NWI digital data files are records of wetlands location and classification as defined by the U.S. Fish & Wildlife Service. This dataset is one of a series available in 7.5 minute by 7.5 minute blocks containing ground planimetric coordinates of wetlands point, line, and area features and wetlands attributes. When completed, the series will provide coverage for all of the contiguous United States, Hawaii, Alaska, and U.S. protectorates in the Pacific and Caribbean. The digital data as well as the hardcopy maps that were used as the source for the digital data are produced and distributed by the U.S. Fish & Wildlife Service's National Wetlands Inventory project. Base map dates Range from Oct. 1981 to present. CGIA has compiled the 7.5 minute quadrangle extent digital files into river basin map extent files. These extents are stored as tiles in a GIS library. The NWI identifier is in in the condensed format in the polygon (area) attributes, and in a parsed format in the arc (line) attributes. Other wetland classification exist for North Carolina.
The data provide consultants, planners, and resource managers with information on wetland location and type. The data were collected to meet U.S. Fish & Wildlife Service's mandate to map the wetland and deepwater habitats of the United States.
24,000-scale NWI files were joined to create 1:100,000-scale tiles which were then joined to created river basin tiles. The tile names, abbreviations and approximate file sizes are list here. >River Basin ABBREV MB >Broad brd 2 >Cape Fear cpf 60 >Catawba ctb 8 >Chowan cho 8 >French Broad frb 2 >Hiwassee hiw 1 >Little Tennessee ltn 1 >Lumber lbr 24 >Neuse neu 39 >New new 2 >Pasquotank pas 13 >Roanoke roa 19 >Savannah sav no digital data >Tar-Pamlico tar 31 >Watauga wat 1 >White Oak wok 10 >Yadkin yad 19 >Revisions and updates to this layer include: >system filename: /library/librb/tiles/(rivbasabbrev)/nwi >filesizes range from 1 - 60 mb per tile >4.) directory: nwi_599 filenames: (rivbas)nwi599 >The May 1999 updates to this layer consisted of combining the >100k tiles into river basin files and stripping out the quadrangle >neatlines. During this update the data was also projected from NAD27 >datum, State Plane projection, units of measure feet TO: NAD83 DATUM, >State Plane PROJECTION, UNITS OF MEASURE METERS. This was done to >comply with the NC Geographic Information Coordinating Council's >"Statement of Direction for North Carolina Corporate Geographic Database >Horizontal Reference, Datum and Unit of Measure". This reprojecting >was done in various ways depending on the data type and content. >Vector data was projected using the 'project' command in ESRI's Arc >software and topology was cleaned and built based on coverage needs. >Raster data was projected using ESRI's Grid module and various steps >as applicable. >3.) directory: nwi_1097 filenames: nwi(100kabbr)1097 >In October 1997, additional 24k tiles were being combined into 100k >tiles. If the 24 k source changed at any time, these updates >were also added to the 100k. The following tiles were edited or >added: Asheville, Gastonia, Lancaster. >2.) directory: nwi_1995 filenames: nwi(100kabbr)(month)95 >In 1995, additional 24k tiles were being combined into 100k >tiles. If the 24 k source changed at any time, these updates >were also added to the 100k. >During the year, 29 tiles were created or updated as follows: >October 1995 - Bayboro >September 1995 - Norfolk, Plymouth, Whiteville >August 1995 - Raleigh, Roanoke Rapids >July 1995 - Asheville, Charlotte, Florence, Fontana Lake, >Gaston, Hendersonville, Johnson City, Knoxville, Laurinburg >June 1995 - Morehead City >May 1995 - Boone, Cleveland, Kinston, Salisbury >April 1995 - Fayetteville, Henderson >March 1995 - Chapel Hill, Greensboro >February 1995 - Rocky Mount >January 1995 - Danville, Galax, Southern Pines, Wytheville >1.) directory: nwi_1994 filenames: nwi(100kabbr)(month)94 >In 1994, the 24k tiles were being combined into 100k tiles. >If the 24 k source changed at any time, these updates were >also added to the 100k. >During the year, 14 tiles were created as follows: >November 1994 - Winston-Salem, New River, Manteo, Hickory >October 1994 - South Boston >September 1994 - Wilmington, Myrtle Beach, Elizabethtown >August 1994 - Virginia Beach, Cape Fear >June 1994 - Emporia, Elizabeth City, Currituck Sound >May 1994 - Cape Hatteras
source photography dates
Federal, State, and local regulatory agencies with jurisdiction over wetlands may define and describe wetlands in a different manner than that used in this inventory. There is no attempt, in either the design or products of this inventory, to define the limits of proprietary jurisdiction of any Federal, State, or local government or to establish the geographical scope of the regulatory programs of government agencies. Persons intending to engage in activities involving modifications within or adjacent to wetland areas should seek the advice of appropriate Federal, State, or local agencies concerning specified agency regulatory programs and proprietary jurisdictions that may affect such activities. Acknowledgement of products derived from this data set should cite the following: The source of the National Wetlands Inventory data is the North Carolina Corporate Geographic Database. Earlier versions of this dataset may exist. The user must be sure to use the appropriate data set for the time period of interest. While efforts have been made to ensure that these data are accurate and reliable within the state of the art, CGIA cannot assume liability for any damages or misrepresentation caused by any inaccuracies in the data or as a result of changes to the data caused by system transfers. Although every effort has been made to ensure the accuracy of information, errors and conditions originating from physical sources used to develop the corporate database may be reflected in the data supplied. The requesting agency, corporation, or person(s) must be aware of data conditions and ultimately bear responsibility for the appropriate use of the information with respect to possible errors, original map scale, collection methodology, currency of data, and other conditions specific to certain data.
9720 Executive Center Drive
>U.S. Fish & Wildlife Service, National Wetlands Inventory >Chief Cartographer >9720 Executive Center Drive >St.Petersburg >Florida > >NCCGIA Director >Database Administration, Zsolt Nagy >Database Management, Ken Shaffer >Project Manager, David Giordano >North Carolina Center for Geographic Information and Analysis >Governor's Office >Office of State Planning >301 North Wilmington Street, Suite 700 >Raleigh, NC 27601-2825
Accuracy is tested by manual comparison of the source with hard copy printouts and/or symbolized display of the digital wetlands data on an interactive computer graphic system. In addition, WAMS software (USFWS-NWI) tests the attributes against a master set of valid wetland attributes.
Polygons intersecting the neatline are closed along the border. Segments making up the outer and inner boundaries of a polygon tie end-to-end to completely enclose the area. Line segments are a set of sequentially numbered coordinate pairs. No duplicate features exist nor duplicate points in a data string. Intersecting lines are separated into individual line segments at the point of intersection. Point data are represented by two sets of coordinate pairs, each with the same coordinate values. All nodes are represented by a single coordinate pair which indicates the beginning or end of a line segment. The neatline is generated by connecting the four corners of the digital file, as established during initialization of the digital file. All data crossing the neatline are clipped to the neatline and data within a specified tolerance of the neatline are snapped to the neatline. Tests for logical consistency are performed by WAMS verification software (USFWS-NWI). Once the 7.5 minute extents are map joined into river basin extents, the data is built for topology. No edits have been made since the last build or clean.
All photo-interpretable wetlands are mapped. In the treeless prairies, 1/4 acre wetlands are mapped. In forested areas, small open water and emergent wetlands are mapped. In general, the minimum mapping unit is from 1 to 3 acres depending on the wetland type and the scale and emulsion of the source aerial photography. In regions of the country where evergreen forested wetlands predominate, wetlands smaller than 3 acres may not be mapped. Thus, a detailed on the ground and historical analysis of a single site may result in a revision of the wetland boundaries established through photographic interpretation. In addition, some small wetlands and those obscured by dense forest cover may not be included in this dataset.
The positional accuracy of the data delivered by the NWI program is significantly altered at CGIA. This data was reprojected to NAD83, State Plane, Meters using ESRI's projection routine in ARC/INFO version 7.2.
Wetlands spatial and attribute information. Scales range from 1:20,000 to 1:132,000 and includes black and white, color infrared, or natural color aerial photograph film transparency. Sources vary by quadrangle.
Base cartographic data
Wetlands locations and classification
Digital files were converted in projection, datum, and measurement units, and map joined to river basin map extents and are stored as a map library.
NWI maps are compiled through manual photointerpretation of NHAP or NAPP aerial photography supplemented by Soil Surveys and field checking of wetland photo signatures. Delineated wetland boundaries are manually transferred from interpreted photos to USGS 7.5 minute topographic quadrangle maps and then manually labelled. Quality control steps occur throughout the photointerpretation, map compilation, and map reproduction processes. NWI1 and NWI2 data were used in this 1994 process. Digital wetlands data are either manually digitized or scanned from stable-base copies of the 1:24,000 scale wetlands overlays registered to the standard U.S. Geological Survey (USGS) 7.5 minute quadrangles into topologically correct data files using Wetlands Analytical Mapping System (WAMS) software. Files contain ground planimetric coordinates and wetland attributes. The quadrangles were referenced to the North American Datum of 1927 (NAD27) horizontal datum. The scanning process captured the digital data at a scanning resolution of at least 0.001 inches; the resulting raster data were vectorized and then attributed on an interactive editing station. Manual digitizing used a digitizing table to capture the digital data at a resolution of at least 0.005 inches; attribution was performed as the data were digitized. The determination of scanning versus manual digitizing production method was based on feature density, source map quality, feature symbology, and availability of production systems. The data were checked for position by comparing plots of the digital data to the source material.
9720 Executive Center Drive
US Fish and Wildlife Homepage functional
NWI quads were downloaded through ftp to CGIA and converted to NAD 27, stateplane, feet. They were then map joined into USGS 100 k map extent files. These had the neatlines dissovled, and the data was joined into a statewide file. This file was clipped to river basin extents and the files projected to nad83, state plane, meters. The data is stored by river basin tile in a GIS data library.
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Internal feature number.
ESRI
Total perimeter in coverage units
Software computed
Internal feature number.
ESRI
Feature geometry.
ESRI
Feature geometry.
ESRI
From-node identifier of linear feature
Software computed
To-node identifier of linear feature
Software computed
Internal number of poly to left of arc
Software computed
Internal number of poly to right of arc
Software computed
Length of arc in coverage units
Software computed
Internal feature number
Software computed
Internal identification number
User defined
Classification of the wetland
Cowardin, L.M., V. Carter, F. Golet, and E. LaRoe. 1979. Classification of wetlands and deepwater habitats of the United States. U.S. Fish Wildlife Service. 103 pp.
Classification of the wetland system. These include Marine, open ocean and associated coastline; Estuarine, salt marshes and brackish tidal water; Riverine, rivers, creeks, and streams; Lacustrine, lakes and deep ponds; Palustrine, shallow ponds, marshes, swamps, sloughs Sytems are further subdivided into subsystems which relect hydrologic conditions.
United States. U.S. Fish Wildlife Service
Classification of the wetland by appearance of the wetland in terms of vegetation or substrate.
United States. U.S. Fish Wildlife Service
Additional subclassification see citation below
United States. U.S. Fish Wildlife Service
Additional subclassification see citation below
United States. U.S. Fish Wildlife Service
Additional subclassification see citation below
United States. U.S. Fish Wildlife Service
Additional subclassification see citation below
United States. U.S. Fish Wildlife Service
Additional subclassification see citation below
United States. U.S. Fish Wildlife Service
County Federal Information Processeing Standards Code
U.S. Department of the Interior, U.S. Geological Survey
The wetland classification system is hierarchical, with wetlands and deepwater habitats divided among five major systems at the broadest level. The five systems include Marine (open ocean and associated coastline), Estuarine (salt marshes and brackish tidal water), Riverine (rivers, creeks, and streams), Lacustrine (lakes and deep ponds), and Palustrine (shallow ponds, marshes, swamps, sloughs). Systems are further subdivided into subsystems which reflect hydrologic conditions. Below the subsystem is the class which describes the appearance of the wetland in terms of vegetation or substrate. Each class is further subdivided into subclasses; vegetated subclasses are described in terms of life form and substrate subclasses in terms of composition. The classification system also includes modifiers to describe hydrology (water regime), soils, water chemistry (pH, salinity), and special modifiers relating to man's activities (e.g., impounded, partly drained). >NWI.PAT Polygon Attribute Table >COL ITEM NAME WDTH OPUT TYP N.DEC ALTERNATE NAME >1 AREA 4 12 F 3 >5 PERIMETER 4 12 F 3 >9 NWI# 4 5 B - >13 NWI-ID 4 5 B - >17 NWI-NAME 20 20 C - >37 FIPS 3 3 I - > >NWI.AAT Arc Attribute Table >COL ITEM NAME WDTH OPUT TYP N.DEC ALTERNATE NAME >1 FNODE# 4 5 B - >5 TNODE# 4 5 B - >9 LPOLY# 4 5 B - >13 RPOLY# 4 5 B - >17 LENGTH 4 12 F 3 >21 NWI# 4 5 B - >25 NWI-ID 4 5 B - >29 NWI-NAME 20 20 C - >49 NWI-SYSTEM 2 2 C - >51 NWI-CLASS 7 7 C - >58 NWI-REGIME 3 3 C - >61 NWI-TITAL 1 1 C - >62 NWI-CHEMISTRY 1 1 C - >63 NWI-SOIL 1 1 C - >64 NWI-SPECIAL 1 1 C - >65 FIPS 3 3 I -
Cowardin, L.M., V. Carter, F. Golet, and E. LaRoe. 1979. Classification of wetlands and deepwater habitats of the United States. U.S. Fish Wildlife Service. 103 pp. Photointerpretation Conventions for the National Wetlands Inventory, March 1990
301 North Wilmington Street, Suite 700
Phone and electronic mail preferred For current price information use a web browser: COST INFORMATION - http://www.cgia.state.nc.us/cost.html
NCCGIA is charged with the development and maintenance of the State's corporate geographic database and, in cooperation with other mapping organizations, is committed to offering its users accurate, useful, and current information about the state. Although every effort has been made to ensure the accuracy of information, errors and conditions originating from physical sources used to develop the corporate database may be reflected in the data supplied. The client must be aware of data conditions and bear responsibility for the appropriate use of the information with respect to possible errors, original map scale, collection methodology, currency of data, and other conditions specific to certain data. NCCGIA does not support secondary distribution of this data. The use of trade names or commercial products does not constitute their endorsement by the NCCGIA or North Carolina State Government.
Data creation and large data analysis jobs contact Database Administration P:(919)733-2090. All data is available through standard ordering procedures on a cost recovery basis.
301 North Wilmington Street, Suite 700
Phone and electronic mail preferred