Automated direct measurement of streamflow discharge is difficult at present. In place of the direct measurement of streamflow discharge, one or more surrogate measurements can be used to produce discharge values. In the majority of cases, a stage (the elevation of the water surface) measurement is used as the surrogate. Low gradient (or shallow-sloped) streams are highly influenced by variable downstream channel conditions. For these streams, a second stream gauge would be installed, and the slope of the water surface would be calculated between the gauges. This value would be used along with the stage measurement to more accurately determine the streamflow discharge. Improvements in the accuracy of velocity sensors have also allowed the use of water velocity as a reliable surrogate for streamflow discharge at sites with a stable cross-sectional area. These sensors are permanently mounted in the stream and measure velocity at a particular location in the stream and related to flow in a manner similar to the use of traditional water level.
In those instances where only a stage measurement is used as the surrogate, a rating curve must be constructed. A rating curve is the functional relation between stage and discharge. It is determined by making repeated discrete measurements of streamflow discharge using a velocimeter and some means to measure the channel geometry to determine the cross-sectional area of the channel. The technicians and hydrologists responsible for determining the rating curve visit the site routinely, with special trips to measure the hydrologic extremes (floods and droughts), and make a discharge measurement by following an explicit set of instructions.
Once the rating curve is established, it can be used in conjunction with stage measurements to determine the volumetric streamflow discharge. This record then serves as an assessment of the volume of water that passes by the stream gauge and is useful for many tasks associated with hydrology.
In those instances where a velocity measurement is additionally used as a surrogate, an index velocity determination is conducted. This analysis uses a velocity sensor, often either magnetic or acoustic, to measure the velocity of the flow at a particular location in the stream cross section. Once again, discrete measurements of streamflow discharge are made by the technician or hydrologist at a variety of stages. For each discrete determination of streamflow discharge, the mean velocity of the cross section is determined by dividing streamflow discharge by the cross-sectional area. A rating curve, similar to that used for stage-discharge determinations, is constructed using the mean velocity and the index velocity from the permanently mounted meter. An additional rating curve is constructed that relates stage of the stream to cross-sectional area. Using these two ratings, the automatically collected stage produces an estimate of the cross-sectional area, and the automatically collected index velocity produces an estimate of the mean velocity of the cross section. The streamflow discharge is computed as the estimate of the cross section area and the estimate of the mean velocity of the streamflow.
A variety of hydraulic structures / primary device are used to improve the reliability of using water level as a surrogate for flow (improving the accuracy of the rating table), including:
Water pressure measuring device (Bubbler) - to measure water level via pressure (typically done directly in-stream without a stilling well)
Stage encoder - a potentiometer with a wheel and pulley system connected to a float in a stilling well to provide an electronic reading of the water level
Discharge measurements of a stream or canal without an established stream gauge can be made using a current meter or Acoustic Doppler current profiler. One informal methods that is not acceptable for any official or scientific purpose, but can be useful is the float method, in which a floating object such as a piece of wood or orange peel is observed floating down the stream.[1]
The first routine measurements of river flow in England began on the Thames and Lea in the 1880s,[2] and in Scotland on the River Garry in 1913.[3] The national gauging station network was established in its current form by the early 1970s and consists of approximately 1500 flow measurement stations supplemented by a variable number of temporary monitoring sites.[2] The Environment Agency is responsible for collection and analysis of hydrometric data in England, Natural Resources Wales in Wales, whilst responsibility for Scotland and Northern Ireland rests with the Scottish Environment Protection Agency and Rivers Agency respectively.[4]
In the United States, the U.S. Geological Survey (USGS) is the principal federal agency tasked with maintaining records of natural resources. Within the USGS, the Water Resources Division carries the responsibility for monitoring water resources.
To establish a stream gauge, USGS personnel first choose a site on a stream where the geometry is relatively stable and there is a suitable location to make discrete direct measurements of streamflow using specialized equipment. Many times this will be at a bridge or other stream crossing. Technicians then install equipment that measures the stage (the elevation of the water surface) or, more rarely, the velocity of the flow. Additional equipment is installed to record and transmit these readings (via the Geostationary Operational Environmental Satellite) to the Water Science Center office where the records are kept. The USGS has a Water Science Center office in every state within the United States. Current streamflow data from USGS streamgages may be viewed in map form at: [2].
Zimbabwe
In Zimbabwe, the national stream gauge network is the responsibility of the Zimbabwe National Water Authority. This is an extensive network covering all major rivers and catchments in the country. However, a review of existing gauges raised serious concerns about the reliability of the data of a minority of stations, due in part to ongoing funding problems.[5]
Bangladesh
The largest stream gauge network in Bangladesh is maintained by Bangladesh Water Development Board (BWDB). At few other locations, Bangladesh Inland Water Transport Authority maintains a few gauges to provide advisories for navigational purposes.[citation needed]
In the Czech Republic, in some measuring places (profiles) are defined three levels which define three degrees of flood-emergency activity. The degree I is a situation of alertness, the degree II is a situation of readiness, the degree III is a situation of danger.
Canada
Canadian streams and rivers are monitored by the Water Survey of Canada, a branch of Environment and Climate Change Canada. As of 2021, it operates or collects data from more than 2800 gauges across Canada.[6] This data is used by provincial and territory governments to inform flood predictions and water management.
Sri lanka
In sri lanka stream and rivers are monitored by Hydrology and Disaster Management Division a branch of Irrigation Department.it operated nearly 40 gauging station around the island.
Tide gauge – Device for measuring the change in sea level relative to a datum
Water column – Conceptual column of water from the surface to the bottom of a body of water
Water level – Elevation of the free surface of a stream, lake or reservoir relative to a specified vertical datum
Nilometer – Structure for measuring the Nile River's clarity and water level
References
^Harrelson, Cheryl C; Rawlins, C. L.; Potyondy, John P. (1994). "Stream channel reference sites: an illustrated guide to field technique. Gen. Tech. Rep. RM-24" (PDF). U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. Retrieved 2011-01-13.
^ ab"The UK Gauging Station Network". Hydrometry in the UK. Centre of Ecology and Hydrology. Retrieved 29 March 2011.
^"A brief history of river level monitoring in Scotland". Scottish Environment Protection Agency. Retrieved 29 March 2011.
^"Measuring Authorities". Hydrometry in the UK. Centre of Ecology and Hydrology. Retrieved 29 March 2011.
^Nyabeze, W.R. 2005. Calibrating a distributed model to estimate runoff for ungauged catchments in Zimbabwe. Physics and Chemistry of the Earth, 30, 625-633. [1]
^Canada, Environment and Climate Change (2007-01-09). "Water Survey of Canada". www.canada.ca. Retrieved 2021-06-26.
Further reading
World Meteorological Organization (2010) Manual on Stream Gauging.
Wikimedia Commons has media related to Stream gauge.
Contoocook River Streamflow-Gaging Station, Water Resources of New Hampshire and Vermont
"USGS Surface-Water Data for the Nation"
UK Hydrometric Register (pdf) A catalogue of river flow gauging stations and observation wells and boreholes in the United Kingdom together with summary hydrometric and spatial statistics.
"Radio Gauge Warns of Flood as Water Rises" Popular Mechanics, July 1935
January 26, 2023
stream, gauge, canal, boat, gauging, indexing, station, toll, point, gauging, point, stream, gauge, streamgage, stream, gauging, station, location, used, hydrologists, environmental, scientists, monitor, test, terrestrial, bodies, water, hydrometric, measureme. For the canal boat gauging or indexing station see Toll point Gauging point 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 volumetric discharge flow are generally taken and observations of biota and water quality may also be made The locations of gauging stations are often found on topographical maps Some gauging stations are highly automated and may include telemetry capability transmitted to a central data logging facility Brant Broughton Gauging Station on the River Brant in Lincolnshire England Contents 1 Measurement equipment 2 National stream gauge networks 2 1 United Kingdom 2 2 United States 2 3 Zimbabwe 2 4 Bangladesh 2 5 Czech Republic 2 6 Canada 2 7 Sri lanka 3 See also 4 References 5 Further reading 6 External linksMeasurement equipment EditSee also Streamflow Measurement Stream Gaging Station Carnation Washington Automated direct measurement of streamflow discharge is difficult at present In place of the direct measurement of streamflow discharge one or more surrogate measurements can be used to produce discharge values In the majority of cases a stage the elevation of the water surface measurement is used as the surrogate Low gradient or shallow sloped streams are highly influenced by variable downstream channel conditions For these streams a second stream gauge would be installed and the slope of the water surface would be calculated between the gauges This value would be used along with the stage measurement to more accurately determine the streamflow discharge Improvements in the accuracy of velocity sensors have also allowed the use of water velocity as a reliable surrogate for streamflow discharge at sites with a stable cross sectional area These sensors are permanently mounted in the stream and measure velocity at a particular location in the stream and related to flow in a manner similar to the use of traditional water level In those instances where only a stage measurement is used as the surrogate a rating curve must be constructed A rating curve is the functional relation between stage and discharge It is determined by making repeated discrete measurements of streamflow discharge using a velocimeter and some means to measure the channel geometry to determine the cross sectional area of the channel The technicians and hydrologists responsible for determining the rating curve visit the site routinely with special trips to measure the hydrologic extremes floods and droughts and make a discharge measurement by following an explicit set of instructions December 12 2001 photo of the USGS streamflow gaging station at Huey Creek McMurdo Dry Valleys Antarctica Once the rating curve is established it can be used in conjunction with stage measurements to determine the volumetric streamflow discharge This record then serves as an assessment of the volume of water that passes by the stream gauge and is useful for many tasks associated with hydrology In those instances where a velocity measurement is additionally used as a surrogate an index velocity determination is conducted This analysis uses a velocity sensor often either magnetic or acoustic to measure the velocity of the flow at a particular location in the stream cross section Once again discrete measurements of streamflow discharge are made by the technician or hydrologist at a variety of stages For each discrete determination of streamflow discharge the mean velocity of the cross section is determined by dividing streamflow discharge by the cross sectional area A rating curve similar to that used for stage discharge determinations is constructed using the mean velocity and the index velocity from the permanently mounted meter An additional rating curve is constructed that relates stage of the stream to cross sectional area Using these two ratings the automatically collected stage produces an estimate of the cross sectional area and the automatically collected index velocity produces an estimate of the mean velocity of the cross section The streamflow discharge is computed as the estimate of the cross section area and the estimate of the mean velocity of the streamflow Stream gauge B62 a combination weir at Doddieburn on the Mzingwane River Zimbabwe A variety of hydraulic structures primary device are used to improve the reliability of using water level as a surrogate for flow improving the accuracy of the rating table including Weirs V notch broad crested sharp crested and combination weirs Flumes Parshall flumeOther equipment commonly used at permanent stream gauge include Cableways for suspending a hydrographer and current meter over a river to make high flow measurement Stilling well to provide a calm water level that can be measured by a sensorWater level gauges Staff head gauges for a visual indication of water depth Water pressure measuring device Bubbler to measure water level via pressure typically done directly in stream without a stilling well Stage encoder a potentiometer with a wheel and pulley system connected to a float in a stilling well to provide an electronic reading of the water level Simple ultrasonic devices to measure water level in a stilling well or directly in a canal Electromagnetic gaugesDischarge measurements of a stream or canal without an established stream gauge can be made using a current meter or Acoustic Doppler current profiler One informal methods that is not acceptable for any official or scientific purpose but can be useful is the float method in which a floating object such as a piece of wood or orange peel is observed floating down the stream 1 National stream gauge networks Edit Plaque marking the construction of the River Dove gauging station dedicated to Izaak Walton author of The Compleat Angler United Kingdom Edit The first routine measurements of river flow in England began on the Thames and Lea in the 1880s 2 and in Scotland on the River Garry in 1913 3 The national gauging station network was established in its current form by the early 1970s and consists of approximately 1500 flow measurement stations supplemented by a variable number of temporary monitoring sites 2 The Environment Agency is responsible for collection and analysis of hydrometric data in England Natural Resources Wales in Wales whilst responsibility for Scotland and Northern Ireland rests with the Scottish Environment Protection Agency and Rivers Agency respectively 4 United States Edit Hydrograph of the March 13 2007 Snoqualmie River flood In the United States the U S Geological Survey USGS is the principal federal agency tasked with maintaining records of natural resources Within the USGS the Water Resources Division carries the responsibility for monitoring water resources To establish a stream gauge USGS personnel first choose a site on a stream where the geometry is relatively stable and there is a suitable location to make discrete direct measurements of streamflow using specialized equipment Many times this will be at a bridge or other stream crossing Technicians then install equipment that measures the stage the elevation of the water surface or more rarely the velocity of the flow Additional equipment is installed to record and transmit these readings via the Geostationary Operational Environmental Satellite to the Water Science Center office where the records are kept The USGS has a Water Science Center office in every state within the United States Current streamflow data from USGS streamgages may be viewed in map form at 2 Zimbabwe Edit In Zimbabwe the national stream gauge network is the responsibility of the Zimbabwe National Water Authority This is an extensive network covering all major rivers and catchments in the country However a review of existing gauges raised serious concerns about the reliability of the data of a minority of stations due in part to ongoing funding problems 5 Bangladesh Edit The largest stream gauge network in Bangladesh is maintained by Bangladesh Water Development Board BWDB At few other locations Bangladesh Inland Water Transport Authority maintains a few gauges to provide advisories for navigational purposes citation needed Emergency levels I II and III at Ticha Orlice river in Chocen Czech Republic Czech Republic Edit In the Czech Republic in some measuring places profiles are defined three levels which define three degrees of flood emergency activity The degree I is a situation of alertness the degree II is a situation of readiness the degree III is a situation of danger Canada Edit Canadian streams and rivers are monitored by the Water Survey of Canada a branch of Environment and Climate Change Canada As of 2021 it operates or collects data from more than 2800 gauges across Canada 6 This data is used by provincial and territory governments to inform flood predictions and water management Sri lanka Edit In sri lanka stream and rivers are monitored by Hydrology and Disaster Management Division a branch of Irrigation Department it operated nearly 40 gauging station around the island See also EditEmbudo Stream Gauging Station Willow Beach Gauging Station Flood stage Hydrograph Hydrometry Monitoring the components of the hydrological cycle Hyetograph Hydrological model Hydrological transport model Tide gauge Device for measuring the change in sea level relative to a datum Water column Conceptual column of water from the surface to the bottom of a body of water Water level Elevation of the free surface of a stream lake or reservoir relative to a specified vertical datum Nilometer Structure for measuring the Nile River s clarity and water levelReferences Edit Harrelson Cheryl C Rawlins C L Potyondy John P 1994 Stream channel reference sites an illustrated guide to field technique Gen Tech Rep RM 24 PDF U S Department of Agriculture Forest Service Rocky Mountain Forest and Range Experiment Station Retrieved 2011 01 13 a b The UK Gauging Station Network Hydrometry in the UK Centre of Ecology and Hydrology Retrieved 29 March 2011 A brief history of river level monitoring in Scotland Scottish Environment Protection Agency Retrieved 29 March 2011 Measuring Authorities Hydrometry in the UK Centre of Ecology and Hydrology Retrieved 29 March 2011 Nyabeze W R 2005 Calibrating a distributed model to estimate runoff for ungauged catchments in Zimbabwe Physics and Chemistry of the Earth 30 625 633 1 Canada Environment and Climate Change 2007 01 09 Water Survey of Canada www canada ca Retrieved 2021 06 26 Further reading EditWorld Meteorological Organization 2010 Manual on Stream Gauging Volume I Fieldwork 3 Volume II Computation of Discharge 4 External links Edit Wikimedia Commons has media related to Stream gauge Contoocook River Streamflow Gaging Station Water Resources of New Hampshire and Vermont USGS Surface Water Data for the Nation UK Hydrometric Register pdf A catalogue of river flow gauging stations and observation wells and boreholes in the United Kingdom together with summary hydrometric and spatial statistics Radio Gauge Warns of Flood as Water Rises Popular Mechanics July 1935 Retrieved from https en wikipedia org w index php title Stream gauge amp oldid 1114719203, wikipedia, wiki, book, books, library,
