Research

State-of-the-art hazard analysis for debris flow processes requires the use of complex numerical models, the further development of which must follow both the latest scientific findings and adaptation to the findings of engineering practice. The DebrisFrame project is developing the foundations for a debris flow modelling framework based on the digital simulation tools of the open avalanche simulation framework AvaFrame. The principles of the development environment are openness of source, user-friendliness, comprehensive documentation and recommendations regarding a practice-relevant parameterisation. The focus of the developments is primarily on operational applicability in Austria, while at the same time laying the foundations for the academic requirements of training and research. On the basis of AvaFrame, functions for special mudflow modules/tools will be created on a similar basis to AvaFrame. Data of debris flow events from selected event documentation and current monitoring stations are systematically processed and serve as reference events and benchmarks for model testing. DebrisFrame will serve as a basis for the further development of an operational debris flow model for engineering practice. The project represents a significant innovation in the field of debris flow simulation. The improved determination of process areas and occurring forces supports the determination of exposure and vulnerability in risk management.

This project includes the data evaluation of the first operational data from sensors developed in previous projects using UAV/UAS for the contactless and non-contact recording of snow data. This method enables interference-free measurement of temperature, humidity, pressure and movement on avalanche slopes. The sensors are deployed in a test field in open terrain using UAV/UAS. A sensor network consisting of several sensor measurement boxes is set up at specific test locations. Regular data acquisition is carried out via a mobile base station which is stationary or mobile on the UAV. Furthermore, a concept is being developed on how avalanche commissions can use the data to assess local avalanche slopes. In previous projects, we have already developed a measuring system for moisture and temperature measurements in inaccessible avalanche starting areas, particularly with regard to sliding snow avalanches. With the measuring system developed in the preliminary projects, we are starting the first operational season this year on real avalanche slopes relevant to ÖBB. The measurement results will be checked for their practical suitability, validated with reference measurements, the data scientifically analysed and a final report written. We are aiming for an SCI publication as a scientific publication.

Hydrographic survey of five scours in the riverbed of the river Wienfluss 1) Hydrographic survey a) Unmanned survey boat for use in very small waters The survey boat includes a semi-autonomous navigation unit with survey-grade satellite navigation unit (GNSS) with double antenna system for precise alignment of the survey boat. b) Multibeam echo sounder (MBES) Norbit iWBMS (minimum water depth under the transducer: 0.2 m) The MBES scans the bottom of the riverbed with 512 beams per ping. The possibility of swiveling the fan allows adjacent areas to be detected which cannot be navigated by boat due to the water depth, but in particular steeply rising bank areas (drop-offs) can be detected. c) Post-processing of the echo sounder measurement data The existing shallow water depths and narrow scour areas cause strong multipath reflections of the signals, which require extensive manual post-processing of the measurement data. This includes manually cleaning the point cloud of multipath reflections and filtering the data sets for subsequent DTM creation. DTM creation of the recorded underwater area with a grid width of 20 cm 2) Terrestrial photogrammetric survey and evaluation of the scour edge areas Due to the greatly reduced water level caused by the pumping out of the Wien River, the scours are no longer covered with water up to their upper edge. This means that, contrary to the original plan, the scour edge areas cannot be recorded with the echo sounder. For this reason, it was decided to carry out a photogrammetric survey and evaluation of the scour edge areas. The photogrammetric images are analyzed using the structure from motion (SFM) method and the surface is displayed as a 3D point cloud. The point cloud is filtered and artifacts from the evaluation are removed manually. In order to merge the underwater DTMs with the surface DTMs of the scour areas, the water-covered areas of the surface model are masked out manually.