Online Stream Gauging Station

Automated flow measurement system in watercourses.

Measure flow and levels of channels and rivers

Stream gauging is the process of measuring the water flow at a particular point on a stream, river or canal. An online stream gauging station is an essential real-time tool for watercourse knowledge of said streams, rivers and canals.

The calculation of flow, based on the measurement of indirect or direct parameters, allows authorities to monitor watercourses across a country or region. A stream gauging station’s data series can also be used historically, for hydrological and hydraulic studies and modelling.

Autoimatic metric station

Indirect measuring technique

Invasive or non-invasive techniques can take water level measurements.

The most common invasive technique used is a measurement by float and counterweight in a tranquiliser well with a piezoresistive sensor.

Popular non-invasive techniques include ultrasonic or microwave RADAR technology or limnimetric scale digitalisation by image processing.

Flow rate is calculated by measuring the water level and the flow rate curve (q-h), based on the hydrological modelling of the natural or artificial section, or empirically if it is a prefabricated section.

Calibrating the flow rate curve through direct measurements maintains the reliability of indirect flow measurements.

Direct measuring technique

In natural sections of rivers and canals, indirect measurements can cause a high uncertainty in results. The measurement of the flow velocity-directly related to the resulting flow through the geometric model of the riverbed-is used instead.

Direct measuring techniques are also invasive or non-invasive.

Ultrasonic measurement is an invasive technique. For natural streams or open channels, Doppler profilers measure water current velocities or transit time measurements can be taken to establish flows.

Non-invasive direct flow measurements involve the measurement of surface speed. Flow can be gauged using radar or computer vision, or a combination of both techniques.


  • Fundamental part of river and irrigation canal management.
  • Hydrological information systems provide knowledge about river basins.
  • Flood forecasting, resource management and control of inputs and outputs in reservoirs.
  • Modelling of rivers, channels and basins.
  • Fundamental element to quantify circulating water resources.
  • Direct and indirect measuring techniques.

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