Connecticut Erosion Sites is a site specific, point feature-based layer developed at 1:24,000-scale that includes decriptive information regarding the character of the erosion (severity, slope, geologic factors) at selected locations through out the state. The layer is based on information collected and compiled during October-December, 2005 while field testing the applicability of the Erosion Susceptilibity layer developed as part of Project #03-02 Statewide GIS Analysis and Mapping of the Geologic Conditions Contributing to Eroding Terrace Escarpments. The layer represents conditions at a particular point in time. The layer includes 83 locations and descriptive attributes (site name, severity of erosion, description, etc) as well as attributes from a spatial join with merged soils and quaternary geology layers. Features are point locations that represent the selected study areas within the state; it is NOT a comprehensive inventory of erosion locations. Data is compiled at 1:24,000 scale. This data is not updated.
Connecticut Erosion Sites is a site specific data layer developed at 1:24,000-scale. The purpose of this layer is show locations and provide desriptions of erosion sites used to confirm the applicability of the draft erosion suscepibility map. Erosion sites were inventoried in selected areas of the state wide study area. This map should be used in conjunction with the final 1:24,000 scale Erosion Susceptibility 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 tools 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_severity from the Erosion_sites layer, compiled and published by CT DEP. Source map scale is 1:24,000.
79 Elm Street
The erosionsites layer retains the feature types and information identified by the State of Connecticut, Department of Environmental Protection and obtained from the data compiler. All attributes have valid values. Values are within defined domains. The accuracy test for the attribute values was conducted by comparing the information presented in the source data with 1:24,000-scale field sheets and interactive displays of the data on a computer graphic system. These check plot maps and computer displays depicted and labeled the erosionsites features in different colors based on values for comparison with the original data source. AV_LEGEND and IMS_LEGEND are broad classifications of erosionsites features. AV_LEGEND, and IMS_LEGEND were not manually entered. These additional fields were populated by calculating values equal to existing fields. Erosionsites features were manually selected and populated with descriptive attributes values to (uniquely) identify and describe individual features. Attributes respresenting geologic and soils conditions for each sites, and erosion category were populated by spatial join.
Point features conform to the following topological rules. Points are single part. There are no duplicate points. Points do not overlap. 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 feature content of the data sources, which include the FIELD DATA SHEETS for the project. The erosionsites layer is complete in the sense that it accurately reflects the contents of the Erosion sites field information available at the time the State of Connecticut, Department of Environmental Protection created the layer. However, compared to current conditions, the erosionsites layer is incomplete. 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. Some feature locations were interpolated from the transporation features, surface water features, elevation contours, buildings, and built-up areas depicted on USGS 7.5 minute topographic quadrangle maps. Other feature locations were derived from GPS coordinates; their horizontal precision exceeds the map standard.Typically, the Trimble Pro XR collects data with the PDOP set to 6.0 and the S/N set to 10.0 the standard error of the collected data is less than 1 meter, so the 95% confidence is on the order of 2 meters. Point features represent approximate positions for linear or large area objects or observations that are transient, variable or temporal in nature. Some features are accurately positioned because GPS-based coordinates were collected at the actual location of the site in the field, and other features are less accurately positioned because the site represents a large area which was interpolated from topographic quadrangle maps.
field sheets consist of draft erosion susceptibility map overprinted on DRG topographic quads at 1:24,000 scale
GPS.shp is in Shapefile format.
union of soils and quaternary geology data layers
Erosion_Susceptibility_Sites.shp is in Shapefile format.
Erosion_Susceptibility_Sites is in GeoDatabase Feature Class format.
Feature digitizing and attribution (heads up digitizing method) - Using ESRI ArcView 3 software, features appearing on the source map were manually digitized on the screen (heads-up digitizing) at display scales greater than 1:24,000 using USGS 7.5 minute topographic quadrangle maps displayed in the background for reference. Individual features were digitized based on topographic base information. Features were assigned attribute values based on information shown on the field maps. Feature location and attribute accuracy was visually checked and inspected by symbolizing and labeling features according to attribute value on the computer screen and comparing this information to the orginal source data.
UConn Avery Point
1080 Shennecossett Rd
Erosion locations were captured with a Trimble Pro XR backpack GPS unit. The unit's filters were set to capture points with a PDOP of < 10.0 and a S/N (signal to noise ration) of greater > 1.0. The data was post processed against a base station and then exported into ArcView shape files using the Connecticut State Plane NAD 83 coordinate system. Features were copied to erosionsites.shp and assigned attribute values based on information shown on the field maps and field logs. Feature location and attribute accuracy was visually checked and inspected by symbolizing and labeling features according to attribute value on the computer screen and comparing this information to the orginal source data.
79 Elm St
Attribute enhancements - a spatial join was used to add attributes from a data layer respresenting the union of soils and quaternary geology (which was dissolved to create Erosion Susceptibilty layer). Additionally the AV_LEGEND attribute was added to establish a very general classification scheme for symbolizing features.
UConn Avery Point
1080 Shennecossett Rd
Convert to GeoDatabase Feature Class format - Defined new Feature Class named Erosion_Susceptibility_Sites; and imported the attribute definitions, loaded features and imported metadata from Erosion_Susceptibility_Sites.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
79 Elm Street
Internal feature number.
ESRI
Feature geometry.
ESRI
Site identifier or casual name
compiler
Erosion severity
compiler
brief decription of site conditions, geologic observations
compiler
Town Name
compiler
date of site visit YYYYMMDD
compiler
source of location data
compiler
digitized point location based on topographic base map features
compiler
point location from Trimble Pro XR unit/software
compiler
file name of first photo of this site
compiler
file name of second photo of this site
compiler
file name of third photo of this site
compiler
file name of fourth photo of this site
compiler
same as severity of erosion
compiler
Quaternary Geologic polygon code
Quaternary Geologic Map of Connecticut and Long Island Sound Basin
Quaternary Geology
Quaternary Geologic Map of Connecticut and Long Island Sound Basin
Depositional System Code
Quaternary Geologic Map of Connecticut and Long Island Sound Basin
Depositional System
Quaternary Geologic Map of Connecticut and Long Island Sound Basin
Surficial Materials Code
Quaternary Geologic Map of Connecticut and Long Island Sound Basin
Surficial Materials
Quaternary Geologic Map of Connecticut and Long Island Sound Basin
The symbol used to identify the soil map unit
Natural Resources Conservation Service (NRCS)
Correlated name of the map unit (field name for surveys in progress)
Natural Resources Conservation Service (NRCS)
The overall Highly Erodible Lands (HEL) classification for the mapunit based on the rating of its components for wind and water HEL classification
Natural Resources Conservation Service (NRCS)
x coordinate
ESRI
y coordinate
ESRI
Erosion category
compiler
Highly erodible soil and coarse grained erodible surficial materials
compiler
Highly erodible soil and finer grained erodible surficial materials
compiler
Erodible surficial materials
compiler
Highly erodible soil
compiler
Includes Erosion sites features such as general descriptions, geologic and soils conditions at selected erosion locations. Information encoded about these features includes x and y coordinates and standard cartographic symbology classification schemes. Use the AV_LEGEND attribute to symbolize features by type on a map. Use the comment to label features on a map. Additional related attribute data tables are not included with the distributed layer, but are available upon request.
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.
79 Elm Street
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.