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.

Drifter deployments

With part of the nearshore arrays in place, the time for GPS-tracked drifter measurements has come. Next week an extensive set of drifter deployments is planned to map the complex flow patterns at the tip (most seaward point) of the Sand Motor. Last Tuesday the Delft team performed trial deployments in order to get to know the system.

The tip of the Sand Motor is influenced by a complex mixture of strong tidal currents and wave-driven currents over a spatially highly variable bathymetry, making it quite different from the adjacent 'regular' beach. Furthermore, there might be tidal eddies forming as a result of flow separation on the northern side during flood and on the southern side during ebb currents.

The beach maintained by worms?

Tube building worms in the intertidal zone of the Sand Motor lagune.

With the wind blowing in your face and the waves roaring furiously, only few scientists observe the tiny engineers on the bottom of the sea, working hard to shape their surroundings. We find all kinds of benthic creatures at our coastline and their physical presence alone affects sediment transport. To what extent can they shape our coastal landscape? The Royal Netherlands Institute for Sea Research (NIOZ) is trying to find out. Today we started an experiment placing artificial beds of tube building worms at the Sand Motor. Over the days we will measure bed elevation under different environmental conditions.

Artificial bed of tube building worms deployed in the intertidal zone.

Aeolian transport kicks in

After a fairly quiet period we are finally having some aeolian action. The team from TUDelft is currently measuring wind speeds and are counting the amount of sediment which is transported by wind at several locations at the Zandmotor. The sediment is counted using laser sensors at three different heights above the sand bed. If a sediment particle crosses the laser beam it is counted and the total counts per seconds are a proxi for the intensity of the sediment transport. It is expected that the intensity of the sediment transport relates to the wind speed where more wind induces larger transports. Also, the moisture content of the sediment bed is important since wet sand is more difficult to transport. Anyway, exiting data are coming in !

Sediment counting laser sensors mounted at three different heights above the sediment bed. A total of 8 measuring stations are currently installed.

Progress Day 3

The last two days have been full on. We all try to use these quiet days to install our measuring stations on the sea floor and in the intertidal zone. Not having high waves is making life less complicated. We have mounted 6 stations with ADCP's (horizontal and vertical) in the subtidal zone so far. Tomorrow they will try to complete the intertidal zone. At the water line the Utrecht team has installed some of their pressure sensors in the same cross shore arrays.

The TUDelft team in action jetting the pipes with the jetpump in small waves.

The Utrecht team has also set up a large array of pressure sensors in one particular cross shore array. In this array there is a more elaborated frame with instrument for more detailed flow measurements and a bottom scanner.

The 'spider' like rig of the Utrecht team in the intertidal zone.

MEGAPEX underway after day 1

The experiment starts with almost no wind and no waves. Utrecht university has (partly) deployed their rigs in the intertidal zone and Delft is working to get their aeolian sensors in place. Researchers have settled in their temporary accommodation. Last but not least our cabin at the beach arrived exactly on schedule !! (Thanks Tim)


We are slowly warming up our instruments and looking forward to windy and rainy weather with big waves to collect some interesting data !

The ZIRFAEA from Rijkswaterstaat was also with us installing the offshore rigs and moorings.

Welcome to the official MEGAPEX blog.

Here you can track the progress of the researchers efforts to learn as much as they can from the processes and developments at the Sand Engine mega nourishment.

Background information on the research activities can be found on the NeMo (click Megapex) and Naturecoast websites.