Digital Overlay for Soils of Lafourche Parish, Louisiana.

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Frequently-anticipated questions:


What does this data set describe?

    Title: Digital Overlay for Soils of Lafourche Parish, Louisiana.
    Abstract:
    This data set contains vector line map information. The vector data contain selected base categories of geographic features, and characteristics of these features, in digital form. The information was collected by digitizing and/or scanning soil information complied onto 7.5-minute quadrangle mylar sheets, creating an editable, digital soil coverage. The data set used 1:24000 scale hardcopy USGS standard quadrangle maps and the State Soil Survey of Lafourche Parish as a data development resource. The classified data was derived from actual field identification and sampling performed by the Natural Resource Conservation Service (NRCS), in Alexandria, Louisiana (formerly Soil Conservation Service). Digital data is available by parish. The digital data is not Soil Survey Geographic database (SSURGO) certified.

  1. How should this data set be cited?

    United States Geological Survey, and Natural Resource Conservation S, 20020313, Digital Overlay for Soils of Lafourche Parish, Louisiana.: US Geological Survey, National Wetlands Research Center, Lafayette, Louisiana, US.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -91.007
    East_Bounding_Coordinate: -88.792
    North_Bounding_Coordinate: 30.125
    South_Bounding_Coordinate: 28.994

  3. What does it look like?

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

    Beginning_Date: 01-Oct-1997
    Ending_Date: 12-Mar-2002
    Currentness_Reference: Publication date of sources

  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?

      Indirect_Spatial_Reference: The State of Louisiana
      This is a Vector data set.

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

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 15
      Transverse_Mercator:
      Longitude_of_Central_Meridian: -93
      Latitude_of_Projection_Origin: 0
      False_Easting: 500,000
      False_Northing: 0
      Scale_Factor_at_Central_Meridian: .9996

      Planar coordinates are encoded using Coordinate Pair
      Abscissae (x-coordinates) are specified to the nearest .61
      Ordinates (y-coordinates) are specified to the nearest .61
      Planar coordinates are specified in Meters

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is GRS 1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257.

  7. How does the data set describe geographic features?

    Soils
    A natural, three-dimensional body at the earth's surface. It is capable of supporting plants and has properties resulting from the integrated effect of climate and living matter acting on earthy parent material, as conditioned by relief over periods of time. (Source: USDA, NRCS, and Soil Survey of Lafourche Parish.)

    soil_code
    Codes for soil units (Source: Soil Survey for Lafourche Parish, Louisiana: NRCS, in cooperation with Louisiana Agricultural Experiment Station and Louisiana Soil and Water Conservation Committee. Alexandria, Louisiana, USDA.)

    ValueDefinition
    AEAllemands Muck
    ANAllemands-Larose Association
    AmAllemands Muck, Drained
    ATBAquents, Dredged, 1 to 5 Percent Slopes, Occasionally Flooded
    BBBarbary-Fausse Association
    BEBellpass-Scatlake Association
    CeACancienne Silty Clay Loam, 0 to 1 Percents Slopes, Occasionally Flooded
    CfACancienne Silt Loam, 0 to 1 Percents Slopes, Occasionally Flooded
    CmCancienne (Commerce) Silt Loam
    CoCancienne (Commerce) Silt Clay Loam
    FAFausse-Sharkey Association
    FEFelicity Loamy Fine Sand, Frequently Flooded
    KEKenner Muck
    LALafitte-Clovelly Association
    RaRita Muck
    RvRita Variant Muck
    SAScatlake Muck
    SCScatlake-Felicity Association
    ShSchriever (Sharkey) Silty Clay Loam
    SIASchriever Clay, 0 to 1 Percent Slopes, Frequently Flooded
    SkSchriever (Sharkey) Clay
    SrSchriever (Sharkey) Clay, Occasionally Flooded
    TbASchriever-Cancienne Silty Clay Loams, 0 to 1 Percent Slopes
    TBTimbalier-Bellpass Association
    TnThibaut (Tunica) Clay, Frequently Flooded
    TuThibaut (Tunica) Clay
    VaVacherie Silt Loam
    UBUrban Land
    waterwater

    Entity_and_Attribute_Overview:
    The data set consists of vectored data for the 39 quadrangles in Lafourche Parish. Each polygon in the coverage has been assigned a corresponding soil code. The Parish's quadrangles can be found in the "Louisiana Index to topographic and other Map Coverage", published and distributed by the USGS, National Mapping Program. The description of soil codes can be found in the Soil Survey of Lafourche Parish.
    Entity_and_Attribute_Detail_Citation:
    Soil Survey of Lafourche Parish, published by the USDA, NRCS, and the Louisiana Index to topographic and other Map Coverage, Published and distributed by the USGS, National Mapping Program.


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?

    The U.S. Geological Survey, National Wetlands Research Center acknowledges the NRCS for use of data derived from the SSURGO soils maps for Lafourche Parish, Louisiana.

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

    U.S. Geological Survey, National Wetlands Research Center
    c/o Steve Hartley
    Senior Geographer/GIS Analyst
    700 Cajundome Boulevard
    Lafayette, Louisiana 70506
    USA

    337-266-8543 (voice)
    337-266-8616 (FAX)
    steve_hartley@usgs.gov

    Hours_of_Service: 8:00 am to 4:00 pm CST Monday through Friday


Why was the data set created?

To provide digital overlays of the soils of Louisiana by parish for the NRCS, that can be updated and used as a layer in a GIS application.


How was the data set created?

  1. From what previous works were the data drawn?

    USDA Map (source 1 of 3)
    United States Department of Agr, in cooperation with the Louisiana , Unknown, Soil delineated aerial photography: USDA, NRCS, Alexandria, Louisiana.

    Type_of_Source_Media: Stable-based Material
    Source_Scale_Denominator: 24000
    Source_Contribution: Spatial and Attribute information for soil units.

    USDA, NRCS (source 2 of 3)
    USDA, NRCS, in cooperation with Louisiana A, 19800101, Soil Survey of Lafourche Parish, Louisiana: USDA, NRCS, Alexandria, Louisiana.

    Type_of_Source_Media: Paper
    Source_Scale_Denominator: 20000
    Source_Contribution: Secondary attribute information for soil units.

    DOQQ (source 3 of 3)
    National Digital Orthophoto Program (NDOP), 19981125, 1993 Landsat TM Imagery: USDA, NRCS, National Cartography and Geospatial Center., Fort Worth, TX.

    Type_of_Source_Media: Digital Imagery
    Source_Contribution: Data for land cover/land use classification

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

    Date: 1998 (process 1 of 1)
    The following is a generalized description of the processes used in creating the parish soil digital coverages for Louisiana. Data for some parish soil maps may vary slightly. The data set was compiled by taking the original soil lines drawn over aerial photography by NRCS and transferring them to 7.5 minute quadrangle mylar sheets with a scale of 1:24,000 aided by the most accurate and available imagery. Soil lines for Lafourche Parish were initially compiled by the NRCS, however the processes that follow were all performed at the NWRC. The compiled soil lines for each quadrangle were then digitized and/or scanned individually. All quadrangles were then appended, cleaned, joined together and labeled to form the body of the parish coverage. On-screen land-water interfaces for every quadrangle were constructed, utilizing digital orthophoto quarter quadrangles (DOQQ's) after the soil lines were digital. On-screen and tablet digitizing was done using Production ARC/Edit, an adaptation of ESRI's ARC/Edit module. Scanning was performed on the IDEAL, FSC 8010 Color Scanner utilizing CADImage_Scan+Feature version 1.0 software and I_Vector version 3.81 for vectorization. The ARC/Edit module was used for coverage generation with geospatial data, building, cleaning, and joining coverages. Polygons were assigned attributes, as labels, in ArcView. The information is stored both as an ARCInfo coverage and exported .e00 compression file.

  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?

    The accuracy is not based on a formal quantitative assessment and was based on the judgement of the soil conservationist in the field. Ground truthing was not performed for this project. To attain a better estimate of accuracy, a formal re-evaluation of the soils of Lafourche Parish, Louisiana would be necessary to see if there are areas where discrepancies exist.

  2. How accurate are the geographic locations?

    Not applicable

  3. How accurate are the heights or depths?

    Not applicable

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

    All data sets were derived in the same general format. All soil information was transferred onto transparent mylar sheets, for each topographic quadrangle in the parish, from the existing State Soils Survey for the parish. Mylar overlays were digitized (entered at an error of less than .005 for geographic positioning) and/or scanned then rectified. Each quadrangle mylar overlay was digitized and/or scanned separately and therefore may represent different amounts of human and/or equipment error. Parish coverage quadrangles land-water interfaces were corrected by best judgement on-screen digitizing to Digital Orthophoto Quarter Quadrangles (DOQQ's), if available. For parishes created before DOQQ's were available, the land-water interfaces were included on the mylar sheets. For parishes created after DOQQ's became available, the land-water interfaces were digitized on-screen separately from the soil lines; therefore they are not included on the mylar sheets. The land-water coverages and soil line coverages were then appended and cleaned to create the total quadrangle coverage. Each quadrangle was edited individually, and then all quadrangles in the parish were joined together. Once joined together, editing was done along all quadrangle boundaries to match lines and labels. When line or label errors were found, all corrections were made upon approval of the NRCS. Problems with labeling occurred along adjoining parish boundaries, due to different labeling conventions in each parish. A standard labeling convention system for the whole state of Louisiana must be created to remedy the problem. Until this standard is developed, the following labeling tactics have been used. New labels were created for parish coverages in order to match labels for adjoining parishes. Changes were dependent upon soil definition, polygon size, and cases of duplication problems. A duplication problem means the label already existed in the parish coverage and is a different unit altogether and therefore can not be added to that legend. New labels were also created when new lines were needed to reduce confusion. Lines were added in special cases: 1) if it was advantageous to extend an unit a small portion into the next parish, rather than renaming the whole polygon; and 2) if the two units adjoining are similar, differing only in transitional phase, then a line was added at the most logical area of transition, aided by imagery, in order to keep the two units separate. New labels were created in the coverages which the line was added as long as there was not duplication problems. If major complications occurred when trying to add labels, these areas were left as is, waiting for a standard soil convention. These problems can be fixed after a standard Louisiana State soil code convention is established. The attribute legend for Lafourche Parish is found in the Entity and Attribute Section. This includes current modifications for completeness with surrounding parishes. All changes to the Lafourche Parish soils lines and legend are documented in a report to be stored with the state soils archives at the NRCS in Alexandria, LA. Modifications to the Lafourche Parish legend include the following: Added Tu, from Assumption, replacing "touching" Sk polygons; Added ATB, CeA, CfA, SIA, TbA, and UB, from Terrebonne, to match and correct boarder inconsistencies; A few soil code names have changed to soils that lie below the Louisiana thermal line, changes in Lafourche include; Commerce to Cancienne, Sharkey to Schriever, and Tunica to Thibaut.

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

    All polygons are closed, and have been cleaned in an editing environment. Adjacent polygons do not have identical attributes. Each polygon has one and only one attribute.


How can someone get a copy of the data set?

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

Access_Constraints:
It is strongly recommended that this data is directly acquired from the distributor described above or from another USGS Biological Resources Division server and not indirectly through other sources which may have changed the data in some way. The distributor makes no claims as to the data's suitability for other purposes.
Use_Constraints:
Acknowledgement of the U.S. Geological Survey, National Wetlands Research Center as a data source would be appreciated in products developed from these data, and such acknowledgment as is standard for citation and legal practices for data source is expected by users of this data. Sharing new data layers developed directly from these data would also be appreciated by U.S. Geological Survey, National Wetlands Research Center staff. Users should be aware that comparison with other data sets for the same area from other time periods may be inaccurate due to inconsistencies resulting from changes in mapping conventions, data collection, and computer processes over time. These data are not legal documents and are not to be used as such. This data is not STATSGO or SSURGO certified.

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

    U.S. Geological Survey, National Wetlands Research Center
    c/o Steve Hartley
    Senior Geographer/GIS Analyst
    700 Cajundome Blvd.
    Lafayette, Louisiana 70506
    USA

    337-266-8543 (voice)
    337-266-8616 (FAX)
    steve_hartley@usgs.gov

    Hours_of_Service: 8:00 am to 4:00 pm CST Monday through Friday
  2. What's the catalog number I need to order this data set?

    NRCS Soil Maps for Lafourche Parish

  3. What legal disclaimers am I supposed to read?

    Although these data have been processed successfully on a computer system at the U.S. Geological Survey, National Wetlands Research Center, no warranty expressed or implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. This disclaimer applies both to individual use of the data and aggregate use with other data. It is strongly recommended that these data are directly acquired from a Biological Resources Division server, and not indirectly through other sources which may have changed the data in some way. It is also strongly recommended that careful attention be paid to the contents of the metadata file associated with these data. U.S. Geological Survey, National Wetlands Research Center shall not be held liable for improper or incorrect use of the data described and/or contained herein. So, these data are provided "as is" and without any express or implied warranties, including, without limitation, the implied warranties or merchantability and fitness for a particular purpose. Also, use of trade names or commercial products in this metadata is solely for the purpose of providing specific information, and does not imply recommendation or endorsement by the US Government. Any downloading and use of these data signifies a user's agreement to comprehension and compliance of the U.S. Geological Survey, National Wetlands Research Center Standard Disclaimer. Insure all portions of metadata are read and clearly understood before using these data in order to protect both user and U.S. Geological Survey, National Wetlands Research Center interests.

  4. How can I download or order the data?

  5. Is there some other way to get the data?

    Not available


Who wrote the metadata?

Dates:
Last modified: 13-Mar-2002
Last Reviewed: 18-Mar-2002

Metadata author:
Joan C. Kester
U.S. Geological Survey, National Wetlands Research Center
Geographer
700 Cajundome Blvd
Lafayette, LA 70506
USA

337-266-8611 (voice)
337-266-8616 (FAX)
joan_kester@usgs.gov

Hours_of_Service: 8:00 am to 4:00 pm CST Monday through Friday
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


Generated by mp version 2.7.33 on Mon Jul 07 08:08:54 2003