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National Streamflow Information Program (NSIP)

NSIP Goals


The NSIP plan provides for a stable, modernized streamgaging network that addresses core Federal and cooperator needs. It also provides for:

1. Stable Streamgaging Network

At the core of NSIP will be a set of USGS-funded streamgages strategically positioned across the country that are continuously operated to fulfill five Federal needs for streamflow information. These will be a permanent set of core streamgages from which streamflow information would be delivered in real time, uncompromised by changing support from funding partners.

In designing this proposed network, USGS personnel selected active USGS streamgages whenever possible. If none existed, they turned to either inactive USGS streamgages or streamgages operated by other agencies. If none of these possibilities were available, they proposed initiating a new streamgage for NSIP. In those instances where another agency's streamgages are apart of the design, the USGS would provide funding to that agency to assure that their streamgages follow NSIP requirements for data collection and data delivery.

In addition to operating these USGS-funded streamgages, the USGS would continue to work with many partners to operate additional streamgages that would provide the breadth and depth of coverage needed by the ever-growing community of data users. The full network would be cooperatively designed to meet Federal, State, tribal, and local needs.

Cooperators in other agencies have more than carried their share of the current network. Their active participation would continue to be crucial in the future but would build a more robust USGS-funded base than currently exists.

In addition to operating these USGS-funded streamgages, the USGS would continue to work with the many partners to operate additional streamgages that would provide the breadth and depth of coverage needed by the ever-growing community of data users. The full network would be cooperatively designed to meet Federal, State, tribal, and local needs.

See or click the Streamgaging Network title above to see this network on a national and state basis.

2. Floods and Droughts

The NSIP plan call for intensive data collection during major floods and droughts. This additional information is needed to provide improved estimates of risk and impacts for better hazard response and mitigation. Information collected would include systematic field surveys of precipitation, river stage, river discharge, and water quality. In addition, temporary streamgages would be deployed during floods to ensure adequate data are available for forecasting and response activities in critical locations where there are no permanent streamgages.

3. Regional and National Streamflow Assessments

Responsible water-resources planning for supply and quality must be based on knowledge of the frequency with which high and low flows occur in a given river. For example, protection of endangered aquatic species depends on know how often low flows that threaten their survivability are expected to occur.

Delineation of flood-hazard zones and design of bridges and other structures requires knowing the water level and discharge of the 100- and 200-year floods. Regional and national assessments are needed to provide this information on the frequency and duration of streamflows. Conducting these assessments requires long-term records of streamflow for a diverse set of locations and geospatial information about the local streams and watersheds. These assessments also require trained hydrologists equipped with appropriate software to conduct statistical studies, interpret the data, and provide the results in reports and interactive data bases.

Regional estimates of flow must be revised regularly because additional data improve the accuracy of the estimates, and because flow characteristics change over time due to changes in climate, land use, water-management practices, and water-use patterns. For example, one of the more controversial questions in the climate change debate is whether changes in climate are causing changes in the magnitude and frequency of floods and droughts. Study of this crucial question has been limited and most analyses have been conducted on a State-by-State basis. (See recent examples of USGS streamflow information used to address these issues.). Stable Federal funding is needed to continually provide the requisite data and analyses on a broad regional scale to address these regional and national questions.

4. Data Delivery

An essential building block of the NSIP plan is to develop new ways to transmit, store, and distribute streamflow information. NSIP will provide convenient and reliable access to all of its information products through the World Wide Web. Access to and delivery of these products must be enhanced to keep pace with rapid technological advancements and customer expectations of having information when and where they need it.

One delivery aspect that was undertaken starting in FY 2001 is a national system of redundant web servers, called NATWEB, designed to ensure data delivery in times of high customer demand, heavy internet traffic, or local failures in power or communications systems. The increasing number of streamgages delivering information in real time heightens customer expectations for data to be available 7 days a week, 24 hours a day. During a recent hurricane, a USGS computer system failure interrupted the flow of information to users in the region where the hurricane was causing severe flooding, even though the streamgages and their satellite telemetry were still working. NATWEB provides "mirror sites" so that the data from any given streamgage can be served by several computers located in different regions of the Nation. This redundancy has greatly enhanced the reliability of data delivery.

A second important enhancement in data delivery is a web-based system for providing the entire storehouse of USGS hydrologic data to the public. The system, called NWIS-Web was first deployed in the Fall of 2000, and delivers historical and current streamflow data in a variety of formats and graphical presentations. One of the customer benefits is the flexibility to create varied forms of output.

A further enhancement will be the delivery of the vast store of streamflow data that have been collected at frequent (usually 15-minute) intervals. These frequently collected data (called "unit values") are invaluable to many types of hydrologic analysis, including calibration of flood-forecasting models, analysis of flood-mitigation strategies, and water-quality studies for Total Maximum Daily Loads (TMDLs), which are used for compliance with water-quality standards. The data warehouse makes it possible for these requests to be filled in minutes by the user, with minimal impact on the USGS. The USGS Instantaneous Data Archive (IDA) is currently being populated with unit value data and already has over 1 billion values.

Finally, the NSIP plan calls for new web-based applications that will allow the user to select any location on any stream and use GIS interfaces and existing statistical models to compute streamflow charactersitics. The system will substantially reduce the time required by engineers and resource manage-ment agencies to make determinations of flow statistics required for regulatory activities, such as permit processing, flood-plain delineation, or TMDL applications. The first prototype of such a system has been developed by the USGS ( and serves as an example of the kind of information delivery system that NSIP would provide.

5. Investing in Methods Development and Research

Although there have been great advances in methods for measuring water levels, computing streamflow, and storing and transmitting data, the methods for measuring flow at most streamgages are almost identical to those of 100 years ago. At a growing number of streamgages, however, the use of acoustic Doppler technology is dramatically changing the way flow is measured. These acoustic methods enhance the range of conditions for which accurate flow measurements are possible, but they do not provide enhanced efficiency or accuracy at most locations. No new technology has yet been found to provide accurate data over a wide range of hydrologic conditions more cost-effectively than traditional current-meter methods. Prudent management, however, requires that the USGS continue efforts to explore and test new technologies for streamgaging that have the potential to enhance operational safety, reduce cost, improve accuracy, and (or) increase reliability of flow data. The USGS is collaborating with university and private-sector partners in a search for new approaches to streamgaging. Early tests of various new radar systems show promise, but much more testing and development are needed before major improvements in technology can be realized.

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