park
    Oakland, CA 94612
    USA

    (510) 251-1600 (voice)
    (510) 251-2203 (FAX)
    mheberger@pacinst.org

    Hours_of_Service: 9:00 AM to 5:00 PM
  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    The data are freely redistributable with proper metadata and source attribution. Please reference the Pacific Institute as the originator of the dataset in any future products or research derived from these data.
    This information is being made available for informational purposes only. Users of this information agree by their use to hold blameless the State of California, and its respective officers, employees, agents, contractors, and subcontractors for any liability associated with its use in any form. This work shall not be used to assess actual coastal hazards, insurance requirements, or property values and specifically shall not be used in lieu of Flood Insurance Studies and Flood Insurance Rate Maps issued by the Federal Emergency Management Agency (FEMA).

  4. How can I download or order the data?

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

    These data are available in Environmental Systems Research Institute (ESRI) shapefile format. The user must have ArcGIS or ArcView 3.0 or greater software to read and process the data file. In lieu of ArcView or ArcGIS, the user may utilize another GIS application package capable of importing the data. A free data viewer, ArcExplorer, capable of displaying the data is available from ESRI at www.esri.com.

Who wrote the metadata?

Dates:
Last modified: 24-Feb-2009
Metadata author:
Pacific Institute
c/o Matthew Heberger
Research Associate/GIS Manager
654 13th Street,
Preservation Park
Oakland, CA 94612
USA

(510) 251-1600 (voice)
(510) 251-2203 (FAX)
mheberger@pacinst.org

Hours_of_Service: 9:00 AM to 5:00 PM
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.9.6 on Thu Feb 26 11:55:11 2009