Neil Yobbi, U.S. Geological Survey hydrologic technician, uses an Acoustic Doppler Velocimeter to measure stream flow on Curlew Creek in Tampa, Florida. While Hurricane Hermine might have made landfall almost 200 miles away in St.
How is a rating curve used to convert gage height into streamflow?
In order to convert gage height (or "stage", usually expressed as feet) into streamflow (or "discharge", usually expressed as cubic feet per second), USGS hydrographers must establish a relationship between them. This stage-discharge relationship is called a rating curve. It’s developed by making frequent manual discrete discharge measurements at stream gaging stations.
The rating curve depends on the physical characteristics of the stream channel and floodplain, and will vary over time at almost every station. There are often subtle changes to a natural stream channel, such as the growth of aquatic vegetation in the summer, frequent shifting of a sand-bed stream bottom, catastrophic changes due to floods, or man-made changes such as construction of a bridge. These changes might require only minor or temporary adjustments to the rating curve, or they could require the development of a new one.
Provisional rating curves for many USGS streamgages are posted in WaterWatch. Place your cursor over the site of interest and left-click. That generates a pop-up window with a rating tab on the far right. Or if you know the site number for a USGS streamgage, plug it into the Customized Rating Curve Builder. For more information about site-specific rating curves, contact the USGS Water Science Center that manages the site.
Learn more:
Related Content
Is there a way to get alerts about streamflow conditions?
Yes! The U.S. Geological Survey WaterAlert service provides notifications to your email or phone for changes in water conditions based on thresholds you choose.
What does the term "stream stage" mean?
Stream stage is an important concept when analyzing how much water is moving in a stream at any given moment. "Stage" is the water level above some arbitrary point in the river and is commonly measured in feet. For example, on a normal day when no rain has fallen for a while, a river might have a stage of 2 feet. If a big storm hits, the river stage could rise to 15 or 20 feet, sometimes very...
Does "stage" tell you how much water is flowing in a stream?
Not directly. You cannot say that because a stream rises (doubles) from a 10-foot stage to a 20-foot stage that the amount of flowing water also doubles. Think of a cereal bowl with a rounded bottom. Pour one inch of milk in it. It doesn't take much milk to make it up to the one inch level because the bowl is at its narrowest near the bottom. Now, pour in milk until it is two inches deep -- it...
Why are there sometimes differences between USGS and National Weather Service river stages?
At some USGS streamgage installations, NOAA’s National Weather Service (NWS) maintains a separate stage sensor that is serviced by NWS technicians. Calibration of any sensing device can occasionally drift from a "true" value, so there might be differences between USGS and NWS data reports. USGS personnel visit installations on an interval of 6 weeks or less to maintain equipment and make required...
Sometimes the USGS real-time stage data seems too high (or too low). Are the USGS data inaccurate?
There can be occasional equipment or database problems where erroneous data are reported for short periods of time until corrections can be made. This is why it is important to look at a record of streamflow (like the 7-day hydrograph plots) rather than a single point in time. However, most of the time the USGS has a high level of confidence in its real-time stage data. During low streamflow...
Where can I get real-time and historical streamflow information?
The best starting point for USGS streamflow data is the interactive National Water Information System (NWIS): Mapper website. Zoom in to your area of interest or use the search options in the left navigation window. The map displays active surface-water sites by default, but you can change the type of water site (surface-water, groundwater, springs, atmospheric) and select to show inactive sites...
Why does the USGS use the spelling "gage" instead of "gauge"?
The spelling of “gage” is part of our very rich USGS history. We have used that spelling for over a hundred years. In 1888, USGS Director John Wesley Powell met a very forward-thinking graduate student named Frederick Haynes Newell. Powell was so impressed that he made Newell the first full-time appointee to the new Irrigation Survey, which was created to investigate the potential for dams and...
Why might USGS streamflow data be revised?
Real-time USGS streamflow data are PROVISIONAL, meaning that the data have not been reviewed or edited. These data might be subject to significant change and are not official until reviewed and approved by the USGS. Real-time streamflow data can be affected by: backwater from ice or debris such as log jams algae and aquatic growth in the stream sediment movement malfunction of recording equipment...
Neil Yobbi, U.S. Geological Survey hydrologic technician, uses an Acoustic Doppler Velocimeter to measure stream flow on Curlew Creek in Tampa, Florida. While Hurricane Hermine might have made landfall almost 200 miles away in St.
On April 29, hydrologic technicians Anthony Underwood and Jeremiah Pomerleau visited the USGS gaging station on the St. John River at Ninemile Bridge and found a sea of broken up, dirty ice left behind by a recent ice jam.
According to Anthony, photos don't do the size and scale of the ice chunks any justice.
On April 29, hydrologic technicians Anthony Underwood and Jeremiah Pomerleau visited the USGS gaging station on the St. John River at Ninemile Bridge and found a sea of broken up, dirty ice left behind by a recent ice jam.
According to Anthony, photos don't do the size and scale of the ice chunks any justice.
On February 26, Nick Stasulis and Charlie Culbertson visited USGS station 01054200 Wild River at Gilead, Maine to make a streamflow measurement through the ice. For these measurements, 20-30 holes are drilled through the ice and a current meter (the spinning yellow cups) is used to measure velocity. River depths and distance across the channel are also measured.
On February 26, Nick Stasulis and Charlie Culbertson visited USGS station 01054200 Wild River at Gilead, Maine to make a streamflow measurement through the ice. For these measurements, 20-30 holes are drilled through the ice and a current meter (the spinning yellow cups) is used to measure velocity. River depths and distance across the channel are also measured.
This time-lapse photo shows the process that U.S. Geological Survey hydrographers use to measure streamflow across the cross-section of a wadeable river. USGS hydrographers follow standard, documented techniques and methods to ensure high-qualtiy, reliable data.
This time-lapse photo shows the process that U.S. Geological Survey hydrographers use to measure streamflow across the cross-section of a wadeable river. USGS hydrographers follow standard, documented techniques and methods to ensure high-qualtiy, reliable data.
USGS employee, Hanna Coy, talks about stream gauging.
USGS employee, Hanna Coy, talks about stream gauging.
USGS employees talk about the importance of getting accurate data from stream gauging and the benefit of the stage discharge ratings class.
USGS employees talk about the importance of getting accurate data from stream gauging and the benefit of the stage discharge ratings class.
USGS scientists John Miller and Brent Hall measure the streamflow and water levels at the flooded Ditch 14 near Mapleton, ND. What appears to be a lake is actually a flooded cornfield.
USGS scientists John Miller and Brent Hall measure the streamflow and water levels at the flooded Ditch 14 near Mapleton, ND. What appears to be a lake is actually a flooded cornfield.
USGS hydrologic technician measuring streamflow in the Merced River, near Happy Isles stream gage in Yosemite Valley.
USGS hydrologic technician measuring streamflow in the Merced River, near Happy Isles stream gage in Yosemite Valley.
Whether you drink water from your tap, use electricity or canoe down your local river, chances are you benefit from USGS streamgage information. So what is a streamgage and what does it do for you? This CoreCast episode gives you the inside scoop on your silent superhero.
Transcript and captions available soon.
Whether you drink water from your tap, use electricity or canoe down your local river, chances are you benefit from USGS streamgage information. So what is a streamgage and what does it do for you? This CoreCast episode gives you the inside scoop on your silent superhero.
Transcript and captions available soon.
Compilation of streamflow statistics calculated from daily mean streamflow data collected during water years 1901–2015 for selected U.S. Geological Survey streamgages
River rating complexity
How does a U.S. Geological Survey streamgage work?
Discharge measurements at gaging stations
From the River to You: USGS Real-Time Streamflow Information...from the National Streamflow Information Program
Stage-discharge relations -- basic concepts
Standards for the Analysis and Processing of Surface-Water Data and Information Using Electronic Methods
The stream-gaging program of the U.S. Geological Survey
Related Content
- FAQ
Is there a way to get alerts about streamflow conditions?
Yes! The U.S. Geological Survey WaterAlert service provides notifications to your email or phone for changes in water conditions based on thresholds you choose.
What does the term "stream stage" mean?
Stream stage is an important concept when analyzing how much water is moving in a stream at any given moment. "Stage" is the water level above some arbitrary point in the river and is commonly measured in feet. For example, on a normal day when no rain has fallen for a while, a river might have a stage of 2 feet. If a big storm hits, the river stage could rise to 15 or 20 feet, sometimes very...
Does "stage" tell you how much water is flowing in a stream?
Not directly. You cannot say that because a stream rises (doubles) from a 10-foot stage to a 20-foot stage that the amount of flowing water also doubles. Think of a cereal bowl with a rounded bottom. Pour one inch of milk in it. It doesn't take much milk to make it up to the one inch level because the bowl is at its narrowest near the bottom. Now, pour in milk until it is two inches deep -- it...
Why are there sometimes differences between USGS and National Weather Service river stages?
At some USGS streamgage installations, NOAA’s National Weather Service (NWS) maintains a separate stage sensor that is serviced by NWS technicians. Calibration of any sensing device can occasionally drift from a "true" value, so there might be differences between USGS and NWS data reports. USGS personnel visit installations on an interval of 6 weeks or less to maintain equipment and make required...
Sometimes the USGS real-time stage data seems too high (or too low). Are the USGS data inaccurate?
There can be occasional equipment or database problems where erroneous data are reported for short periods of time until corrections can be made. This is why it is important to look at a record of streamflow (like the 7-day hydrograph plots) rather than a single point in time. However, most of the time the USGS has a high level of confidence in its real-time stage data. During low streamflow...
Where can I get real-time and historical streamflow information?
The best starting point for USGS streamflow data is the interactive National Water Information System (NWIS): Mapper website. Zoom in to your area of interest or use the search options in the left navigation window. The map displays active surface-water sites by default, but you can change the type of water site (surface-water, groundwater, springs, atmospheric) and select to show inactive sites...
Why does the USGS use the spelling "gage" instead of "gauge"?
The spelling of “gage” is part of our very rich USGS history. We have used that spelling for over a hundred years. In 1888, USGS Director John Wesley Powell met a very forward-thinking graduate student named Frederick Haynes Newell. Powell was so impressed that he made Newell the first full-time appointee to the new Irrigation Survey, which was created to investigate the potential for dams and...
Why might USGS streamflow data be revised?
Real-time USGS streamflow data are PROVISIONAL, meaning that the data have not been reviewed or edited. These data might be subject to significant change and are not official until reviewed and approved by the USGS. Real-time streamflow data can be affected by: backwater from ice or debris such as log jams algae and aquatic growth in the stream sediment movement malfunction of recording equipment...
- Multimedia
Measuring streamflow
Neil Yobbi, U.S. Geological Survey hydrologic technician, uses an Acoustic Doppler Velocimeter to measure stream flow on Curlew Creek in Tampa, Florida. While Hurricane Hermine might have made landfall almost 200 miles away in St.
Neil Yobbi, U.S. Geological Survey hydrologic technician, uses an Acoustic Doppler Velocimeter to measure stream flow on Curlew Creek in Tampa, Florida. While Hurricane Hermine might have made landfall almost 200 miles away in St.
Ice Jam RemnantsOn April 29, hydrologic technicians Anthony Underwood and Jeremiah Pomerleau visited the USGS gaging station on the St. John River at Ninemile Bridge and found a sea of broken up, dirty ice left behind by a recent ice jam.
According to Anthony, photos don't do the size and scale of the ice chunks any justice.
On April 29, hydrologic technicians Anthony Underwood and Jeremiah Pomerleau visited the USGS gaging station on the St. John River at Ninemile Bridge and found a sea of broken up, dirty ice left behind by a recent ice jam.
According to Anthony, photos don't do the size and scale of the ice chunks any justice.
Under The IceOn February 26, Nick Stasulis and Charlie Culbertson visited USGS station 01054200 Wild River at Gilead, Maine to make a streamflow measurement through the ice. For these measurements, 20-30 holes are drilled through the ice and a current meter (the spinning yellow cups) is used to measure velocity. River depths and distance across the channel are also measured.
On February 26, Nick Stasulis and Charlie Culbertson visited USGS station 01054200 Wild River at Gilead, Maine to make a streamflow measurement through the ice. For these measurements, 20-30 holes are drilled through the ice and a current meter (the spinning yellow cups) is used to measure velocity. River depths and distance across the channel are also measured.
Time-Lapse of Measuring StreamflowThis time-lapse photo shows the process that U.S. Geological Survey hydrographers use to measure streamflow across the cross-section of a wadeable river. USGS hydrographers follow standard, documented techniques and methods to ensure high-qualtiy, reliable data.
This time-lapse photo shows the process that U.S. Geological Survey hydrographers use to measure streamflow across the cross-section of a wadeable river. USGS hydrographers follow standard, documented techniques and methods to ensure high-qualtiy, reliable data.
Streamflow Gaging Station and Measurement on San Pedro River, AZStreamflow Gaging Station and Measurement on San Pedro River, AZStreamflow Gaging Station and Measurement on San Pedro River, AZUSGS employee, Hanna Coy, talks about stream gauging.
USGS employee, Hanna Coy, talks about stream gauging.
Stage Discharge Ratings ClassUSGS employees talk about the importance of getting accurate data from stream gauging and the benefit of the stage discharge ratings class.
USGS employees talk about the importance of getting accurate data from stream gauging and the benefit of the stage discharge ratings class.
Streamflow and Water Level MeasurementsUSGS scientists John Miller and Brent Hall measure the streamflow and water levels at the flooded Ditch 14 near Mapleton, ND. What appears to be a lake is actually a flooded cornfield.
USGS scientists John Miller and Brent Hall measure the streamflow and water levels at the flooded Ditch 14 near Mapleton, ND. What appears to be a lake is actually a flooded cornfield.
Measuring StreamflowUSGS hydrologic technician measuring streamflow in the Merced River, near Happy Isles stream gage in Yosemite Valley.
USGS hydrologic technician measuring streamflow in the Merced River, near Happy Isles stream gage in Yosemite Valley.
Streamgages: The Silent SuperheroWhether you drink water from your tap, use electricity or canoe down your local river, chances are you benefit from USGS streamgage information. So what is a streamgage and what does it do for you? This CoreCast episode gives you the inside scoop on your silent superhero.
Transcript and captions available soon.
Whether you drink water from your tap, use electricity or canoe down your local river, chances are you benefit from USGS streamgage information. So what is a streamgage and what does it do for you? This CoreCast episode gives you the inside scoop on your silent superhero.
Transcript and captions available soon.
- Publications
Compilation of streamflow statistics calculated from daily mean streamflow data collected during water years 1901–2015 for selected U.S. Geological Survey streamgages
Streamflow statistics are needed by decision makers for many planning, management, and design activities. The U.S. Geological Survey (USGS) StreamStats Web application provides convenient access to streamflow statistics for many streamgages by accessing the underlying StreamStatsDB database. In 2016, non-interpretive streamflow statistics were compiled for streamgages located throughout the NationAuthorsGregory E. Granato, Kernell G. Ries, Peter A. SteevesRiver rating complexity
Accuracy of streamflow data depends on the veracity of the rating model used to derive a continuous time series of discharge from the surrogate variables that can readily be collected autonomously at a streamgage. Ratings are typically represented as a simple monotonic increasing function (simple rating), meaning the discharge is a function of stage alone, however this is never truly the case unleAuthorsRobert R. HolmesHow does a U.S. Geological Survey streamgage work?
Information on the flow of rivers and streams is a vital national asset that safeguards lives, protects property, and ensures adequate water supplies for the future. The U.S. Geological Survey (USGS) operates a network of more than 9,000 streamgages nationwide with more than 500 in Texas.AuthorsDee L. LurryDischarge measurements at gaging stations
The techniques and standards for making discharge measurements at streamflow gaging stations are described in this publication. The vertical axis rotating-element current meter, principally the Price current meter, has been traditionally used for most measurements of discharge; however, advancements in acoustic technology have led to important developments in the use of acoustic Doppler current prAuthorsD. Phil Turnipseed, Vernon B. SauerFrom the River to You: USGS Real-Time Streamflow Information...from the National Streamflow Information Program
This Fact Sheet is one in a series that highlights information or recent research findings from the USGS National Streamflow Information Program (NSIP). The investigations and scientific results reported in this series require a nationally consistent streamgaging network with stable long-term monitoring sites and a rigorous program of data, quality assurance, management, archiving, and synthesis.AuthorsJoseph P. Nielsen, J. Michael NorrisStage-discharge relations -- basic concepts
No abstract available.AuthorsK. Michael Nolan, Larry Bohman, Tim Stamey, Gary FirdaStandards for the Analysis and Processing of Surface-Water Data and Information Using Electronic Methods
Surface-water computation methods and procedures are described in this report to provide standards from which a completely automated electronic processing system can be developed. To the greatest extent possible, the traditional U. S. Geological Survey (USGS) methodology and standards for streamflow data collection and analysis have been incorporated into these standards. Although USGS methodologyAuthorsVernon B. SauerThe stream-gaging program of the U.S. Geological Survey
The U.S. Geological Survey stream-gaging program provides streamflow data for a variety of purposes. The uses of streamflow data are described, and the growth of the stream-gaging program is related to legislation and the need to manage the Nation's water resources more effectively. A brief description is provided of the data-collection processes, computation of streamflow records, dissemination oAuthorsKenneth L. Wahl, Wilbert O. Thomas, Robert M. Hirsch - News