Eelke Folmer, Ecospace Lemmer: The intertidal coastal zone of the Wadden Sea consists of saltmarshes and adjacent mudflats. The coastal zone is important because of its natural values and because it protects the land against flooding. However, it is threatened by accelerating sea level rise. Knowledge about sedimentation, erosion and the interaction with vegetation is central to gain a better understanding of the growth capacity of the saltmarshes and mudflats.
RPAS (drone) based mapping combined with Structure-from-Motion photogrammetry offers possibilities to construct accurate, high-resolution maps and 3D models. During 2019/2020, we collaborated with Bas Borsje from the University of Twente, Blik van Boven and ATMOS UAV and carried out a pilot project to gain experience mapping intertidal coastal zones. We used the highly wind resistant and accurate Atmos Marlyn which allowed us to map more than 300-400 ha in 2-3 hours.
Mapping was done before and after winter which allowed us to assess changes in elevation. We constructed maps and 3D models and visualized sedimentation and erosion that took place during the winter storms. Thanks to the high-accuracy GNSS-PPK technology on the Marlyn, we were able to detect changes in elevation that were in the order of cm.
Our analyses show erosion on the outer mudflats and sedimentation within the brushwood groin fields. This information helps us to better understand the response and adaptive capacity of these intertidal systems to sea level rise and changing climate and helps to develop nature-based coastal protection solutions.