A data set describing the 2-dimensional spatial location of hierarchical hydrologic unit delineations based on Natural Resource Conservation Service and U.S. Geological Survey approved subbasins within or partially within a Forest Service administrative unit. Multiple subbasins are typically managed in a single data set for a Forest or administrative unit. This data is a set of merged datasets for the Southwest Region. There is a complete digital hydrologic unit boundary layer to the Subwatershed (12-digit) 6th level for the states of New Mexico, Oklahoma, Arizona, and Texas. This data set consists of geo-referenced digital data and associated attributes created in accordance with the "FGDC Proposal, Version 1.0 - Federal Standards For Delineation of Hydrologic Unit Boundaries 3/01/02" (http://www.ftw.nrcs.usda.gov/huc_data.html). Associated National Application: Natural Resource Information System (NRIS)
The Watershed and Subwatershed hydrologic unit boundaries provide a uniquely identified and uniform method of subdividing large drainage areas. The smaller sized 6th level sub-watersheds (up to 250,000 acres) are useful for numerous application programs supported by a variety of local, State, and Federal Agencies. This data set is intended to be used as a tool for water-resource management and planning activities, particularly for site-specific and localized studies requiring a level of detail provided by large-scale map information.
Outlet methodology: Outlet points were chosen by first choosing as many full stream reaches tributaries to the main stem as possible (classic watersheds). Outlets are then attempted adjacent to these classic watersheds on the main stem. Any remaining watersheds are then chosen in accordance to the next best available option.
ground condition
The distributor shall not be held liable for improper or incorrect use of this data, based on the description of appropriate/inappropriate uses described in this metadata document. It is strongly recommended that this data is directly acquired from the distributor and not indirectly through other sources which may have changed the data in some way. These data should not be used at scales greater than 1:24,000 for the purpose of identifying hydrographic watershed boundary feature locations. United States Department of Agriculture-Natural Resources Conservation Service should be acknowledged as the data source in products derived from these data. The Watershed Boundary Dataset is public information and may be interpreted by all organizations, agencies, units of government, or others based on needs; however, they are responsible for the appropriate application of the data. Federal, State, or local regulatory bodies are not to reassign to the Natural Resources Conservation Service any authority for the decisions they make. The Natural Resources Conservation Service will not perform any evaluations of these maps or purposes related solely to State or local regulatory programs. Photographic or digital enlargement of these maps to scales greater than that at which they were originally delineated can result in misrepresentation of the data. If enlarged, the maps will not include the fine detail that would be appropriate for mapping at the small scale. Digital data files are periodically updated. Files are dated, and users are responsible for obtaining the latest version of the data from the source distributor.
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100% of the attributes were visually verfied using 24K digital raster graphics (DRG's). The accuracy of this data is dependent on the level of detail of the source material and the interprtation procedures for capturing that source. Some areas required use of imagery which may differ from the DRG.
There are no unclosed polygons, intersections without nodes, or polygons without labels or with more than one label. Topology rules were defined and verified prior to certification.
All fields for all polygons in the .pat are attributed. Some polygons in the Ncontrb_a field might have a 0 value. All fields for the lines in the .aat are attributed. The lines adjacent to the universal polygon are attributed with a 0 for the hu_level. These cannot be attributed until the adjacent states complete their linework at which point the highest level of hydrologic unit can be determined.
Each state WBD was produced using Digital Raster Graphics (DRG's) as the source map. Data completeness for DRG files reflects content of the source graphic and may therefore be reflected in the completeness and accuracy of the WBD. The map was digitized from USGS 1:24,000-scale digital raster graphic base maps, with an inherited error of +/- 40 feet according to the USGS National Map Accuracy Standards. It is estimated that any errors detected were less than 10%. It should also be noted that while general rules of hydrology were used (i.e. natural water flow is downhill), the locations of boundaries is still somewhat subjective as the 1:24,000-scale DRG's do not always provide enough information for identifying the location of the boundaries. In these instances group consensus was used. Please refer to the methods section for more details on watershed delineation rules. Unquantifiable errors may be associated with coordinate shift. NAPP and NAIP Imagery were used extensively in the QA/QC process which has greater accuracy and is more current than the DRG source.
AZ watersheds
NM Watersheds
OK Watersheds
TX Watersheds
All statewide watershed shapefiles were downloaded from the geospatial data gateway website at: http://datagateway.nrcs.usda.gov/
The WBD_poly feature class was projected to Lambert, NAD83
The NM, OK, and TX shapefiles were loaded into WBD_poly
New feature classes Hydrologic_Unit_4th_Code, Hydrologic_Unit_5th_Code, and Hydrologic_Unit_6th_Code were dissolved out from WBD_poly using the HUC_8, HUC_10, and HUC_12 attribute fields
Forest Service Standard Fields were added and calculated, old fields deleted.
4th code watersheds that contain Forest Service lands were selected. 5th and 6th code watersheds within those 4th codes were also selected, the rest of the watersheds were eliminated.
None
Internal feature number.
ESRI
Feature geometry.
ESRI
Length of feature in internal units.
ESRI
Area of feature in internal units squared.
ESRI
A unique 12-digit code from the USGS map series "Hydrologic Unit Maps". The same number was used in every record that pertains to a subwatershed that resides within the same 8-digit sub-basin.
Federal Standards for Delineation of Hydrologic Unit Boundaries
A unique name for each 6th level hydrologic unit that relates to the major water feature within the polygon or the major water body it contributes to
Federal Standards for Delineation of Hydrologic Unit Boundaries
medium from which the data were created/acquired
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Original CFF
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
GPS - Uncorrected Data
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
GPS - Differentially Corrected Data
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
GPS - Survey Grade and Sub-meter
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Resurvey Plat
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Photogrammetric Compilation
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Digitized From Hardcopy PBS/SEQ
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Digitized from Hardcopy Orthophoto Quad
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Automated Land Project (ALP)
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Digitized Other
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Geographic Coordinate Database (GCDB)
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Other Cadastral Information
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Other Agency Digital
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Other
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Remote Sensing Data - Base Level
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Remote Sensing Data - Mid Level
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Remote Sensing Data - Broad Level
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Remote Sensing Data - National Level
FSH6609.15 Standards for Data and Data Structures Handbook Chapter 40
Code used to identify the method of data acquisition.
Cartographic Specifications and Symbols EM-7140-24
CFF method (digitized by GSTC)
Cartographic Specifications and Symbols EM-7140-24
GPS to vector conversion process
Cartographic Specifications and Symbols EM-7140-24
CAD to vector conversion process
Cartographic Specifications and Symbols EM-7140-24
Vectorized Raster Data
Cartographic Specifications and Symbols EM-7140-24
Other conversion to vector
Cartographic Specifications and Symbols EM-7140-24
Photogrammetric Compilation
Cartographic Specifications and Symbols EM-7140-24
Digitization hard copy data
Cartographic Specifications and Symbols EM-7140-24
On screen digitization/monoscopic interpretation
Cartographic Specifications and Symbols EM-7140-24
Scanning/Rasterization
Cartographic Specifications and Symbols EM-7140-24
Other
Cartographic Specifications and Symbols EM-7140-24
Unknown
Cartographic Specifications and Symbols EM-7140-24
Huc6 : Twelve Digit Hydrologic Unit Code - A unique 12-digit code from the USGS map series "Hydrologic Unit Maps". The same number was used in every record that pertains to a subwatershed that resides within the same 8-digit sub-basin. Numbers were assigned in an upstream to downstream fashion. Where no downstream/upstream relationship could be determined numbers were assigned in a clockwise fashion. Huc_name: Hydrologic Unit Name - This field used officially recognized names only. This field was populated by following the directions in subsection 6.3 "Watershed and Subwatershed Naming Protocol". The name used to attribute the watershed was used only once within each level unit.
Federal Standard for Delineation of Hydrologic Unit Boundaries
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The USDA Forest Service manages these data for planning purposes, not necessarily for actual on the ground implementation. The USFS is in no way condoning or endorsing the actual on the ground implementation of these data. It is the sole responsibility of the user to determine whether or not the data are suitable for the intended purpose. It is also the obligation of the user to apply these data in an appropriate and conscientious manner. The USFS provides no warranty, nor accepts any liability occurring from the use of these data.
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