Report on the study and comparative measurements carried out by ASICON  for the account of the Flemish Ministry - Department of Waterways Management - Hydrological Research Lab of Borgerhout.     

ACCURATE MEASUREMENTS

The purpose of the study was to evaluate if an acoustic Doppler current meter could be used as reliable alternative to acoustic flow meters (AFM) with 8 transducer heads measuring in dual cross configuration.

This "classic" transducers setup in canals and waterways has the disadvantage to require cables running to each transducer, what is implying quite an infrastructure.

Thanks to the setup of only one single acoustic Doppler current meter , measuring with horizontal beams, a cost efficient and flexible alternative is now possible! 

THE EQUIPMENT SETUP

The measurements were carried out on the River De Leie, located in SW of Belgium, near Kortrijk, and in the immediate vicinity of the border between Belgium and France.

The river has been canalised in this area and is approx. 33m (100 ft) wide. There is a fixed measuring station with AFM's operating in dual cross mode.

Mounted just next to the AFM's, the acoustic Doppler current meter  measured during 33 days in the period december 2000 / january 2001.

The  Doppler-transducer measures the current by using doppler shift with two ultrasonic bundles on a frequency of  500 kHz in a pre-programmable range of cells.

The acoustic Doppler current meter  was operating completely as "stand-alone" sensor, powered by internal batteries and logging data in it's internal memory.

The graph hereabove shows the results of discharge through the acoustic Doppler current meter  (green curve) next to those measured with the acoustic flow meter (blue curve).

The acoustic Doppler current meter  functioned  perfecty during the complete measurement campaign and gave minimal deviations of discharge rates - less than 1.7% -  as compared to the fixed AFM sensor system, even under strongly fluctuating discharge levels.

With this study is was demonstrated that the acoustic Doppler current meter technology is to be considered as a valid and accurate alternative to acoustic flow meters, for permanent or temporary measurements in the field.

For further details regarding this study and the results, feel free to contacts us.

For all current and discharge measurements in canals, waterways and small rivers, ASICON recommends the range of RD Instruments sensors .

 

The LISST-25 is an advanced turbidity probe operating on basis of the "forward laser scattering" principle, a unique and patented method developed by SEQUOIA SCIENTIFIC which produces outstanding results.

The compact sensor was set up for this test as a "stand alone" probe, powered by internal batteries and with data registration on it's internal memory.

The probe is available in different versions, and according to the optical path length, different ranges are possible.

The advanced probe developed by SEQUOIA SCIENTIFIC provides accurate and reliable results, which can't  be obtained by any other sensor available on the market.

The results - if necessary calibrated in accordance with the prevailing typical environmental conditions - are easily processed and analysed after transfer to a PC.

The various parameters of operation during measurement are preset through a "bach" file which configures the sensor.

During measurements, a LED-light blinks as convenient external  indication of operation and sampling activities.

The probe is powered by ordinary 9v "block" type batteries available at any retail store.

See the results of measurements during a period of 50 min below - the peaks are produced by vessels passing-by on the canal and the corresponding agitation by the wake.