A New Evaluation of the USGS Streamgaging Network--A Report to Congress
The streamgaging network is part way through a transformation, from a
system designed for long-term use to one designed for a combination of
long-term and reliable real-time use.|
In addition to the network evaluation described above, we have been examining and making investments in operational modernization of the stations and information delivery systems. These systems must be upgraded to accommodate new uses of the information and to take advantage of new technological capabilities.
The purposes of the streamgaging network have expanded significantly over its lifetime. The network infrastructure that exists today was largely funded and built to satisfy resource assessment, design and long-term planning goals. Capabilities to satisfy real-time data uses have been added in recent years, and yet additional investments are needed to allow the existing network to achieve the level of usefulness and reliability that is technically feasible today. These include floodproofing of stations, extending streamflow ratings, adding raingages to streamgaging stations, adding backup systems for data transmission, and research and development for enhanced streamgaging capabilities.
By their very nature, streamgaging stations are vulnerable to flood damages. They must be constructed near the river and shelters and instruments can be inundated, damaged or destroyed by flood-waters and flood-born debris. These risks can be minimized by incurring additional costs to make the structures taller (place critical electronic or mechanical components above potential high water), use stronger construction materials, or build the stations farther from the river channel and run longer connections to the river.
Delivering of current streamflow data to end users consists of many steps, each of which has some risk of failure. Achieving the full benefit of these current uses depends on having a high level of system reliability. One way to improve reliability is to provide backup systems for data transmission and dissemination to end users.
The streamgaging network is part way through a transformation, from a system designed for long-term use to one designed for a combination of long-term and reliable real-time use. For the past several years this transition has been funded by increasing the unit cost of individual stations. The steps described here are costly and attempts to fund them more rapidly out of current operating funds could cause additional increases in station costs and would result in withdrawal of some funding support from other agencies and discontinuation of stations. The USGS has proposed plans to modernize the streamgaging network for real-time data processing. We will use these plans and a vigorous program of research and development to identify new technologies for transforming the network in a manner that does not cause further harm to Federal network goals.
The longstanding programs of the USGS to collect and publish basic
streamflow information provide very important information to a broad
community of water users and water management organizations. . . . .The
Commission received considerable comment about the need to maintain and
ensure the continuity in this basic data collection program. Steps should
be taken to develop among the agencies and cooperators a plan for this
program that results in greater financial and programmatic stability, and
this plan should be presented to the Congress for additional funding if
needed. [Western Water Policy Review Advisory Commission, June 1998]
We believe the U.S.G.S. basic water quantity data collection activities are essential, because the value of hydrologic data increases with both the length and continuity of the record; the logical responsibility of the Federal Government, . . . . cost-effective, because coordinated water data collection eliminates overlapping and duplicative efforts. These data are critical to a wide range of activities, . . . . How can engineers devise optimum responses, and design the most cost-effective facilities, if they have incomplete and inadequate hydrologic data? [comments by William J. Carroll, President-Elect of the American Society of Civil Engineers, to the Subcommittee on Interior and Related Agencies, March 10, 1988]
The USGS streamgaging network is a unique and irreplaceable source of
primary data supporting planning, research, and management for hydrologic
hazards. [Water Science and Technology Board, National Research Council,
Extending streamflow ratings to levels higher than have been directly observed at stations will provide an invaluable service to the NWS and other organizations that need time-critical streamflow data during floods. Theoretical ratings based on labor-intensive hydraulic surveys will provide real-time estimates of flood discharges for virtually any flood that could be anticipated at a streamgaging station.
Installing real-time rain gages at streamgaging stations with real-time telemetry is another cost-effective investment to support the Nation's flood forecasting capabilities. A major feature of the NWS modernization has been the deployment of 164 Doppler radar systems covering virtually the entire Nation. One weakness of the Doppler radar systems is that, although they do an excellent job of indicating the relative intensity of precipitation around a region, they are less successful at determining the actual quantity of rain. Additional real-time rainfall data would help them calibrate the radar data in each storm event, thus providing more accurate spatial distributions of rainfall to drive their flood-forecast models.
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U.S. Department of the Interior, U.S. Geological Survey