Identification_Information:

Citation:

Citation_Information:

Originator:

U.S. Geological Survey, in cooperation with the Vermont State Agency of Transportation.

Publication_Date: 2003

Title: National Hydrography Dataset

Watershed Support Data Layers

Publication_Information:

Publication_Place: Reston, Virginia

Publisher: U.S. Geological Survey

Description:

Abstract:

The National Hydrography Dataset (NHD) is a feature‑based database that interconnects and uniquely identifies the stream segments or reaches that make up the nation’s surface water drainage system. NHD Watershed allows users to delineate a watershed from any point on any NHD reach in a fast, accurate, and reliable manner. NHD Watershed requires the NHD Watershed Support data layers. The NHD Watershed Support data layers can be imported into other geographic information system (GIS) data models and used for surface-water modeling applications.

Purpose:

Watershed delineation using traditional methods of manual interpretation from contour data on topographic maps can be a time consuming process. The advancement of GIS allows computer algorithms to automate the delineation of watersheds from digital elevation model (DEM) data. Computer watershed delineation from high resolution DEMs, DEMs with large areal extents, or a combination of the two factors, can increase the demands of computer resources and processing time. In certain cases, computer resource demands needed to delineate large watersheds become impractical and may even cause computer application failure. The problems posed with using high resolution/large DEM analysis areas for computer-derived watershed delineation were overcome by the State of Massachusetts MassGIS, in cooperation with the U.S. Geological Survey (USGS). Methodologies developed by MassGIS and the USGS, have been transferred and modified for use with the National Hydrography Dataset (NHD).

NHD is a comprehensive set of digital spatial data that contains information about surface water features such as lakes, ponds, streams, and rivers. In the NHD, surface-water features are combined to form "reaches," which provide the framework for linking water-related data to the NHD surface-water drainage network. The linkages enable the analysis and display of these water-related data in upstream and downstream order. For more information on NHD, go to http://nhd.usgs.gov.

NHD Watershed is an ArcView 3.x (Environmental Systems Research Institute, Inc., 1996) extension tool, which utilizes the unique linkages within NHD to quickly delineate a watershed for any point on an NHD reach. The tool requires the NHD WATershed SUPport (WATSUP) data layers along with the corresponding 8-digit subbasin NHD. The NHD WATSUP data layers are comprised of two DEM hydrologic derivative raster grids (Accum, Dir_grd), a digital data layer of sub-watersheds, called catchments (Shed_cov), and a vector dendritic stream network (Dendrite).

The NHD WATSUP dendritic network is a shapefile called Dendrite. Dendrite is used in NHD Watershed to verify the user has selected a point along an NHD reach before the tool attempts to delineate a basin. The Dendrite shapefile is created from the NHD RCH route network and contains the same attributes as NHD RCH route. The Dendrite file can be used to control where NHD Watershed works. For instance, an application built upon NHD Watershed, was developed in Vermont to estimate peak streamflow based on watershed characteristics for any selected point on an NHD reach. The Vermont regression equations used to estimate the streamflow characteristics were not designed to estimate streamflows on heavily regulated waterways such as the Connecticut River. By removing the Connecticut River reaches in the Dendrite shapefile, NHD Watershed will not allow the user to delineate a basin for a selected point along a Connecticut River reach, thus preventing the Vermont application from providing erroneous peak streamflow estimates.

The NHD WATSUP flow accumulation grid in ARC/INFO GRID format, named Accum, is a raster dataset where each grid cell value represents the total number of upland contributing flow cells. In using NHD Watershed tool, once the tool establishes that the user selected point is a valid NHD stream reach, the tool then finds the highest flow cell value in Accum to snap the start of the delineation to the selected point. The highest flow cell is found within a certain radius from the user selected point and represents the corresponding stream cell location in Accum, to the selected point on the NHD reach.

The NHD WATSUP catchment data layer is an ARC/INFO coverage named Shed_cov. Catchments in Shed_cov are delineated for each unique NHD stream reach. Since each stream reach in the NHD has a catchment associated with it, the functionality of the NHD Watershed Tool is used to help minimize the raster grid analysis area by first computing a subwatershed within the selected reach’s catchment area. NHD Watershed then merges the delineation with the results of an accumulation of upstream catchments to the selected reach.

Delineation of watersheds in catchments is accomplished by using the NHD WATSUP flow direction grid in ARC/INFO GRID format, named Dir_grd. Dir_grd is a raster-based dataset where each grid cell value represents direction of flow to its steepest neighbor (Environmental Systems Research Institute, 1999).

Dir_grd and Accum are created from a “hydrologically conditioned” DEM, modified from the National Elevation Dataset (NED) or other DEM sources. The hydrologically conditioned DEM has drainage in horizontal agreement with the NHD, and watershed divides that agree with existing watershed data such as the Natural Resources Conservation Service 12-digit Watershed Boundary Dataset (WBD). For more information about NHD Watershed and how the Watershed Support data layers were created go to http://nhd.usgs.gov/applications.html#nhdwatershed.

Reference:

Environmental Systems Research Institute, Inc., 1996, Using ArcView GIS: Redlands, Calif., 350 p.

Environmental Systems Research Institute, Inc., 1999, Using ARC GRID with ARC/INFO: Redlands, Calif., 318 p.

Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 04/24/2003

Currentness_Reference: 04/24/2003

Status:

Progress: Complete

Maintenance_and_Update_Frequency: Irregular

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -72.9813200

East_Bounding_Coordinate: -72.3142700

North_Bounding_Coordinate: 44.1070000

South_Bounding_Coordinate: 43.6645900

Keywords:

Theme:

Theme_Keyword_Thesaurus: None

Theme_Keyword: Hydrography

Theme_Keyword: National Hydrography Dataset

Theme_Keyword: NHD Watershed

Theme_Keyword: Stream / River

Theme_Keyword: Digital Elevation Model Derivatives

Theme_Keyword: Flow Direction Grid

Theme_Keyword: Flow Accumulation Grid

Theme_Keyword: NHD Catchments

Theme_Keyword: Watersheds

Theme_Keyword: Drainage Basin

Theme_Keyword: Subbasin

Place:

Place_Keyword_Thesaurus: None

Place_Keyword: Vermont

Place_Keyword: 01080105

Place_Keyword: White River Basin

Access_Constraints: None

Use_Constraints:

None. Acknowledgment of the originating agencies would be appreciated in products derived from these data.

Data_Set_Credit:

NHD WATSUP data layers for areas in Vermont developed by the U.S. Geological Survey, in cooperation with the Vermont State Agency of Transportation. For other areas in the United States, see dataset-specific metadata

Data_Qualilty_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

The NHD reach catchment data layer, Shed_cov, contains the corresponding NHD Reach Code in the NHD RCH route network. Since the catchments in Shed_cov are generated from DEM data and the unique Reach Codes found in the source NHD reaches, there is a 100% accuracy transfer of the reach codes found in NHD RCH route to the NHD WATSUP Shed_cov-catchment coverage.

Logical_Consistency_Report:

Flow direction and flow accumulation grids are spatially consistent with NHD datasets. The catchment coverage, shed_cov, is spatially consistent with WBD and NHD. For details on how these data layers were compiled, see http://nhd.usgs.gov/applications.html#nhdwatershed

Completeness_Report:

The completeness of the Dendrite shapefile reflects the content of the sources, which most often are the published USGS topographic quadrangle and (or) the U.S. Forest Service Primary Base Series (PBS) map. The USGS topographic quadrangle is usually supplemented by Digital Orthophoto Quadrangles(DOQs). Features found on the ground may have been eliminated or generalized on the source map because of scale and legibility constraints. In general, streams longer than 1 mile (approximately 1.6 kilometers) were collected. Most streams that flow from a lake were collected regardless of their length. Only definite channels were collected so not all swamp/marsh features have stream/rivers delineated through them. Note, however, that these general rules were applied unevenly among maps during compilation. Transport reaches are defined on nearly all features of type stream/river, canal/ditch, artificial path, and connector. Detailed capture conditions are provided for every feature type in the Standards for National Hydrography Dataset - High Resolution (USGS, 1999), available online at http://mapping.usgs.gov/standards/.

Catchments in Shed_cov are created for all NHD reaches except for those reaches not connected to the network in the NHD flow table, such as certain canal/ditch feature types. By excluding the delineation of catchment areas associated with non-connected network NHD reaches, the NHD Watershed tool will delineate watersheds accurately. Catchments may also be excluded for reaches that are part of a braided network. See the online document http://nhd.usgs.gov/applications.html#nhdwatershed for details on how and why braided networks may be alternatively removed during the pre-processing phase. In certain cases, when an NHD reach length is less than 10 meters, it is possible no catchment area will be generated for that reach. The exclusion of catchment areas for reaches less than 10 meters in length can be traced to the WATSUP pre-processing phase. In generating the catchment areas (Shed_cov) for the NHD reaches, the vector NHD Route RCH network is converted to a 10-meter resolution raster grid to match the cell resolution of the WATSUP flow direction grid (Dir_grd). NHD reaches less than 10 meters in length may not be converted into the raster grid model, since the length of the reach is less than the specified output 10-meter cell size for the NHD stream grid. NHD reach catchments (Shed_cov) are generated with the WATERSHED command in ARC/INFO using the WATSUP flow direction grid (Dir_grd) and the NHD stream grid.

The WATSUP Accum grid is an accumulated flow cell count, where

the total number of contributing flow cells is represented as the value for each grid cell. Accum grids for each 8-digit subbasin, are generated from a hydrologically conditioned DEM clipped to the corresponding 8-digit subbasin area. As a result of using a clipped DEM to derive Accum, the number of contributing upstream flow cells, from potential upstream 8-digit subbasin areas are not included in Accum.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

Statements of horizontal positional accuracy for the NHD WATSUP geospatial layer named Dendrite, is based on accuracy statements made for U.S. Geological Survey topographic quadrangle maps. These maps were compiled to meet National Map Accuracy Standards. For horizontal accuracy, this standard is met if at least 90 percent of points tested are within 0.02 inch(at map scale) of the true position. Additional offsets to positions may have been introduced where feature density is high to improve the legibility of map symbols. In addition, the digitizing of maps is estimated to contain a horizontal positional error of less than or equal to 0.003 inch standard error (at map scale) in the two component directions relative to the source maps. Visual comparison between the map graphic (including digital scans of the graphic) and plots or digital displays of points, lines, and areas is used as control to assess the positional accuracy of digital data. Digital map elements along the adjoining edges of data sets are aligned if they are within a 0.02 inch tolerance (at map scale). Features with like dimensionality (for example, features that all are delineated with lines), with or without like characteristics, which are within the tolerance, are aligned by moving the features equally to a common point. Features outside the tolerance are not moved; instead, a feature of type connector is added to join the features.

NHD WATSUP data derived from DEMs include the raster datasets named Dir_grd, Accum, and the vector NHD catchment coverage named Shed_cov. Horizontal accuracy statements for the source DEMs used to generate WATSUP is best described on the NED website ( http://gisdata.usgs.net/NED/AccuracyQ2.asp ):

“For the purposes of describing the horizontal accuracy of gridded digital elevation data, including NED, it is best to consider just vertical accuracy as a descriptive statistic. Horizontal errors in the source data contribute to the overall vertical error in the DEM. For example, consider the hypothetical case in which all elevations in a DEM are correct but the entire DEM is shifted horizontally from its true position. In this case, all the vertical error in the DEM is present only because of horizontal error in the source data. In reality, vertical error in the DEM is a combination of the horizontal error in the source material and the vertical error introduced by the elevation extraction and gridding processes.”

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report:

The WATSUP Dir_grd, Acum, and Shed_cov were generated from hydrologically conditioned National Elevation Dataset (NED) data and (or) other USGS DEM data. It is best to refer to the NED website (http://gisdata.usgs.net/NED/AccuracyQ2.asp) for statements of vertical accuracy for DEM data.

Source DEM data is further modified by re-interpolating the elevation points to a 10-meter resolution using 1:24,000-scale NHD stream network vector files as a drainage enforcement factor. The procedures in creating the hydrologic DEM and DEM derived NHD WATSUP are described at http://nhd.usgs.gov/watershed/watershed_tool_inst_TOC.html. No assessment of the vertical accuracy has been made for the hydrologically conditioned 10 meter DEMs, however, it is assumed that the vertical accuracy is close to that of the source USGS DEMs. The hydrologically conditioned elevation grid is not needed for NHD Watershed and is subsequently deleted once the flow direction and flow accumulation grids are derived from it.

Lineage:

Source_Information:

Source_Citation:

Citation_Information:

Originator: U.S. Geological Survey, in cooperation with U.S.

Environmental Protection Agency.

Publication_Date: 1999

Title: National Hydrography Dataset

Source_Scale_Denominator: 24000

Type_of_Source_Media: Online

Source_Time_Period_of_Content:

Single_Date/Time:

Calendar_Date: 04/22/2002 (This date should reflect when the

NHD for the WATSUP subbasin was created)

Source_Currentness_Reference: Publication date

Source_Citation_Abbreviation: NHD

Source_Contribution:

The NHD route.rch route system was converted to create the

NHD WATSUP Dendrite shapefile. The NHD streams were used

in the DEM hydrologic conditioning process. The NHD route.rch

and accompanying attributes, com_id and reach_code, were used

in the NHD reach catchment delineation.

Source_Citation:

Citation_Information:

Originator: U.S. Geological Survey

Publication_Date: 1999

Title: National Elevation Dataset

Source_Scale_Denominator: 24000

Type_of_Source_Media: Online

Source_Time_Period_of_Content:

Single_Date/Time:

Calendar_Date: 2001 – (This date should reflect when the

source NED data was obtained from USGS EROS)

Source_Currentness_Reference: Publication date

Source_Citation_Abbreviation: NED

Source_Contribution: Source digital elevation model used to

derive the NHD WATSUP Dir_grd, Accum and

Shed_cov.

Source_Citation:

Citation_Information:

Originator: U.S. Geological Survey

Publication_Date: 2001

Title: 10-meter Digital Elevation Model, 7.5 minute

Source_Scale_Denominator: 24000

Type_of_Source_Media: Online

Source_Time_Period_of_Content:

Single_Date/Time:

Calendar_Date:

Source_Currentness_Reference: 2001

Source_Citation_Abbreviation: DEM

Source_Contribution: 10-meter DEMs used in place of NED for

the Delectable Mountain, Quechee, and

Woodstock North 7.5 minute quadrangles.

Source DEMS used in conjunction with NED

to derive the NHD WATSUP Dir_grd, Accum

and Shed_cov.

Source_Citation:

Citation_Information:

Originator: Natural Resources Conservation Service

Publication_Date: unknown

Title: National Watershed Boundary Dataset

Source_Scale_Denominator: 1:24,000

Type_of_Source_Media: Online

Source_Time_Period_of_Content:

Single_Date/Time:

Calendar_Date: unknown

Source_Currentness_Reference: Publication date

Source_Citation_Abbreviation: WBD

Source_Contribution: 12-digit sub-basins used in the

DEM hydrologic-conditioning

process.

Source_Citation:

Citation_Information:

Originator: U.S. Geological Survey

Publication_Date: 2000

Title: Stream-Gaging Station Basin Boundaries

Source_Scale_Denominator: 1:24,000

Type_of_Source_Media: digital data

Source_Time_Period_of_Content:

Single_Date/Time:

Calendar_Date: 2000

Source_Currentness_Reference: 2000

Source_Citation_Abbreviation: none

Source_Contribution: Stream-gaging station boundaries used in

conjunction with WBD in the DEM

hydrologic-conditioning process.

Process_Step:

Process_Description:

See http://nhd.usgs.gov/watershed/watershed_tool_inst_TOC.html

Source_Used_Citation_Abbreviation: WBD

Source_Used_Citation_Abbreviation: NHD

Source_Used_Citation_Abbreviation: NED

Process_Date: 07/29/02

Source_Produced_Citation_Abbreviation: WATSUP

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Grid_Coordinate_System:

Grid_Coordinate_System_Name: State Plane Coordinate System 1983

State_Plane_Coordinate_System:

SPCS_Zone_Identifier: 5526 (Vermont)

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: coordinate pair

Coordinate_Representation:

Abscissa_Resolution: 10.0

Ordinate_Resolution: 10.0

Planar_Distance_Units: Meters

Geodetic_Model:

Horizontal_Datum_Name: North American Datum of 1983

Ellipsoid_Name: GRS1980

Semi-major_Axis: 6378206.4

Denominator_of_Flattening_Ratio: 294.98

Entity_and_Attribute_Information:

Overview_Description:

Entity_and_Attribute_Overview:

The National Hydrography Dataset is a comprehensive set of digital spatial data that encodes information about naturally occurring and constructed bodies of water, paths through which water flows, and related entities. For reaches, encoded information includes a reach code, the date the reach code was assigned, a unique common identifier, the reach length or area, and, for transport reaches, the stream level. Names and their identifiers in the Geographic Names Information System, are assigned to reaches.

Reach codes in shed_cov are related one-to-one with NHD reach codes (from the route.rch table). Flow direction and flow accumulation grids are used for the explicit purpose of delineating watersheds: the attributes are not used other than computationally for on-the-fly watershed delineation. NHD Watershed output (on-the-fly basin boundaries from a point) include NHD attributes reach-id, com-id, and a stream measure. The output watersheds also include a basin area.

Entity_and_Attribute_Detail_Citation:

The names and definitions of all feature types, characteristics, and values are in U.S. Geological Survey, 1999, Standards for National Hydrography Dataset: Reston, Virginia, U.S. Geological Survey. The document is available online through http://mapping.usgs.gov/standards/. Information about tables and fields in the data are available from the user documentation for the National Hydrography Dataset.

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Earth Science Information Center, U.S.

Geological Survey

Contact_Address:

Address_Type: mailing address

Address: 507 National Center

City: Reston

State_or_Province: Virginia

Postal_Code: 20192

Contact_Voice_Telephone: 1-888-ASK-USGS

Hours_of_Service: 0800-1600

Contact_Instructions:

In addition to the address above there are other ESIC offices

throughout the country. A full list of these offices is at

URL: http://mapping.usgs.gov/esic/esic_index.html

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Vermont Center for Geographic Information

(VCGI)

Contact_Address:

Address_Type: mailing address

Address: 58 South Main Street Suite 2

City: Waterbury

State_or_Province: Vermont

Postal_Code: 05676

Contact_Voice_Telephone: 1-802-882-3000

Contact_Instructions:

In addition to the address above, VCGI can be contacted online

URL: http://www.vcgi.org/.

Distribution_Liability:

Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made by the USGS regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty.

Metadata_Reference_Information:

Metadata_Date:

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Earth Science Information Center, U.S. Geological Survey

Contact_Address:

Address_Type: Mailing Address

Address: 507 National Center

City: Reston

State_or_Province: VA

Postal_Code: 20192

Contact_Voice_Telephone: 1-888–ASK-USGS

Contact_Instructions: none

Metadata_Standard_Name: FGDC Standard for Digital Geospatial Metadata

Metadata_Standard_Version: 19940608