New Documents for the National Hydrography Dataset

New DocumentsNew Documentsforfor the the

National Hydrography DatasetNational Hydrography Dataset

National Hydrography DatasetFeature Catalog

Based on 1:24,000-scale USGS Topographic Map Content

U.S. Department of the InteriorU.S. Geological Survey

AREA OF COMPLEX CHANNELS – Glacial outwash in Alaska

AREA TO BE SUBMERGEDDam under construction will create Lake Nighthorse in CO

Artificial Path – no real world image

BAY/INLET

BRIDGE – C&O Canal Carried over the Monocacy River

Los Angeles AqueductCANAL/DITCH – C/D Type = Aqueduct PIPELINE – Pipeline Type = Aqueduct; AbovegroundBoth of these features function as an aqueduct – “A structure designed to transport domestic or industrial water from a supply source to a distribution point, often by gravity” However, they have different forms. One is an “artificial open waterway…” and the other is a “closed conduit…”

Coastline

Connector

GATE

PIPELINE – Penstock above ground

PIPELINE - Elevated

PLAYA

ROCK

WATER INTAKE/OUTFLOW – Hoover Dam

San Francisco/San Pablo/Suisun Bay ESTUARYLooking south west towards the Pacific Ocean

San Francisco/San Pablo/Suisun Bay Estuary – currently coded as SEA/OCEAN (grey-blue) in the NHD. New guidance for delineation of ESTUARY would separate the ESTUARY from SEA/OCEAN as shown by the solid green line(approximately the Golden Gate Bridge). Pink straight line indicates line of sight from the photo. The red line in the Pacific Ocean is the three-mile limit. This is the preferred limit for SEA/OCEAN – current limit of SEA/OCEAN is the edgeof the USGS quadrangle maps – hence the straight lines.

Hassayampa River - WASH

In the NHD, WASHES are delineated only as areas. If there is no perennialchannel within the wash, ARTIFICIAL PATHS are added to allow flow through the network.

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National Hydro DatasetData Dictionary

Data Model version 1.06


Remember to show the document to the Stewards

Field Name Definition Applies to Comments

ComID 10-digit integer that uniquely identifies the occurrence of each feature.

All feature classes

National Database key. All maintenance activities depend on this ID.

FDate Date of last feature modification. All feature classes

Resolution Source resolution. Currently NHD is available as separate resolutions. Plans are to develop a single-resolution database holding the highest resolution data with tools to allow for generalization

All feature classes

Domain of values:Local >1:12,000High 1:24,000/12,000Medium 1:100,000

GNIS_ID Unique identifier assigned by GNIS, length 10.

All feature classes

GNIS_ID = “null” if no name associated with the feature

GNIS_Name Proper name, specific term, or expression by which a particular geographic entity is known, length 65.

All feature classes

GNIS_Name = “null” if no name associated with the feature

LengthKM Length of linear feature based on Albers Equal Area, length 8.

NHDFlowlineNHDLine

Computed

AreaSqKm Area of areal feature based on Albers Equal Area, length 8.

NHDAreaNHDWaterbody

Computed

Elevation The vertical distance from a given datum.

NHDAreaNHDWaterbody

Stage of the water elevation is encoded in the FCode.

ReachCode Unique identifier composed of two parts. The first eight digits is the subbasin code as defined by FIPS 103. The next six digits are randomly assigned, sequential numbers that are unique within a subbasin, length 14.

NHDFlowlineNHDWaterbodyNHDPoint

Required for all NHDFlowlines. NHDWaterbody and NHDPoint feature classes allow reach codes, but does not require them.

FlowDir Direction of flow relative to coordinate order, length 4.

NHDFlowline Domain of values:With digitizedUninitialized

WBAreaComID

The ComID of the waterbody through which the Flowline flows.

NHDFlowline Only applies to Artificial Path

FType Three-digit integer value; unique identifier of a feature type.

All feature classes

Click here for the feature catalog

FCode Five-digit integer value; composed of the feature type and combinations of characteristics and values.

All feature classes

Click here for the feature catalog

National Hydro DatabaseStewardship Handbook

Review DraftPlease send comments to:Keven [email protected]


Things to come

Metadata

Data in Previous Slide shows edits (in pink) in 11110104

Metadata record for the updates shown in previous slide is:“Update high-resolution NHD for Benton and Washington Counties, AR from 25ft LIDAR derived DEM and 6in and 12in ortho-imagery, dated 2004 and 2006. This process started with current high resolution USGS NHD geodatabase files. These data were downloaded, extracted and reprojected to NAD 83 State Plane Arkansas N. Next, the NRCS 10-digit Hydrologic Unit Code (HUC) boundary was obtained from GeoStor <http://www.geostor.arkansas.gov/>, Arkansas official geodata clearinghouse. The HUC boundary was projected to the State Plane projection and used, in part, to determine the true spatial extent of 8-digit HUC (Sub-basin) boundaries with Benton and Washington Counties. Next, hydrological analyses were performed on a 25ft LIDAR derived DEM using ArcInfo 9.1 hydrologic tools. The 25ft DEM was generated by the Center for Advanced Spatial Technologies (CAST) at the University of Arkansas using a bare earth point cloud obtained from Landair Mapping, Inc as part of the August 2004 LIDAR acquisition (Washington & Benton Counties, AR) coordinated by John McLarty, Elizabeth Bowen, Brian Culpepper, and Dr. Jack Cothren of the Northwest Arkansas Imagery Task Force. The purpose of hydrological analysis was to determine flow accumulation and direction throughout Benton and Washington Counties, thus providing an indicator as to the location of undocumented streams. Finally high resolution 2004 and 2006 true-color orthoimages, distributed by the Northwest Arkansas Regional Planning Commission and co-operative partners, were added to ArcMap 9.1 project file along with NHD, HUC high resolution boundaries and DEM flowpaths. Navigating between all 4 datasets, the 1D and 2D NHD features were updated to reflect temporal changes. Presence of 2D features were determined if the feature could be clearly seen to have area in either the 2004 or 2006 orthoimages when the screen was set to a scale of 1:4,800. Once identified, a polygon boundary was drawn, or updated, to show the feature at its high water mark (its greatest area in either of the available orthoimages). 1D features were identified using a combination of flow accumulation values (determined by DEM hydrological analyses) and supporting visual data in the orthoimagery (i.e. location of vegetative stream buffers), and drawn or updated accordingly. Consultation with the USGS concluded that undocumented streams would most likely occur in areas where the flow accumulation value was >2000 (greater than 2000 upslope pixels); therefore, areas having a value of <2000 were rarely considered for possible streams. All new 1D and 2D features were assigned feature codes (fcodes) in accordance to USGS NHD definitions, along with new reach codes.”

This metadata record was automatically generated by the disconnected edit check-in program because no metadata was supplied.

NHD Update

Update Lines based on 2002 Photography