The National Hydrography Dataset (NHD) is a digital

database In computing, a database is an organized collection of data stored and accessed electronically. Small databases can be stored on a file system, while large databases are hosted on computer clusters or cloud storage. The design of databases sp ...

of surface

water feature In landscape architecture and garden design, a water feature is one or more items from a range of fountains, jeux d'eau, pools, ponds, rills, artificial waterfalls, and streams. Before the 18th century they were usually powered by gravity, ...

s used to make maps. It contains features such as

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

ponds A pond is an area filled with water, either natural or artificial, that is smaller than a lake. Defining them to be less than in area, less than deep, and with less than 30% emergent vegetation helps in distinguishing their ecology from t ...

streams A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a stream ...

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

canals Canals or artificial waterways are waterways or river engineering, engineered channel (geography), channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport watercraft, vehicles (e.g. ...

dams A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use ...

and

stream gage A stream gauge, streamgage or stream gauging station is a location used by hydrologists or environmental scientists to monitor and test terrestrial bodies of water. Hydrometric measurements of water level surface elevation ("stage") and/or volu ...

s for the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

Description

Cartographers can link to or download the NHD to use in their computer mapping software. The NHD is used to represent surface water on maps and is also used to perform geospatial analysis. It is a digital vector geospatial dataset designed for use in

geographic information systems A geographic information system (GIS) is a type of database containing geographic data (that is, descriptions of phenomena for which location is relevant), combined with software tools for managing, analyzing, and visualizing those data. In a br ...

(GIS) to analyze the flow of water throughout the nation. The dataset represents over 7.5-million miles of streams/rivers and 6.5-million lake/ponds.

Mapping

In mapping, the NHD is used with other data themes such as elevation, boundaries, and transportation to produce general reference maps. In geospatial analysis the NHD is used by scientists using

GIS A geographic information system (GIS) is a type of database containing Geographic data and information, geographic data (that is, descriptions of phenomena for which location is relevant), combined with Geographic information system software, sof ...

technology. This takes advantage of a flow direction network that can be processed to trace the flow of water downstream. A rich set of attributes used to identify the water features includes an identifier, the official name of the feature, the length or area of the feature, and metadata describing the source of the data. The identifier is used in an addressing system to link specific information about the water such as water discharge, water quality, and fish population. Using the basic water features, flow network, linked information, and other characteristics, it is possible to study cause and effect relationships, such as how a source of poor water quality upstream might affect a fish population downstream. The NHD is part of the

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

The National Map ''The National Map'' is a collaborative effort of the United States Geological Survey (USGS) and other federal, state, and local agencies to improve and deliver topographic information for the United States. The purpose of the effort is to prov ...

for the United States. The NHD is also linked with similar datasets representing the surface water for

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

and

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. The dataset primarily maps features a 1:24,000-scale, but in certain areas provides detail at 1:5,000-scale. A version of the NHD called the NHDPlus is integrated with elevation and other landscape data to create detailed drainage catchments and flow volume and velocity estimates for streams and rivers of the U.S. at 1:100,000-scale. This data is available from the

United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...

References

External links

* http://nhd.usgs.gov/ * http://nhd.usgs.gov/tools.html

Reading

Simley, J.D., Carswell Jr., W.J., 2009, The National Map—Hydrography: U.S. Geological Survey Fact Sheet 2009-3054, 4 p. Hydrography {{hydrology-stub