Besides the plant pallets on the raised platform, we also install a row of soil cores at the back of the flume each week. To do so, the FZK team especially designed and built the steel ‘flower pots’ that take the cores and expose their vertical side to the approaching waves. To save us time during flume filling every morning, we drain the water only to a height just below the cores. Given the water temperatures above 20 degrees and air tempereratures even higher, nobody minds this high water level when checking on the cores.
We use the cores to look at the effect of storm wave attack on exposed vertical sections of sediment representing marsh cliffs. Each week we install six 40cm deep cores with faces exposed to the waves. The cores are from two sites in the UK with contrasting sedimentology – one is sandy, while the other is finer and more cohesive. The cores, extracted as part of the NERC funded RESIST-UK project, have been scanned using a micro-CT scanner so that we can look at their internal structure: lamination, pore spaces, root networks and so forth. We hope that we will then be able to map the erosion that we observe under storm conditions to specific structural characteristics within the sediment. Given that the area where erosion may take place on these cores is vertical, the SET tables cannot be applied. But the SFM method applies here just as well and will give us detailed information how the cores responded to the wave conditions.
During the coming years of RESIST-UK we will also tie these characteristics to the surface vegetation and sediment characteristics that we can map from drones in the field. We will thereby build a link between features that we can see from the air and the vulnerability of the underlying sediments to storm waves, allowing us to make spatial predictions of marsh edge stability that complement the findings for the marsh surfaces that come from the rest of the experiment.