FLORIDA GEOGRAPHIC DATA LIBRARY DOCUMENTATION
VERSION 2005
TITLE: NATIONAL HYDROGRAPHY DATASET (NHD) - REACHES
Geodataset Name: NHDRCH Geodataset Type: SHAPE Geodataset Feature: LINE
GENERAL DESCRIPTION:
This dataset contains the spatial extent of reaches for the National Hydrography Dataset (NHD) in the State of Florida. The lines are features that comprise the surface water drainage network and coastline-stream/river, canal/ditch, artificial path,connector, and pipeline. The lines representing networkfeatures, through which water flows in a known direction, are oriented in the direction of flow. The lines representing coastlines are usually oriented so that the sea or ocean is to the right.
DATA SOURCE(S): United States Geological Survey SCALE OF ORIGINAL SOURCE MAPS: 1:100,000 DATE OF AUTOMATION OR SOURCE: 1999 GEODATASET EXTENT: State of FloridaFEATURE ATTRIBUTE TABLES:
Datafile Name: NHDRCH.DBF ITEM NAME WIDTH TYPE PRECISION SHAPE 9 SHAPELINE 0 COM_ID 10 LONG 0 RCH_CODE 14 CHARACTER 0 RCH_DATE 8 CHARACTER 0 LEVEL 5 DECIMAL 0 METERS 12 FLOAT 0 GNIS_ID 8 CHARACTER 0 NAME 99 CHARACTER 0 FTYPE 24 CHARACTER 0 FCODE 5 DECIMAL 0 DESC 130 CHARACTER 0 DESCRIPT 24 CHARACTER 0
FEATURE ATTRIBUTE TABLES CODES AND VALUES:
ITEM ITEM DESCRIPTION SHAPE Data attribute inherent to the ESRI shapefile format, which defines the data as a point, polyline, or polygon. COM_ID Unique common identifier of the NHD feature or reach RCH_CODE Unique identifier, 14 digit code with two parts First 8 digits - Hydrologic Unit, code for the cataloging unit in which the reach exists. Hydrologic units provide a systematic means of identifying and subdividing river-basin units. Cataloging unit is the fourth- level subdivision of hydrologic units. Last 6 digits - Assigned in sequential order, and arbitrarily among the reaches. RCH_DATE Date the RCH_CODE was assigned LEVEL Stream level which is the main path to which a transport reach belongs. It has a value range of 1 to 99 and the value -9998 for "unspecified". METERS Length of the NHD feature, in meters GNIS_ID GNIS identifier of the waterbody reach name. A "blank" means that the name is not populated. GNIS is an 8-digit code from the Geographic Names Information System developed by the USGS and the USBGN. The Federally recognized name of each feature described in the data base is identified, and references are made to a feature's location by State, county, and geographic coordinates. NAME Text of the reach name. A "blank" means that the name is not populated. FTYPE Features are classified by type. These feature types provide the basic description of the features. Each type has a name and a definition. STREAM/RIVER - A body of flowing water. LAKE/POND - A standing body of water with a predominantly natural shoreline surrounded by land. CANAL/DITCH - An artificial open waterway constructed to transport water, to irrigate or drain land, to connect two or more bodies of water, or to serve as a waterway for watercraft. CONNECTOR - A known, but nonspecific, connection between two nonadjacent network segments. ARTIFICIAL PATH - An abstraction to facilitate hydrologic modeling through open water bodies and along coastal and Great Lakes shorelines and to act as a surrogate for lakes and other water bodies. PIPELINE - A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. FCODE A five-digit feature code encodes the feature type and combinations of characteristics and values that can be assigned to a type. The first three digits encode the feature type, and the last two digits encode a set of characteristics and values. The general format of the feature code is FFFCC, in which FFF is the three-digit code for a feature type. CC is the two-digit code for a combination of values for characteristics associated with a feature type. If only the feature type is identified, these last two digits are assigned the value "0". DESC The description field uses a single character string to encode one or more characteristics and values for each feature code. The general format of the character string is characteristic|value, in which "characteristic" is the name of the characteristic. The vertical line character ("|") separates the characteristic and value. "Value" is the value of the characteristic for the feature code. DESCRIPT FGDL added item based on the item FTYPE
USER NOTES:
Please note that the NHD is designed to have many users nation wide that use as well as update the dataset. By using the data set in shapefile format it will no longer be possible to update the NHD. For information on how you can take part in the updating of NHD data, or how to get the latest version, see their website: http://nhd.usgs.gov The NHDRCH dataset is a combination of the Drain and Reach datasets taken from the NHD. The two datasets were nearly identical so the attributes from the Reach dataset was joined to the Drain dataset to form NHDRCH. In order to get flow direction information it is necessary to link the flow table to NHDRCH.shp. This table needs to be linked based on the following: For incoming flow: link "COM_ID" (NHDRCH.shp) to "COM_ID_2" (flow table) For outgoing flow: link "COM_ID" (NHDRCH.shp) to "COM_ID_1" (flow table) more information on this process can be found at http://nhd.usgs.gov/techref.html The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that comprise the nations surface water drainage system. It is based initially on the content of the U.S. Geological Survey 1:100,000-scale Digital Line Graph (DLG) hydrography data, integrated with reach-related information from the U.S. Environmental Protection Agency Reach File Version 3.0 (RF3). More specifically, it contains reach codes for networked features and isolated lakes, flow direction, names, stream level, and centerline representations for areal water bodies. Reaches are also defined to represent waterbodies and the approximate shorelines of the Great Lakes, the Atlantic and Pacific Oceans, and the Gulf of Mexico. The NHD also incorporates the National Spatial Data Infrastructure framework criteria set out by the Federal Geographic Data Committee. The National Hydrography Dataset combines elements of the DLG and RF3: spatial accuracy and comprehensiveness from the DLG and network relationships, names, stream level, and a unique identifier (reach code) for surface water features from RF3. The NHD supersedes DLG and RF3 by incorporating them, not by replacing them. Users of DLG and RF3 will find the National Hydrography Dataset both familiar and greatly expanded and refined. The NHD provides a national framework for assigning reach addresses to water-related entities, such as industrial dischargers, drinking water supplies, fish habitat areas, wild and scenic rivers. Reach addresses establish the locations of these entities relative to one another within the NHD surface water drainage network in a manner similar to street addresses. Once linked to the NHD by their reach addresses, the upstream/downstream relationships of these water-related entities and any associated information about them can be analyzed using software tools ranging from spreadsheets to geographic information systems (GIS). GIS can also be used to combine NHD-based network analysis with other data layers, such as soils, land use and population, to help better understand and display their respective effects upon one another. Furthermore, because the NHD provides a nationally consistent framework for addressing and analysis, water-related information linked to reach addresses by one organization (national, state, local) can be shared with other organizations and easily integrated into many different types of applications to the benefit of all. The National Hydrography Dataset is designed to provide comprehensive coverage of hydrologic data for the U.S. While initially based on 1:100,000-scale data, the NHD is designed to incorporate - and encourage the development of - higher-resolution data required by many users. It will facilitate the improved integration of water-related data in support of the application requirements of a growing national user community and will enable shared maintenance and enhancement. For further research of NHD item definitions go to the "National Hydrology Dataset, Contents and Concepts" at: http://nhd.usgs.gov/chapter1/index.html#_toc474479742 Certain scale datasets are not suitable for some project, analysis, or modelling purposes. Please be sure you are using the best available data. 1:24000 scale datasets are recommended for projects that are at the county level. 1:24000 data should NOT be used for high accuracy base mapping such as property parcel boundaries. 1:100000 scale datasets are recommended for projects that are at the multi-county or regional level. 1:250000 scale datasets are recommended for projects that are at the regional or state level or larger. Vector datasets with no defined scale or accuracy should be considered suspect. Make sure you are familiar with your data before using it for projects or analyses. Every effort has been made to supply the user with data documentation. For additional information, see the References section and the Data Source Contact section of this documentation. For more information regarding scale and accuracy, see our web pages at: http://www.geoplan.ufl.edu/education.html These data are based on interpretation of available information and should not be construed as legally binding.
FGDL QUALITY ASSURANCE STATUS:
-Reprojected data to FGDL Albers HPGN (See "Map Projection Parameters" below) -Upcased all character records -Joined NHD.drain to NHD.reach -Changed original file name from "nhd" to "nhdrch" -Joined shapefile with FCODE table -Renamed DESCRIPT field to DESC -DESCRIPT item was added based on the item FTYPE -Dropped old internal coverage items: RCH#, RCH_ID -Converted coverage to shapefile -Clipped shapefile to State of Florida
REFERENCES:
The United States Geological Survey and The United States Environmental Protection Agency
DATA LINEAGE SUMMARY:
The NHD is produced by a joint effort between the Environmental Protection Agency (EPA) and U.S. Geological Survey (USGS). Data was downloaded by GeoPlan in coverage format from the USGS/NHD website (http://nhd.usgs.gov/) in June 2002. When received, data was in the following projection: Geographic, Datum: NAD 83, Spheroid: GRS80, units: Decimal Degrees. The shapefile was then clipped to the State of Florida, and projected to FGDL Albers HPGN.
MAP PROJECTION PARAMETERS:
Projection ALBERS Units METERS Datum HPGN Spheroid GRS1980 1st standard parallel 24 0 0.000 2nd standard parallel 31 30 0.000 central meridian -84 0 0.000 latitude of projection's origin 24 0 0.000 false easting (meters) 400000.00000 false northing (meters) 0.00000 00000 0.00000
DATA SOURCES CONTACT(S):
Name: National Mapping Division, U.S. Department of Interior, U.S. Geological Survey Abbr.name: USGS Address: 12201 Sunrise Valley Drive Reston, VA 20192 USA Phone: 1-888-ASK-USGS (275-8747) Fax: Web site: NHD - http://nhd.usgs.gov/index.html Mapping Division - http://mapping.usgs.gov/index.html Ftp site: Email: nhd@usgs.gov
FGDL CONTACT:
Name: Florida Geographic Data Library Abbr. Name: FGDL Address: Florida Geographic Data Library 431 Architecture PO Box 115706 Gainesville, FL 32611-5706 Web site: http://www.fgdl.org Contact FGDL: Technical Support: http://www.fgdl.org/fgdlfeed.html FGDL Frequently Asked Questions: http://www.fgdl.org/fgdlfaq.html FGDL Mailing Lists: http://www.fgdl.org/fgdl-l.html For FGDL Software: http://www.fgdl.org/software.html