Sunday, September 28, 2014

Most surfzone instruments are in!

The first two weeks of the experiment are almost over, and most of the instruments in the surfzone are in position.Getting instruments installed in shallow waters can be tricky, so we are glad to have these up and running now.
Instrument Plan

Instruments in the surfzone are attached to pipes that are jetted with water into the sand.
Although we have witnessed this technique at other field experiments, it's new to us to organize it ourselves.
Luckily we have had amazing help by the visiting scientists, the lifeguards of 's Gravenzande (GVRB) and Shore captain Tycho.

In the beginning of the experiment we deployed the stations close to the beach with the pump on a elevated cart (see the 'progress day 3' message below).

Pump and jetpipes ready on the beach

Some stations are on the subtidal bar, which is just to deep for our cart to reach.
The lifeguards of 's Gravenzande helped out tremendoudly with these stations. We deployed all 6 ADCP stations on the subtidal bar with the pump on their boat and ourselves standing on the sandbar and jetting next to the boat.

Ronald ready to swim out one of the NPS ACDP's

The final stations of the array are in deeper water (4-5 meter) and cannot be deployed without divers. After a bad attempt earlier this week, these stations were finally deployed yesterday.
During these deployments we have experienced the strong longshore currents in this area. It is almost impossible to swim against the tidal current, and we we're glad to have the boat nearby.

So, all 11 ADCP's are in! We added some pressure sensor sensors in between the stations to get a better view on the wave properties and CTD's to see the interaction with the fresh water from the Rhine.
Tinkering with the instruments.

With all the poles in the water, we'll keep on checking the instruments in the coming weeks and replace the batteries from time to time.

First day of the experiment. The flags mark the sightline where the instruments of the main array have to be deployed

First little storm over the weekend (day 6 &7) with instrument stations A1 & A2 near the beach
Photo of the location of array A during the calm conditions of today.

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