Time-Adaptive Change Analysis through Extension of the M3C2 Algorithm using Multi-Modal Laser Scanning Data in a Salt Marsh Environment

We mapped the riverbed through a 28 km canyon in southern France using airborne laser measurements, where field surveys are difficult and risky. By reprocessing the full recorded signal and combining it with targeted sonar checks, we recovered deeper and more complete underwater terrain than standard approaches. The resulting riverbed elevation model preserves key channel shapes needed for improved flood simulations, habitat assessment, and river management.

River bedrock erosion can occur by abrasion and by the removal of entire blocks. We observe that when there is no or few fractures most erosion occurs by abrasion, whereas with more fractures, blocks can be removed at once leading to different patterns of erosion and riverbed morphology. Fractures affect barely mean erosion rate but change the location and occurrence of block removal. Our results highlight how river bedrock properties influence erosion processes and thus landscape evolution.

In natural rivers, flow variability and sediment heterogeneity affect how sediment grains are transported. A unique law that predicts the total amount of sediment transportable by a river for a wide range of sediment mixtures and flow conditions exists, but unclear trends remain. Two improvements to this law – a standardized onset of sediment transport and a common reference transport height across all sizes – appear to be critical to having a functional multi-grain-size total sediment load.

This paper describes a dataset that includes input, output, and validation data for the simulation of flash flood hazards and three specific flash flood events in the French Mediterranean region. This dataset is particularly valuable as flood mapping methods often lack sufficient benchmark data. Additionally, we demonstrate how the hydraulic method we used, named Floodos, produces highly satisfactory results.

We present a method to extract surface change information from 4D time series of topographic point clouds recorded with a terrestrial laser scanner. The method uses sensor information to spatially and temporally smooth the data, reducing uncertainties. The Kalman filter used for the temporal smoothing also allows us to interpolate over data gaps or extrapolate into the future. Clustering areas where change histories are similar allows us to identify processes that may have the same causes.

The rock glacier in Äußeres Hochebenkar (Austria) moved faster in 2021–2022 than it has in about 70 years of monitoring. It is currently destabilizing. Using a combination of different data types and methods, we show that there have been two cycles of destabilization at Hochebenkar and provide a detailed analysis of velocity and surface changes. Because our time series are very long and show repeated destabilization, this helps us better understand the processes of rock glacier destabilization.

The morphology and size of sediments influence erosion efficiency, sediment transport and the quality of aquatic ecosystem. In turn, the spatial evolution of sediment size provides information on the past dynamics of erosion and sediment transport. We have developed a new software which semi-automatically identifies and measures sediments based on 3D point clouds. This software is fast and efficient, offering a new avenue to measure the geometrical properties of large numbers of sediment grains.

3D point clouds, acquired by laser scanning, allow us to retrieve information about forest structure and individual tree properties. We conducted airborne, UAV-borne and terrestrial laser scanning in German mixed forests, resulting in overlapping point clouds with different characteristics. From these, we generated a comprehensive database of individual tree point clouds and corresponding tree metrics. Our dataset may serve as a benchmark dataset for algorithms in forestry research.

Landscape evolution is highly dependent on climatic parameters, and the occurrence of intense precipitation events is considered to be an important driver of river incision. We compare the rate of erosion with the variability of river discharge in a mountainous landscape of SE France where high-magnitude floods regularly occur. Our study highlights the importance of the hypotheses made regarding the threshold that river discharge needs to exceed in order to effectively cut down into the bedrock.

Both landslide mapping and volume estimation accuracies are crucial to quantify landscape evolution and manage such a natural hazard. We developed a method to robustly detect landslides and measure their volume from repeat 3D point cloud lidar data. This method detects more landslides than classical 2D inventories and resolves known issues of indirect volume measurement. Our results also suggest that the number of small landslides classically detected from 2D imagery is underestimated.