The following tools are provided to assist in the use of NHD data. Any problems encountered when using these tools should be reported to firstname.lastname@example.org. No special tool is needed to display or work with the NHD other than a GIS. The NHD is a GIS dataset available in a shapefile format. Any GIS that can read shapefiles can be used to display the NHD. Some features of the NHD, such as geometric navigation, only work within the Esri ArcMap software. An alternative to working with a GIS is to display the NHD in The National Map Viewer on the web. To do this, click on Get Data > Go to the NHD Viewer.
NHD GeoConflation Tool
The GeoConflation Tool is one of several possible methods available to update the National Hydrography Dataset (NHD). The tool was originally developed to automate the “NHD Create Process” used to generate the high-resolution (1:24,000-scale) NHD data from the medium-resolution (1:100,000-scale) data. NHD GeoConflation is the combination of components from two databases into a single database. The basic goal of conflation is to conserve reach codes and unique identifiers from the USGS NHD Production data. The original attribution (or SOURCE) is transferred to the new geometry contained in a TARGET dataset by means of spatial location. So far that is normal conflation as far as GIS systems are concerned, but the tool also enforces the business rules of the NHD model and creates a history of the reach code transfers via the reach cross reference table. This is why it is referred to as GeoConflation.
One way to think of the process is "change detection and displacement.” Two datasets are used by the tool: the SOURCE which contains the current production geometry and attribution, and a new database of geometry with minimal attribution, called the TARGET. The SOURCE data is then spatially compared to the TARGET data. Where the geometries of flow lines (streams, rivers, canals, etc.) and water bodies (lakes, reservoirs, estuaries) match within specified tolerances, then attribution is automatically transferred. Close matches are flagged for review by the editor to determine if there is an actual match or not. If the feature exists in the original, but not in the target, the original feature is marked as a “missed feature,” which would ultimately lead to the feature being removed from the production data. In the alternative circumstance where the feature exists in the target but not the source, a new ReachCode is applied to the feature and a “create new feature” is automatically generated.
As in any update process the results of the output are only as good as the input. So a majority of the work is actually done during the preparation of the TARGET dataset. The updated geometry, TARGET data, must have feature types/codes, connectivity and flow direction for flow lines, and be in the correct the NHD schema in order to be used in the GeoConflation process. The end result of the process is a dataset consisting of the new geometry complete with reach codes and unique identifiers where needed. All changes to the original data will have been tracked within the model schema. In addition, the target data must pass required QA/QC checks before the final data is integrated into the NHD production database.
For more information about NHD GeoConflation, contact Partner Support through NHD-GCT@usgs.gov or contact your regional Partner Support Point of Contact.
USFS Reprojection Tool Version 2.2
The USFS Reprojection Toolbar Version 2.2 changes geographic projection and can transform Datums using ESRI ArcObjects model algorithms. It was developed by the USDA-Forest Service for the National Hydrography Dataset (NHD) NHDinGEO format, but can function on any personal or file Geodatabase. This is an add-on toolbar written for ESRI's ArcGIS 10. The advantage is that it reprojects whole Personal and File Geodatabases at once, and updates the metadata at the Geodatabase, Dataset, and Feature class levels in both the Data Quality and Spatial Reference sections of standard FGDC metadata--or creates its own metadata if there is none. Version 2.2 works on ArcGIS 10.
Developer: U.S. Forest Service - Natural Resource Information System
Contact: Brian Sanborn, Project Manager, USDA Forest Service, NRM / email@example.com / 541-750-7151
Software Environment: ArcGIS 10 (Also required: Microsoft .NET Framework version 2.0 and at least MSN Installer 3)
Purpose: The USFS Reprojection Toolbar changes geographic projection and can transform Datums using ESRI ArcObjects model algorithms. This is an add-on toolbar written for ESRI's ArcGIS 10. Once a Geodatabase is highlighted and the toolbar's button is pushed, a user interface appears. User must name a new output Personal Geodatabase, and select the desired projection and datum. A progress report at the lower left corner of ArcCatalog shows current status at all times during processing. FGDC compliant metadata is updated in both the Data Quality Information and the Spatial Reference Information sections. To reproject, the NHD network must be deleted first and then rebuilt after the reprojection is complete. The "NHD Network Builder" can be downloaded at: https://nhd.usgs.gov/tools.html#network .
Loading and Installing:
Get the appropriate version at ftp://ftpext.usgs.gov/pub/cr/mo/rolla/nhd/USFS_Reprojection_Tools.zip
For more information on ESRI AddIns http://blogs.esri.com/Dev/blogs/arcgisdesktop/archive/2010/05/05/Add_2D00_ins-for-ArcGIS-Desktop-10.aspx
Policy for linking to non-USGS sites and non-endorsement of non-USGS products and services: http://www.usgs.gov/laws/info_policies.html#nonusgs
Hydrography Event Management Tool
The Hydrography Event Management (HEM) Tool provides functionality for adding and editing events on the NHD. Events are hydrographically linked data that are referenced to the NHD using a linear referencing system on NHDFlowlines. Events allow scientific information to be linked to the NHD without altering it. The ability to locate events on the flowline network is key characteristic of the NHD. The HEM tool handles all the linear referencing mechanics to make working with events easy. HEM can make events on point, flowline, and waterbody feature of the NHD. HEM allows events to be located interactively, imported, or calculated. An editable “Source Feature ID” field provides the link between the event location and the informational data tied to the location. HEM also provides powerful feature-level metadata editing tools. Finally, HEM has the ability to measuring distances from a point through the NHDFlowline network. The most current version of the tool is for ArcGIS 10.5.1 and NHD version 2.2.1.
Click here for previous HEM versions.
HEM Support and Training
To download more training materials and other resources, visit the HEM pages at the USGS Hydrographic Data Community.
For more information about the HEM Tool, or to request personal training please contact HEM@usgs.gov.
HEM Training Materials
NHD UtilitiesArcGIS 10.5.1: NHD Utilities v220.127.116.11
Versions prior to the posted version are unsupported. If users need previous versions of the NHD Utilities contact firstname.lastname@example.org.
NHD Build Flow: The NHD Build Flow utility requires the input of an NHD subbasin personal or file geodatabase. The tool builds a geometric network using the NHDFlowline feature class within the geodatabase. Each node within the geometric network represents a confluence of two or more hydrography features less than 40 feet wide. The Build Flow utility then uses these nodes to populate the NHDFlow table with in and out flow directions for each node, based off the FlowDir attribute within the NHDFlowline feature class. The result is a populated NHDFlow table that shows the flow of water throughout the subbasin.
NHD Network Builder: The NHD uses a utility geometric network within the ESRI geodatabase. This network allows the user to use ESRI’s Utility Network Analyst extension to perform certain analysis techniques. This network must be deleted when performing edits or re-projecting the NHDFlowline feature class. After re-projecting or altering NHDFlowline data, it is necessary to re-build the geometric network to restore flow and directionality to work with Utility Network Analyst. Network Builder is a tool that rebuilds the geometric network and sets the flow direction within the context of the FlowDir attribute. The tool does not rebuild or update the NHD Flow table. The NHD Network Builder will work to build an ESRI Personal-Geodatabase (mdb) or File-Geodatabase (gdb) utility network.
M-Value Utilities: M-Values, or measures, are the percentage upstream from a given location based on the features reach code on an NHDFlowline. Measures range from 0-100 percent with 0 being the most downstream point of a reach, and 100 being the most upstream end of the reach. This is opposite of the flow/digitized direction of the feature. The M-Value Utility assigns measures to reached flow lines only. Each reached feature will have measure associated with the reach code assigned to that feature. The M-Value provides the networked location of a point event or the extent of a linear event along a reach.
PGDB2Shp: This utility will convert a NHD ESRI personal or file geodatabase into a set of shapefiles and DBF tables which can then be used by other software. The output is stored under a specific folder directory specified by the user’s system environment variables. Please read the NHD Utilities User Guide in order to obtain more information.
Shp2PGDB: This utility will convert a series of ESRI Shapefile and DBF tables that are stored in and NHD format to an ESRI personal or file geodatabase. The input must be correctly formatted and located in the user’s system environment variables folder on order to be converted. Please read the NHD Utilities User Guide in order to obtain more information.
Subset by Polygon: The Subset by Polygon tool allows a user to create a subset of NHD data from any size NHD geodatabase either in personal of file format. The tool uses a CustomArea polygon to define the area of interest (AOI) and will extract all features of the Hydrography feature dataset that intersect the AOI or have the same reachcodes as the intersecting features, allowing the user to see the full extent of the reachcode he is interested in.
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