The End of the Marie-Curie Postdoc-Project «SmartWood_3D» is approaching
Innovative smart-sensors and Structure-from-Motion photogrammetry allow for novel insights into transport and depositional processes of wood in rivers. In the course of the SmartWood_3D project, these two methods were further developed and applied, for the very first time, at field scale to quantify large wood (LW) dynamics (rolling, rotation, impacts) and to assess LW accumulation characteristics (volume, porosity, structural alignment). The gained data are currently being analysed.
Ten custom designed smart sensor units were purchased and installed into 4 m long prototype wood logs with a mean diameter of 0.33 m, so called SmartWood. During the floods in summer 2021, SmartWood experiments were carried out for the first time at field-scale, considering three Swiss rivers; the Grosse Melchaa River in the canton of Obwalden, as well as the Thur and Limmat River in the canton of Zurich (Figure 1). The sensors and SmartWood-logs met the requirements for field-scale experiments, while novel data about LW dynamics could be collected. These data are currently processed and analysed.
The gained sensor data will allow for the assessment of LW orientation and transport velocity from inertial measurements (acceleration, angular velocity, magnetic flux). In addition, they also show great potential for the reconstruction of 3D transport trajectories (from IMU and GPS data). Furthermore, SmartWood data provide new insights into LW impact forces, arising from collisions with in-stream structures and channel boundaries.
Besides focusing on LW movement dynamics in Swiss rivers, characteristics (e.g., volume, porosity, structural alignment) of prototype LW accumulations were assessed in the field (Figure 2). Intact LW accumulations all across Switzerland were mapped via close-range aerial Structure-from-Motion photogrammetry, yielding 3D replicates (digital twin models) of the examined wooden deposit and thus allowing precise volumetric measurements (2.5D and 3D volume). Afterwards, the deposits were removed from the stream system and thoroughly quantified (weighed, processing to wood chips), while wooden samples were brought to the laboratory for detailed analysis (wet density, dry density, water content). Based on the obtained data and parameter, the net wood volume (solid cubic meter, solid wood volume) is estimated. The solid wood volume represents an important measure besides the 2.5D and 3D volume (bulk volumes) for porosity estimates. Currently, an efficient workflow-pipeline is elaborated, which will enable the rapid assessment of prototype LW accumulations using digital twin models.
Data gained in the course of the SmartWood_3D project are of relevance for river managers and engineers to maintain existing as well as design new in-stream infrastructure. Furthermore, the generated data provide invaluable information about transport and depositional dynamics which are required for the calibration and verification in numerical modelling.
We appreciate the support received from power plant operators (EKZ, EWO, KHR, Axpo, Ofible), the local community Sarnen, the Building Department of the Canton of Zurich as well as the Swiss Federal Office for the Environment (BAFU) and every single person involved.
Conferences and Publications:
- Gabriel Spreitzer, Isabella Schalko, Robert M. Boes & Volker Weitbrecht, 2021. Video footage from drones for Structure-from-Motion photogrammetry-A practical and rapid assessment method for large wood accumulations in rivers? EGU General Assembly 2021. Vienna, Austria. DOI: external page 10.5194/egusphere-egu21-4966
- Gabriel Spreitzer, Isabella Schalko, Robert M. Boes & Volker Weitbrecht, 2021. Innovative Sensors for Measuring Large Wood (LW) Movement Dynamics in Rivers. AGU Fall Meeting 2021. New Orleans, United States. DOI: external page https://ui.adsabs.harvard.edu/abs/2021AGUFMEP55B1114S/abstract
- Gabriel Spreitzer, Isabella Schalko, Robert M. Boes & Volker Weitbrecht, 2022. Quantification of large wood (LW) impact forces at field-scale using SmartWood, Proceedings of the 39th IAHR World Congress. Granada, Spain. DOI: in preparation.