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Connecticut Erosion Susceptibility

Frequently-asked questions:


What does this data set describe?

Title:
Connecticut Erosion Susceptibility

Abstract:
Connecticut Erosion Susceptibility a 1:24,000-scale, polygon feature-based layer that was developed as a predictive tool to show areas most susceptible to terrace escarpment type erosion. The layer compiled from the soils and quaternary geology data layers and was field tested during October-December, 2005. The Erosion Susceptilibity layer was developed as part of Project #03-02 Statewide GIS Analysis and Mapping of the Geologic Conditions Contributing to Eroding Terrace Escarpments. The layer does not represent eroding conditions at any one particular point in time, but rather base or general conditions which can be accounted for during planning or management strategies. The layer includes 4 types of areas susceptible to erosion, ranked 1 (most susceptible) through 4, and their descriptive attribute. Areas outside of the mapped polygons can be considered less susceptible to erosion.  Data is compiled at 1:24,000 scale. This data is not updated.

Supplemental information:
For additional information, refer to Statewide GIS Analysis and Mapping of the Geologic Conditions Contributing to Eroding Terrace Escarpments, Project #03-02 Final Report, prepared by Mary L. DiGiacomo-Cohen, Long Island Sound Resource Center, University of Connecticut, Avery Point, Groton, CT 06340 in conjunction with North Central Conservation District, 24 Hyde Ave., Vernon, CT, 06066. Report prepared for Nonpoint Source Management Grant Program, Funded under Section 319 (h) of the Federal Clean Water Act, administered by the Connecticut Department of Environmental Protection.

  1. How should this data set be cited?

    State of Connecticut, Department of Environmental Protection (data compiler, editor and publisher), 20051231, Connecticut Erosion Susceptibility: State of Connecticut, Department of Environmental Protection, Hartford, Connecticut, USA.

    Online links:
    Other citation details:
    The State of Connecticut, Department of Environmental Protection is the collector of the data (compiler), the creator and maintainer of the data layer (editor), and producer (publisher) of this information for use. Data compiled at 1:24,000 scale. This layer includes information that is relatively static and does not change over time.

    This is part of the following larger work:

    Mary DiGiacomo-Cohen, 20051231, Statewide GIS Analysis and Mapping of the Geologic Conditions Contributing to Eroding Terrace Escarpments: Long Island Sound Resource Center, Groton, Connecticut, USA.

    Other citation details:
    The erosion_susceptibility data layer is part of a Statewide GIS Analysis and Mapping of the Geologic Conditions Contributing to Eroding Terrace Escarpments, Project #03-02 of the Nonpoint Source Management Grant Program, funded under Section 319 (h) of the Federal Clean Water Act, and administered by the Connecticut Department of Environmental Protection.

  2. What geographic area does the data set cover?

    Bounding coordinates:
    West: -73.742172
    East: -71.781441
    North: 42.052614
    South: 40.989103

  3. What does it look like?

    http://www.cteco.uconn.edu/metadata/dep/browsegraphic/erosionsusceptibilitypolyfullview.gif (GIF)
    Full view of Connecticut Erosion Susceptibility

    http://www.cteco.uconn.edu/metadata/dep/browsegraphic/erosionsusceptibilitypolydetailview.gif (GIF)
    Full view of Connecticut Erosion Susceptibility at 1:24,000 scale.

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

    Calendar date: unknown
    Currentness reference:
    publication date

  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:
      State of Connecticut, United States of America

      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • G-polygon (44036)

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

      The map projection used is Lambert Conformal Conic.

      Projection parameters:
      Lambert Conformal Conic
      Standard parallel: 41.200000
      Standard parallel: 41.866667
      Longitude of central meridian: -72.750000
      Latitude of projection origin: 40.833333
      False easting: 999999.999996
      False northing: 499999.999998

      Planar coordinates are encoded using coordinate pair.
      Abscissae (x-coordinates) are specified to the nearest 0.000250.
      Ordinates (y-coordinates) are specified to the nearest 0.000250.
      Planar coordinates are specified in survey feet.

      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 resolution: 1.000000
      Altitude encoding method: Explicit elevation coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    Connecticut Erosion Susceptibility
    erosion susceptibility represented as polygon features. (Source: State of Connecticut, Department of Environmental Protection)

    OBJECTID
    Internal feature number. (Source: ESRI)
                      

    Sequential unique whole numbers that are automatically generated.

    SHAPE
    Feature geometry. (Source: ESRI)
                      

    Coordinates defining the features.

    EROSION_CA
    erosion category (Source: compiler)
                      

    ValueDefinition
    1
    most susceptible to erosion
    2
    highly susceptible to erosion
    3
    surficial materials susceptible to erosion
    4
    soils susceptible to erosion 

    DESCRIPT
    description of erosion category characteristics (Source: compiler)
                      

    text value

    SHAPE.area
    SHAPE.len
    Entity and attribute overview:
    Includes erosion_category which ranks area features on their susceptibility to erode due to geologic and soils  conditions. Information encoded about these features includes standard cartographic symbology classification schemes. Use the erosion_category to uniquely identify features. Use the AV_LEGEND attribute to symbolize features by type on a map. Use the IMS_LEGEND attribute to more generally symbolize the features by type. 

    Entity and attribute detail citation:
    Stone, J.R., Schafer, J.P., London, E.H. and Thompson, W.B., 1992, Surficial Materials Map of Connecticut, U.S. Geological Survey special map, 2 sheets, scale 1:125,000.
    
    Stone, J.R., Schafer, J.P., London, E.H., DiGiacomo-Cohen, M.L., Lewis, R.S. and Thompson, W.B., 2005, Quaternary Geologic Map of Connecticut and Long Island Sound Basin, U.S. Geological Survey Scientific Investigaions Map 2784, 2 sheets, scale 1:125,000.
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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?

    State of Connecticut, Department of Environmental Protection
    79 Elm Street
    Hartford, Connecticut 06106-5127
    USA

    860-424-3540 (voice)
    860-424-4058 (FAX)
    dep.gisdata@ct.gov
    Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time
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Why was the data set created?

Connecticut Erosion Susceptibility is 1:24,000-scale, polygon feature-based layer that was developed as a predictive tool to show areas most susceptible to terrace escarpment type erosion. This map can be used in conjunction with the 1:24,000 scale Erosion_Sites layer and other documents developed for the Project #03-02: Statewide GIS Analysis and Mapping of the Geologic Conditions Contributing to Eroding Terrace Escarpments.  The objective of this project is to identify the geologic conditions that lead to eroding terrace escarpments throughout the state. This layer is part of an information package that can be used as a planning and management tool by state and municipal officials. Not intended for maps printed at map scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet.)

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How was the data set created?

  1. Where did the data come from?

    soils (source 1 of 6)

    USDA, Natural Resources Conservation Service in cooperation with CT DEP, Natural Resources Center, 1995, soil: Advance Connecticut Soil Survey DatabaseSURGO soils, USDA NRCS & CT DEP/NRC, Hartford, Connecticut, USA.

    Online links:
    Other citation details:
    Soils data mapped at 1 to 12000 scale, compiled at 1 to 15840 scale and digitally encoded at 1 to 15840 scale

    Type of source media: disc
    Source scale denominator: 24000
    Source contribution:
    soils polygons in Shapefile format

    quaternary geology (source 2 of 6)

    Mary L. DiGiacomo-Cohen (comp), 1998, Connecticut Quaternary Geology / Surficial Materials Master (CTQSGEOM): State of Connecticut, Department of Environmental Protection, Hartford, Connecticut, USA.

    Online links:
    This is part of the following larger work:

    Janet Radway Stone, John P. Schafer, Elizabeth Haley London, Mary L. DiGiacomo-Cohen, Ralph S. Lewis, and Woodrow B. Thompson, 1998, Quaternary Geologic Map of Connecticut and Long Island Sound Basin: U.S. Geological Survey, Reston, VA.

    Other citation details:
    Open-File Report 98-371; scale 1:175,000

    Type of source media: disc
    Source scale denominator: 24000
    Source contribution:
    quaternary and surficial materials polygons in shapefile format

    northwest soils (source 3 of 6)

    USDA, Natural Resources Conservation Service and Connecticut DEP, EGIC, 2004, Soils for Northwest Connecticut: USDA NRCS & CT DEP/NRC, Hartford, Connecticut, USA.

    Other citation details:
    ADVANCE INFORMATION SUBJECT TO CHANGE

    Type of source media: disc
    Source scale denominator: 24000
    Source contribution:
    soils polygons for northwestern CT in Shapefile format

    muhelcl (source 4 of 6)

    Natural Resources Conservation Service (NRCS), Unknown, muhelcl: Natural Resources Conservation Service (NRCS), Unknown.

    Other citation details:
    downloaded from Soil Survey Geographic (SSURGO) Database

    Type of source media: disc
    Source scale denominator: 12000
    Source contribution:
    muhelcl table in dbf format

    Erosion_Susceptibility.shp (source 5 of 6)

    State of Connecticut, Department of Environmental Protection (data compiler, editor and publisher), 20051231, Connecticut Erosion Susceptibility: State of Connecticut, Department of Environmental Protection, Hartford, Connecticut, USA.

    Online links:
    Type of source media: disc
    Source scale denominator: 24000
    Source contribution:
    Erosion_Susceptibility.shp is in Shapefile format.

    Erosion_Susceptibility (source 6 of 6)

    State of Connecticut, Department of Environmental Protection (data compiler, editor and publisher), 20051231, Connecticut Erosion Susceptibility: State of Connecticut, Department of Environmental Protection, Hartford, Connecticut, USA.

    Online links:
    Type of source media: disc
    Source scale denominator: 24000
    Source contribution:
    Erosion_Susceptibility is in GeoDatabase Feature Class format.

  2. What changes have been made?

    Date: 2005 (change 1 of 5)
    Soils and northwest soils shapefile data layers were mergered to create a statewide layer. The related table muhelcl was joined to the the merged soils tabel layer based on musym attribute.

    Person responsible for change:
    Mary DiGiacomo-Cohen
    Long Island Sound Resource Center
    UConn Avery Point
    1080 Shennecossett Rd
    Groton, CT 06340
    USA

    860 405-9015 (voice)
    lisrc@uconn.edu

    Data sources used in this process:
    • soils
    • northwest soils
    • muhelcl

    Data sources produced in this process:
    • mergesoils

    Date: 2005 (change 2 of 5)
    The mergesoils and quaternary geology shapefiles were unioned. Attributes for terrace type geology and terrace type soils were added and populated based on soils and geologic characteristics that lead to their susceptibility to erosion. Attribute for draft erosion category (susceptibility) was added and calculated based on terrace soil and terrace geology rankings. Several iterations of 'ranking' took place based on examination of soils and geology relationships, field work, spatial joins with erosion_sites layer, and frequency tables.

    Person responsible for change:
    Mary DiGiacomo-Cohen
    Long Island Souns Resource Center
    UConn Avery Point
    1080 Shennecossett Rd
    Groton, CT 06340
    USA

    860 405-9015 (voice)
    lisrc@uconn.edu

    Data sources used in this process:
    • mergesoils
    • quaternary geology

    Data sources produced in this process:
    • eunion

    Date: 2005 (change 3 of 5)
    Eunion was dissolved on the erosion_category (after final revision). Description attribute was added and populated.

    Person responsible for change:
    Mary DiGiacomo-Cohen
    Long Island Sound Resource Center
    UConn Avery Point
    1080 Shennecossett Rd
    Groton, CT 06340
    USA

    860 405-9015 (voice)
    lisrc@uconn.edu

    Data sources used in this process:
    • eunion

    Data sources produced in this process:
    • Erosion_Susceptibility.shp

    Date: 20061108 (change 4 of 5)
    To improve drawing performance in ArcMap, applied the MultipartToSinglepart command in ArcToolBox to convert the 4 (multi-part) features corresponding to the 4 erosion category values in the original Erosion_Susceptibility.shp shapfile to an output shapefile also named Erosion_Susceptibility.shp with 44,036 single-part features.

    Person responsible for change:
    Howie Sternberg
    State of Connecticut, Department of Environmental Protection
    79 Elm Street
    Hartford, Connecticut 06106
    USA

    860-424-3540 (voice)

    Data sources used in this process:
    • Erosion_Susceptibility.shp

    Data sources produced in this process:
    • Erosion_Susceptibility.shp

    Date: 20061108 (change 5 of 5)
    Convert to GeoDatabase Feature Class format - Defined new Feature Class named Erosion_Susceptibility; and imported the attribute definitions, loaded features and imported metadata from Erosion_Susceptibility.shp shapefile. 
    
    Spatial Reference Properties for Feature Class:
    
    Coordinate System: NAD_1983_StatePlane_Connecticut_FIPS_0600_Feet
    XY Domain MinX: 100000; MaxX: 2247483.645
    XY Domain MinY: 200000; MaxY: 2347483.645
    Precision: 1000

    Person responsible for change:
    Howie Sternberg
    State of Connecticut, Department of Environmental Protection
    79 Elm Street
    Hartford, Connecticut 06106
    USA

    860-424-3540 (voice)

    Data sources used in this process:
    • Erosion_Susceptibility.shp

    Data sources produced in this process:
    • Erosion_Susceptibility

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

  1. How well have the observations been checked?

    The erosion_susceptibility layer retains the feature types and information identified by the State of Connecticut, Department of Environmental Protection and obtained from the compiler. All attributes have valid values. Values are within defined domains. The accuracy test for the attribute values was conducted by comparing the erosion category information presented in the source data with  interactive displays of the data on a computer graphic system.  AV_LEGEND and IMS_LEGEND are broad classifications of erosion_category feature.  AV_LEGEND, and IMS_LEGEND were not manually entered. These additional fields were populated by calculating values equal to existing fields.  The description field was manually selected and populated.

  2. How accurate are the geographic locations?

    The horizontal positional accuracy of this data complies with the United States National Map Accuracy Standards for 1:24,000 scale maps. According to this standard, not more than 10 percent of the locations tested are to be in error by more than 1/50 inch (40 feet) measured on the publication scale of a USGS 7.5 minute topographic quadrangle map. Features are derived from the union of other 1:24,000 scale (Quaternary geology) and 1:12,000 scale (soils) data layers.

  3. How accurate are the heights or depths?

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

    The completeness of the data reflects the chosen feature content of the data sources, which include the soils and quaternary geology data layers. The erosion_susceptibility layer is complete in the sense that it accurately reflects the contents of units chosen by the compiler to represent erodible given the source layers available at the time the State of Connecticut, Department of Environmental Protection created the layer. However, compared to current conditions, the erosion_susceptibility layer is incomplete in that there are minor data gap 'slivers' resulting from merges between the soils data layers for the northwestern portion of the state and the remainder of the state. This data is not updated.

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

    Polygon features conform to the following topological rules. Polygons are single part. There are no duplicate polygons. Polygons do not self overlap. Polygons do not overlap other polygons.
    
    Establishment of logical consistency was performed by the State of Connecticut, Department of Environmental Protection using ESRI ArcGIS software to manually create and control feature topology in SHAPEFILE format. No automated procedures or tests were performed to guarantee desired topology other than visual inspection.
    

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How can someone get a copy of the data set?

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

Access constraints: None. The data is in the public domain and may be redistributed.
Use constraints:
No restrictions or legal prerequisites for using the data. The data is suitable for use at appropriate scale, and is not intended for maps printed at scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet). Although this data set  has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and or related materials.  The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut, Department of Environmental Protection in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data is distributed to the user, modifications made to the data by the user should be noted in the metadata. When printing this data on a map or using it in a software application, analysis, or report, please acknowledge the State of Connecticut, Department of Environmental Protection as the source for this information. For example, include the following data source description when printing this layer on a map: Erosion susceptibility from the Erosion susceptibility layer, compiled and published by CT DEP.  Source map scale is 1:24,000.

Distributor 1 of 1

  1. Who distributes the data set?

    State of Connecticut, Department of Enviromental Protection
    79 Elm Street
    Hartford, Connecticut 06106-5127
    USA

    860-424-3540 (voice)
    860-424-4058 (FAX)
    dep.gisdata@ct.gov
    Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time

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

    Connecticut Erosion Susceptibility

  3. What legal disclaimers am I supposed to read?

    Although this data set  has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and or related materials.  The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut, Department of Environmental Protection in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data is distributed to the user, modifications made to the data by the user should be noted in the metadata.
    

  4. How can I download or order the data?

    • Availability in digital form:


    • Data format:
      in format Shapefile, Feature Class (version ArcGIS)
      Network links:http://www.ct.gov/deep

    • Cost to order the data: An online copy of the data may be accessed without charge.


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

    The data distributor does not provide custom GIS analysis or mapping services. Data is available in a standard format and may be converted to other formats, projections, coordinate systems, or selected for specific geographic regions by the party receiving the data.

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

    Geographic information sytem (GIS), computer-aided drawing or other mapping software is necessary to display, view and access the information.

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Who wrote the metadata?

Dates:
Last modified: 20111208

Metadata author:
Mary DiGiacomo-Cohen
Long Island Sound Resource Center, a partnership between the State of Connecticut, Department of Environmental Protection and the University of Connecticut
Long Island Sound Resource Center, UConn Avery Point, 1080 Shennecossett Rd.
Groton, Connecticut 06340
USA

(860) 405-9015 (voice)
lisrc@uconn.edu

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata(FGDC-STD-001-1998)

Metadata extensions used:
  • http://www.esri.com/metadata/esriprof80.html

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