Air temperature in the flume peaked just in time for the science team to arrive for the trial run. The last instruments to be installed in the flume arrived and responsibilities and task allocations were discussed. And then we dedicated a full day to trialling the installation of plant pallets in the flume, testing the frames that the FZK team had built to allow standardised photos of the plants after each run and perform sediment erosion measurements at defined points and time the different measurement techniques that we are planning to use. While it felt a bit odd to measure the leaning angle of an imaginary plant and taking photos of empty pallets, it was important to get a feel for how long each measurement takes.
Measurements on the plants and soil can only be performed once the flume is drained and for a flume the size of GWK this takes a while. And to be able to perform one test and finish the associated measurements within a day, we have to be as efficient as possible when it comes to taking the measurements. So based on the information how long individual measurements took, we then discussed the sequence of measurements and whether additional hands can speed up the process or not.
All these trials and discussions made for an intensive two days which was amplified by the ongoing heat wave. But by the time the team left again, we felt we had made good progress and can now make last minute adjustments to frames and methods in final preparation for the experiments.
The heat wave in Germany is in full swing with temperatures exceeding 35 degrees at times. Yet, the FZK team continues to puts concrete blocks and gravel in place to get everything ready in time for the experiments and the instruments are waiting patiently along the side of the flume to be installed, ready to be woken by the data acquisition system.
In the meantime, the housing for the various drag sensors were built in the workshop so they can safely be installed in a gap between the concrete blocks. These drag sensors are designed to measure the forces that act on them in a very high resolution. During our experiments, we will use these sensors to measure how forces on individual plants differ between summer and winter state of a salt marsh. For this comparison, identical pins are mounted on the sensors. These do not look like real plants, but it means that any differences we measure are caused by the surrounding plants and their state of health and are not influenced by the shape of the pins.
As the team at the wave flume is putting together the last remaining pieces of this awesome construction effort, the science team is preparing to converge on the flume facility in preparation of the first trial run… We want our carefully prepared tidal flat and marsh surfaces in tip-top condition right up to the point at which they will be brought into the flume for our first proper wave run, so we have to do this trial run without them.
To check that the equipment is fully working and that we all know what we are doing is extremely important, though – we cannot afford to take any risks after all this effort by so many people who have worked so hard to get us to this point. Thank you all and here’s to a successful trial run!
Final preparations underway in the large wave flume… our five ‘experimental zones’ are clearly visible across the 5m wide channel – imagine this all filled with water and giant storm waves rolling over the top….
Carefully inserting sampling tube…
While the South-East of the UK has experienced the driest June on record and in the middle of a heat wave, the RESIST team in the UK has been working hard… We are carefully excavating cores from a muddy east coast and a more sandy west coast marsh, before taking them to be scanned, allowing us to view their insides without disturbing so much as a single grain (well, not inside them, anyway)!
Beautiful iron deposits at depth – what causes these?
It’s hot and takes about 1.5 hours per core, but spirits are high, as we have time to discuss how marshes manage to build potentially impressive core stability…. Here’s hoping the sunshine lasts and ours is equally high as the UK core team spends several more hours working hard on the marsh…
Check out our linked NERC ‘RESIST (UK)’ project.
Labelling is key!
As core members of the Hydralab+ RESIST project we met for the first time in person at the FZK’s large wave flume facility (GWK) to discuss the challenge of preparing all of our 75(!) europallet-sized sediment and plant containers to be ready for the experimental runs in August this year. The challenge is enormous, but so is our enthusiasm…
Especially Tjeerd was so fascinated by the flume, its dimensions and possibilities that he kept sneaking away from the meeting and we constantly wondered: Where is Tjeerd?
And on that basis, we believe that we can achieve what we set out to do: to detect the wave energy thresholds beyond which seedlings and mature plants are damaged and/or removed from the tidal flats upon which they have become established during less stressful times. Knowing those thresholds will allow the people who look after our coastal communities, properties, and ecosystems, to plan better for the future. And who knows, perhaps we will also be able to find out how we can support plants during their early life stages, e.g. through placing biodegradable protection on the tidal flat until the plants are strong enough to withstand the highest storm surge…
With the new fresh leaves arising on the trees and flowers blooming everywhere, spring is definitely in the air. This makes the perfect time to plant our tussocks into the sediment boxes outside.
The RESIST gardening team prepared the boxes and arranged the different tussock setups for the various plant species. Finally they put the irrigation system in place.
Now lets grow some marsh species!
A hard-boiled group of RESIST team members went out to the marshes this month to collect salt marsh sods that will build the foundation for the salt marsh patches we will expose to hydrodynamic forces in the flume. Frost does not allow to plant them into the pallet boxes directly, but this step will be completed as soon as possible. Until then they will sit safe and sound all over the glass house.
Once in the pallet boxes, the vegetation will root into the boxes’ soil and expand laterally, providing us with a range of growth stages from freshly developed apical shoots to well established root/rhizome systems.
Yes, we are planning another amazing experiment, to see how strong and stable tidal flat sediments and marsh vegetation really are… watch this space!!
Check out the beautiful documentary on ‘natural coastal protection’ produced by the German/French TV Channel ‘Arte’ and screened last Saturday 21st November. Well worth a look even if you do not understand the languages!:
… with an appropriately decorated mortar board – even the mice get a space on it!
Congratulations! Well deserved! And a big ‘thank you’ – Without Franziska, the marsh would never have made it to the flume!