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Hydrography Standards and Specifications

This page contains resources about the USGS National Geospatial Program’s Hydrography specifications, including 3D Hydrography Program (3DHP) product specifications, Elevation-derived Hydrography (EDH) data acquisition specifications, as well as product specifications for the legacy National Hydrography Dataset (NHD), the NHDPlus High Resolution (NHDPlus HR), and the Watershed Boundary Dataset (WB

3D Hydrography Program (3DHP) Products

3D Hydrography Program (3DHP) products contains derived water features based on elevation data, non-elevation derived data from cooperators, and data from the National Hydrography Dataset (NHD). This specification provides definitions and technical details of feature attributes. Please visit this website for more information about the 3DHP.

Elevation-derived Hydrography

Elevation-Derived Hydrography is hydrography derived directly from elevation data, providing the best possible horizontal and vertical fit between they hydrography and the elevation data it was derived from. The USGS has published the Elevation-Derived Hydrography Data Acquisition Specifications  and the Representation Extraction Attribution and Delineation Rules as guidance for delineating elevation-derived hydrographic features for the NHD. 

Legacy Products

National Hydrography Dataset

The National Hydrography Dataset (NHD) standards are composed of a three primary references: 

1) The Geographic Information Framework Data Content Standard, Part 6: Hydrography (FGDC-STD-014.6-2008) provides a conceptual framework for hydrography, but does not specifically define the NHD. The primary purpose of this part of the document is to support the exchange of surface water (hydrography) data, seeking to establish a common baseline for the semantic content of hydrography databases for public agencies and private enterprises. It also seeks to decrease the costs and simplify the exchange of hydrography data among local, Tribal, State, and Federal users and producers. That, in turn, discourages duplicative data collection. Benefits of adopting this part of the standard also include the long-term improvement of the geospatial hydrography data through the establishment of Web data services for hydrography data and maps within the community. 

2) The NHD is an implementation of this standard, and is defined through a data model.  The current data model is the National Hydrography Dataset (NHD) Model V2.3.1. The data model is a holistic view of the the entire NHD database, including an overview of the database structure, feature classes, event feature classes, attribute tables, domains, and feature-level metadata. 

3) The NHD Data Dictionary contain descriptions of the features classes, tables, coded value domains, and feature rules. 

Additionally, a draft version of Standards for National Hydrography Dataset (1999) is provided here as background information, but is not applicable to use as current NHD specification information. 

Use of the National Hydrography Dataset Specifications 

The NHD is a digital geospatial dataset.  For it to be distributed, maintained, and updated from a national data repository, it must conform to a standardized structure, contain standardized values, hold only valid relationships, and represent only approved content.  All operational phases are managed by customized software that enforce the standards, making it impossible to alter the national NHD database outside of this environment.  All NHD datasets are “stamped” with a Version Number and a Schema Version (Model Identifier) found in the NHD Processing Parameters table associated with the data. The standards also contain judgment criteria that cannot be enforced by a software system.  For example, a Lake/Pond may be incorrectly delineated and not conform to the standard outlined in the NHD Feature Catalog.  These types of issues fall under the domain of quality assurance, using standards as a reference. Quality assurance is accomplished through training and controlled editing. The USGS has conducted hundreds of training seminars throughout the life of the NHD. In order to build or maintain NHD data, all editors must use an accredited set of tools that are only able to access after completion of an NHD training curriculum. 

NHDPlus High Resolution

NHDPlus High Resolution (NHDPlus HR) documentation includes a posters of the NHDPlus HR Data Model v1.0 and NHDPlus HR Vector Processing Unit (VPU) Distribution Data Model v.2.0 with details on dataset structure, feature classes, domains, and relationships, and a User’s Guide for the National Hydrography Dataset Plus High Resolution.

Watershed Boundary Dataset

The Watershed Boundary Dataset (WBD) standards are published as Federal standards and procedures for the National Watershed Boundary Dataset (WBD), Techniques and Methods 11-A3. The current data model for the WBD is the Watershed Boundary Dataset (WBD) Data Model V2.3.1. The WBD Data Dictionary contains descriptions of the features classes and tables.