Simple and accurate flow measurement of surface water bodies in accordance with ISO 748:2021

Water and environmental agencies carry out discharge measurements in accordance with ISO guidelines and ISO 748 outlines methods for determining the velocity and the cross-section area in open channels as well as procedures for calculating the discharge.

In the new 2021 edition of ISO 748, the NIVUS patented cross correlation technology is included within the accepted type of measurement devices under Acoustic echo correlation velocimeters (AECVs).

The NivuFlow Stick acoustic echo correlation velocimeter from NIVUS, not only meets the ISO requirements, but also ensures a professional and enjoyable user experience thanks to its ease of use.

The NivuFlow Stick multipoint-measurement, acoustic echo correlation velocimeter is capable of measuring the full flow velocity profile with velocities automatically measured from the bottom of the channel up to the water surface. This significantly improves measurement accuracy and means that discharge measurements can be completed in a shorter time where the meter does not have to be positioned at the different sampling depths.

The simultaneous measurement of up to 32 individual velocity ‘windows’ within each vertical section measurement provides the user with a full understanding of the velocity curve and greater information and understanding of how the average velocity is calculated within the vertical section.

The single measured velocities and flow velocity curve are shown directly on the unit display and with each individual measurement build up to show a full channel velocity profile for the whole of the measurement location. The water depth in each vertical is also measured by an integrated hydrostatic level measurement and means that the river bed profile is automatically determined and displayed during the gauging.

When the measurement of all of the verticals has been completed, the NivuFlow Stick automatically computes the total discharge in accordance with both the Mean-Section and Mid-Section methods. To conclude, a complete PDF measurement report is created by the device, including information about the cross sectional area, discharge in each section, average velocity and water depth in the verticals, as well as the graphic representation of the flow profile.


This article has been reposted from Nivus Press:

Simple and accurate flow measurement of surface water bodies in accordance with ISO 748:2021,” Nivus. [Online] Available:

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