Commissioned by the municipality, Antea Group measured the salinity of the Harlingen canals in Friesland. They did that by traveling the length of the canals. Attached to a motorboat, there was an advanced mobile multiparameter probe. They used this to conduct the measurements.
The municipality of Harlingen was curious to know the salt content of the water in the canals and harbor, and where the salt came from. This is important, because the salt content in surface water is a determining factor for the rate of silt deposition. The faster silt builds up, the more often a canal or harbour has to be dredged. In other words: the presence and amount of salt in the surface water has a direct impact on the maintenance costs for the canals and harbor.
'We did two rounds of measurements with a measuring boat for this project, at high and low tide', says project leader Jeroen Kruse. 'We did this, because we wanted to know whether the tide also affected the amount of salt in the water.'
The boat was equipped with a water quality probe that stored the values every half minute. 'We then imported the data in GIS and used it to generate a comprehensive chart showing the amounts of salt in the water.’
'There's a canal called Zoutsloot, which is Dutch for “salt canal”, where, perhaps unsurprisingly, the salt levels were very high indeed. As it turned out, the gate valve at the end of this watercourse was leaking. As a result of our measurements, the municipality of Harlingen replaced this gate valve. Later we conducted another round of measurements. The results, in fact, showed that the surface water salt content was significantly lower.'
Now that we have this measuring equipment, the door has been opened to carry out more projects of this kind.
'The use of the advanced water quality probe has proved to be a huge boon. It's much faster than taking samples, sending them to the lab, and receiving the results a few weeks later. This way it is much less expensive, and it is easier too.'
'We feel that now that we have this measuring equipment the door is open for doing more projects of this kind – perhaps with our new underwater drone. We've adapted it so the measuring equipment can be attached to it too, making it possible to measure at various depths. It's a great instrument that offers a new sea of possibilities!'
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