The Nation Needs The National

Map

Governments depend on a common set of

base geographic information as a tool for

economic and community development,

land and natural resource management, and

health and safety services. Emergency

management and homeland security

applications rely on this information.

Private industry, nongovernmental

organizations, and individual citizens use

the same geographic data. Geographic

information underpins an increasingly large

part of the Nation's economy.

Available geographic data often:

Do not align with each other because 

layers are frequently created or revised 

separately,

Do not match across administrative 

boundaries because each producing 

organization uses different methods and 

standards, and

Are not up to date because of the 

complexity and cost of revision.

The U.S. Geological Survey (USGS) is

developing The National Map as a

seamless, continuously maintained, and

nationally consistent set of online, public

domain, geographic base information to

address these issues. The National Map

will serve as a foundation for integrating,

sharing, and using other data easily and

consistently.

In collaboration with other Federal, State,

county, and local government agencies, the

private sector, academia, and the public,

the USGS will coordinate, integrate, and,

where needed, produce and maintain base

geographic data.

The National Map will include digital

orthorectified imagery, elevation data,

vector data for hydrography, transportation,

boundary, and structure features,

geographic names, and land cover

information. The data will be the source of

revised paper topographic maps.

The National Hydrography Dataset

The National Hydrography Dataset (NHD)

is the surface water feature data component

of The National Map. The initial

implementation of the NHD was produced

by combining the geometry of water

features from USGS digital line graph data

with river reach codes and other

information developed by the

Environmental Protection Agency (EPA).

The USGS and the EPA are committed to a

long-term partnership to improve and

maintain the NHD. It includes information

about naturally occurring and constructed

bodies of water, paths through which water

flows, and related entities. Attributes are

attached to the feature information to

convey classification (for example,

perennial and intermittent), geographic

name, position, length, area, and water

flow direction. A reach code assigned to

each feature uniquely identifies that feature

and is a link through which other

information can be related to the NHD. In

addition to this geographic information, the

dataset contains metadata and information

that supports future updates and

improvements to the data.

NHD data support numerous hydrographic

applications, such as the following:

C Making maps. Positional and 

descriptive data in the NHD enable users 

to plot and symbolize features.

C Geocoding observations. The NHD 

reach codes serve as "stream addresses" 

to link other attribute information and 

related features to NHD features.

C Modeling. Information about the 

direction of waterflow, when combined 

with other data, enables users to model 

the transport of materials, such as 

contaminants, in hydrographic networks.

C Data maintenance. The visions of The 

National Map include partnerships to 

share the responsibilities for improving 

and updating geographic data such as 

the NHD. Unique identifiers and other 

information encoded in the NHD help to 

overcome technical problems of shared 

data maintenance.

Data Availability and Plans

The initial implementation of the NHD was

based on the delineations of water features

from 1:100,000-scale USGS topographic

maps and the EPA's Reach File Version 3.

Thus the content is cartographic in that

features may be generalized in shape and

complexity, displaced to accommodate

other content, combined, and/or dropped

U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet 060-02

June 2002

The National Map - Hydrography 
owing to the space constraints of the

medium-scale maps. 

High-resolution data, typically developed

from 1:24,000-scale USGS topographic

maps (1:63,360-scale in Alaska), 1:12,000-

scale digital orthophotos, or larger scale

sources provided by local cooperators, are

being developed according to the

availability of matching resources from

NHD partners.

Among Federal agencies, Department of

the Interior Bureaus support the

development of high-resolution data

through the High-Priority Digital Base

Data Program managed by the USGS.

Much of this work has been dedicated to

coverage of Alaska. The U.S. Forest

Service (USFS) is working with the USGS

to develop high-resolution data for national

forests. State agencies in California,

Colorado, Florida, Georgia, Indiana,

Kansas, Kentucky, Maine, Minnesota,

Missouri, Nebraska, New Jersey, North

Carolina, Ohio, Texas, Utah, Vermont, and

West Virginia are partnering with the

USGS to develop high-resolution data for

parts of all of their States. Much of the

USGS and USFS work is done under

contract with the private sector, adding

options for other organizations to develop

and maintain the NHD.

Partnership Opportunities

Organizations interested in partnering with

the USGS to develop high-resolution data

for the NHD sould contact the USGS

mapping liaison in their State. The list of

liaisons is available at

mapping.usgs.gov/www.partnrs/

crreps.html.

Information

Further information about The National

Map and the NHD is available from the

Cooperative Topographic Mapping

Program, Mail Stop 511, USGS National

Center, 12201 Sunrise Valley Drive,

Reston, VA 20192.

For information on other USGS products

and services, call 1-888-ASK-USGS or

visit the general interest publications Web

site on mapping, geography, and related

topics at

mac.usgs.gov/mac/isb/pubs/pubslists/.

For additional information, visit the

ask.usgs.gov Web site or the USGS home

page at www.usgs.gov. For more

information on hydrography, visit the NHD

web site at nhd.usgs.gov.

National Hydrography Dataset features include points, lines, and areas that represent standing and flowing surface water. Artificial paths are implied connections

that provide continuity for modeling waterflow.

Comparison of medium-resolution NHD data (thin lines) and content added in high-resolution NHD data

(thick lines). Big Sandy, Kentucky, subbasin.