Science
National Hydrography FAQs.
FAQs
How should I cite datasets and services from The National Map? How should I cite datasets and services from The National Map?
The USGS does not require a specific format when citing data obtained through The National Map. You should follow the citation guidelines provided by instructors or publication editors as appropriate. The following should help you find the information that you need: Citation for Datasets Author: U.S. Geological Survey Release date: the first four numbers of from dataset metadata for the...
What sources were used to produce the National Hydrography Dataset (NHD)? What sources were used to produce the National Hydrography Dataset (NHD)?
The National Hydrography Dataset (NHD) is a combination of USGS hydrologic digital line graph (DLG) files and Environmental Protection Agency (EPA) reach files, version 3.0 (RF3). U.S. Forest Service Cartographic Feature Files (CFF) and USGS Tagged Vector Hydro (TVH) captured from 7.5-minute printed maps were also used. Some states also contributed their own stream layer data to the compilation of...
What is the positional accuracy of the National Hydrography Dataset (NHD)? What is the positional accuracy of the National Hydrography Dataset (NHD)?
Original hydrographic data were compiled to meet National Map Accuracy standards. These standards have been maintained in the process of creating the NHD. At 1:100,000 scale, ninety percent of well-defined features are within 167 feet (0.02 inches at map scale) of their true geographic position. When higher resolution data are created and submitted, the positional accuracy may vary due to...