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.
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.)
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.
publication date
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.
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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.
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.
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.
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.
soils polygons in Shapefile format
quaternary and surficial materials polygons in shapefile format
soils polygons for northwestern CT in Shapefile format
muhelcl table in dbf format
Erosion_Susceptibility.shp is in Shapefile format.
Erosion_Susceptibility is in GeoDatabase Feature Class format.
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.
UConn Avery Point
1080 Shennecossett Rd
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.
UConn Avery Point
1080 Shennecossett Rd
Eunion was dissolved on the erosion_category (after final revision). Description attribute was added and populated.
UConn Avery Point
1080 Shennecossett Rd
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.
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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
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Internal feature number.
ESRI
Feature geometry.
ESRI
erosion category
compiler
most susceptible to erosion
Highly erodible soil and coarse grained erodible surficial materials
highly susceptible to erosion
Highly erodible soil and finer grained erodible surficial materials
surficial materials susceptible to erosion
Erodible surficial materials
soils susceptible to erosion
Highly erodible soil
description of erosion category characteristics
compiler
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.
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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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.
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.
Long Island Sound Resource Center, UConn Avery Point, 1080 Shennecossett Rd.