[{"pid":"wsl:34019","object_url":"https://www.dora.lib4ri.ch/wsl/islandora/object/wsl:34019","citation":{"WSL":"Baumer J., Metzger N., Hafner E.D., Caye Daudt R., Wegner J.D., Schindler K. (2023) Automatic image compositing and snow segmentation for alpine snow cover monitoring In Swiss conference on data science (SDS). 2023 10th IEEE Swiss conference on data science (SDS). Piscataway: IEEE. 77-84. https://doi.org/10.1109/SDS57534.2023.00018"},"doi":"10.1109/SDS57534.2023.00018","abstract":"Accurate snow cover maps are an important tool in a large variety of applications including avalanche research. The WSL Institute for Snow and Avalanche Research (SLF) has developed a snow cover mapping system for the Dischma valley in Davos, based on ground-based cameras. Their goal has been to validate snow-cover maps derived from satellite data. In the currently implemented system, several steps require manual work. The goal of this paper is to automate SLF's approach by applying a deep learning framework. For the training of our models, we have access to data from multiple cameras mounted in the Dischma valley. In our approach, we first apply deep learning to perform fog classification and then to do pixel-wise snow segmentation. Unlike the current procedure our method is independent of image- and camera-specific thresholds. In our experiments, we compare a model that is trained on images from all cameras to camera-specific models for both tasks. For the fog classification, we aim for a higher recall to be able to detect most of the foggy images. We show that, when tuned to achieve the same precision as the baseline, our model improves recall by 17%. For the snow segmentation, we evaluate our models based on the Fl-score. When using our fully automated machine learning model without any manually selected thresholds, we achieve a higher Fl-score only for a part of the cameras in the valley, and on average, this comes at a cost of 2.3%. We also show that for the case of a new camera being mounted in the Dischma valley, our models for both tasks can still be used for that new camera and will achieve similar results compared to the currently mounted cameras."},{"pid":"wsl:35230","object_url":"https://www.dora.lib4ri.ch/wsl/islandora/object/wsl:35230","citation":{"WSL":"Bebi P., Piazza N., Ringenbach A., Caduff M., Conedera M., Krumm F., Rigling A. (2023) Schutzwirkung und Resilienz von Gebirgswäldern nach natürlichen Störungen In P. Bebi & J. Schweier (Eds.), WSL Berichte: Vol. 144. Aus Störungen und Extremereignissen im Wald lernen. Birmensdorf: Eidg. Forschungsanstalt für Wald, Schnee und Landschaft WSL. 41-48. https://doi.org/10.55419/wsl:35230"},"doi":"10.55419/wsl:35230","abstract":"Natürliche Störungen gehören zu den grössten Herausforderungen für die Erhaltung der Schutzfunktionen unserer Wälder. Die Förderung einer möglichst hohen Resilienz gegenüber solchen Störungen wurde in den letzten Jahrzehnten zu einem immer wichtigeren Bestandteil der Schutzwaldbewirtschaftung. In diesem Artikel geben wir einen Überblick zum Einfluss von natürlichen Störungen auf die Schutzfunktion gegenüber Naturgefahren, wobei wir Resultate aus kürzlich an der WSL und der ETH abgeschlossen Dissertationen aufgreifen. Darauf aufbauend und vor dem Hintergrund der erwarteten weiteren Zunahme von Störungen und Extremereignissen diskutieren wir, wie die zukunftige Resilienz von Schutzwälder gefördert werden kann.

Natural disturbances are among the greatest challenges for the management of forests with a protective role against natural hazards. Promoting the highest possible resilience related to natural disturbances has thus become an increasingly important part of mountain forest management in recent decades. In this article, we present results of recently finalized PhD dissertations and provide an overview on the effect of natural disturbances on the protective function against natural hazards. Based on this overview and an expected further increase in the frequency and intensity of extreme events and natural disturbances in mountain forests, we discuss how the resilience of protective forests to future extreme events may be promoted."},{"pid":"wsl:34704","object_url":"https://www.dora.lib4ri.ch/wsl/islandora/object/wsl:34704","citation":{"WSL":"Bebi P., Allgaier Leuch B., Bugmann H., Conedera M., Frehner M., Insinna P., … Zürcher S. (2023) Wildhuftiere und Waldverjüngung: Wenn die Zeit davonläuft Schweiz. Z. Forstwes. 174(5), 274-279. https://doi.org/10.3188/szf.2023.0274"},"doi":"10.3188/szf.2023.0274","abstract":"Der rasch fortschreitende Klimawandel gefährdet wichtige Waldleistungen, da sich die Wälder den sich verändernden Bedingungen nicht schnell genug anpassen können. Damit die Waldleistungen auch in Zukunft erbracht werden können, ist eine möglichst artenreiche Verjüngung zukunftsfähiger Baumarten zentral. So werden die Wälder gegenüber Störungen resilienter. Der in vielen Regionen der Schweiz seit Jahrzehnten sehr hohe Verbiss der Waldverjüngung durch Wildhuftiere stellt in dieser Hinsicht eine grosse Herausforderung dar. Verschiedene Beispiele zeigen, dass eine ausreichende Waldverjüngung nur möglich ist, wenn nebst waldbaulichen Massnahmen eine gezielte, regional differenzierte Reduktion des heutigen Wildbestandes erfolgt. Dies wiederum erfordert eine konstruktive und auf gemeinsamen Zielen beruhende Zusammenarbeit zwischen Jagd und Forst sowie gesellschaftlich-politische Rahmenbedingungen, die diese Zusammenarbeit im Sinn des nationalen Gesetzesauftrags und der Erfüllung der zukünftigen Aufgaben des Waldes fördern und wertschätzen."},{"pid":"wsl:34980","object_url":"https://www.dora.lib4ri.ch/wsl/islandora/object/wsl:34980","citation":{"WSL":"Berger C., Zimmermann F., Mauerhofer R., Christen M. (2023) MurGame: Protect your village from debris flows! In M. Pirulli, A. Leonardi, & F. Vagnon (Eds.), E3S web of conferences: Vol. 415. 8th international conference on debris flow hazard mitigation (DFHM8). Les Ulis Cedex A: EDP Sciences. 07002 (4 pp.). https://doi.org/10.1051/e3sconf/202341507002"},"doi":"10.1051/e3sconf/202341507002","abstract":"Past debris flow events, like in Bondo (2017) and Brienz (2005) in Switzerland have been heavily covered in the (Swiss) media, illustrating how destructive such events can get. Protection measures play an important role in dealing with natural hazards. Debris flows are considered to be very rare, complex and multidimensional processes. Imagining and foreseeing the course and progression of a debris flow as well as estimating the potential damage and the influence of protection measures is a difficult task. Serious games offer a possibility to simulate these kinds of situations. With the MurGame, we have developed an application for natural hazard prevention. In the three-dimensional, interactive game, a village is created by selecting different objects, such as residential buildings or schools. Debris flow simulations show, which buildings would be destroyed and what damage would occur in the event of a debris flow. Different protection measures can be implemented to protect the village and their effectiveness can be monitored during the simulations. After the event, it is necessary to evaluate which measures offer the desired protection, what they may cost and how the needs of the population are met. The MurGame can be played online at www.murgame.ch."},{"pid":"wsl:32728","object_url":"https://www.dora.lib4ri.ch/wsl/islandora/object/wsl:32728","citation":{"WSL":"Bergfeld B., Van Herwijnen A., Bobillier G., Rosendahl P.L., Weißgraeber P., Adam V., … Schweizer J. (2023) Temporal evolution of crack propagation characteristics in a weak snowpack layer: conditions of crack arrest and sustained propagation Nat. Hazards Earth Syst. Sci. 23(1), 293-315. https://doi.org/10.5194/nhess-23-293-2023"},"doi":"10.5194/nhess-23-293-2023","abstract":"For a slab avalanche to release, we need sustained crack propagation in a weak snow layer beneath a cohesive snow slab – a process we call dynamic crack propagation. Field measurements on crack propagation are very scarce. We therefore performed a series of crack propagation experiments, up to 9 m long, over a period of 10 weeks and analysed these using digital image correlation techniques. We derived the elastic modulus of the slab (0.5 to 50 MPa), the elastic modulus of the weak layer (50 kPa to 1 MPa) and the specific fracture energy of the weak layer (0.1 to 1.5 J m⁻²) with a homogeneous and a layered-slab model. During crack propagation, we measured crack speed, touchdown distance, and the energy dissipation due to compaction and dynamic fracture (5 mJ m⁻² to 0.43 J m⁻²). Crack speeds were highest for experiments resulting in full propagation, and crack arrest lengths were always shorter than touchdown lengths. Based on these findings, an index for self-sustained crack propagation is proposed. Our data set provides unique insight and valuable data to validate models."},{"pid":"wsl:33118","object_url":"https://www.dora.lib4ri.ch/wsl/islandora/object/wsl:33118","citation":{"WSL":"Blatny L., Löwe H., Gaume J. (2023) Microstructural controls on the plastic consolidation of porous brittle solids Acta Mater. 250, 118861 (14 pp.). https://doi.org/10.1016/j.actamat.2023.118861"},"doi":"10.1016/j.actamat.2023.118861","abstract":"Through stochastic-numerical microstructure-based experiments, the plastic consolidation under compression of porous brittle solids, with porosities from 0.25 to 0.75 and a large variety of microstructural characteristics, has been investigated. This was made possible by generating microstructures from Gaussian random fields in order to obtain stochastic ensembles of structures with prescribed properties, which are then simulated within the material point method. Below a critical imposed strain rate, the consolidation behavior is found to be very weakly affected by the degree of heterogeneity and anisotropy. Structures where the solid phase takes up more space than the void phase have a consolidation response approximately independent of the structural geometry and dimensionality (comparing two- and three-dimensional structures). Finally, we show that the consolidation of two-dimensional structures collapses on a single master curve that can be described by a simple function similar to one presented for a completely different system, namely a system of interacting discrete cohesive disks. In this function, we report a universal parameter largely independent of material specifications."},{"pid":"wsl:35137","object_url":"https://www.dora.lib4ri.ch/wsl/islandora/object/wsl:35137","citation":{"WSL":"Bobillier G., Trottet B., Bergfeld B., Simenhois R., van Herwijnen A., Schweizer J., Gaume J. (2023) Supershear crack propagation in snow slab avalanche release: new insights from numerical simulations and field measurements In ISSW proceedings. International snow science workshop proceedings 2023. Bozeman: Montana State University Library. 38-42. "},"doi":"","abstract":"The release process of dry-snow slab avalanches begins with a localized failure within a porous, weak snow layer that lies beneath a cohesive slab. Subsequently, rapid crack propagation may occur within the weak layer, eventually leading to a tensile fracture across the slab, resulting if the slope is steep enough, to its detachment and sliding. The dynamics of crack propagation is believed to influence the size of the release area. However, the relationship between crack propagation dynamics and avalanche size remains incompletely understood. Notably, crack propagation speeds estimated from avalanche video analysis are almost one order of magnitude larger than speeds typically measured in field experiments. To shed more light on this discrepancy and avalanche release processes, we used discrete (DEM: discrete element method) and continuum (MPM: material point method) numerical methods to simulate the so-called propagation saw test (PST). On low angle terrain, our models showed that the weak layer fails mainly due to a compressive stress peak at the crack tip induced by weak layer collapse and the resulting slab bending. On steep slopes, we observed the emergence of a supershear crack propagation regime: the crack speed becomes higher than the slab shear wave speed. This transition occurs if the crack propagates over a distance larger than the super-critical crack length (approximately 5 m). Above the super-critical crack length, the fracture is mainly driven by the slope-parallel gravitational pull of the slab (tension) and, thus, shear stresses in the weak layer. These findings represent an essential additional piece in the dry-snow slab avalanche formation puzzle."},{"pid":"wsl:35345","object_url":"https://www.dora.lib4ri.ch/wsl/islandora/object/wsl:35345","citation":{"WSL":"Bont L., Blattert C., Schweier J., Bührle L., Helzel K., Bebi P., … Nikolova P.S. (2023) Mountain spruce forests as hotspots for EXtremes: optimal allocation of the limited resources of a forest enterprise In WSL Berichte: Vol. 144. Forum für Wissen 2023. Eidg. Forschungsanstalt für Wald, Schnee und Landschaft WSL. "},"doi":"","abstract":""},{"pid":"wsl:33662","object_url":"https://www.dora.lib4ri.ch/wsl/islandora/object/wsl:33662","citation":{"WSL":"Borner J., Bartelt P. (2023) Calculating impact pressures in numerical avalanche and rockfall models In L. Zdravkovic, S. Kontoe, D. M. G. Taborda, & A. Tsiampousi (Eds.), Proceedings 10th NUMGE 2023. 10th European conference on numerical methods in geotechnical engineering. sine loco: International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE). (6 pp.). https://doi.org/10.53243/NUMGE2023-370"},"doi":"10.53243/NUMGE2023-370","abstract":"Calculating contact/impact pressures with numerical finite element software remains a difficult task. It is especially difficult for highly compactable, plastic materials where the elastic fraction of the strain is very small. This is the case in most impact problems in natural hazards. One example is the impact of rockfall dams by large, rotating rocks. Another is the impact of pylons, walls and other obstacles by snow avalanches. We embed work-energy methods within numerical avalanche and rockfall models to make the calculation of impact pressures in natural hazards more applicable for engineering practice. Firstly, we can greatly reduce the computation time and secondly, the input parameters are much more intuitive for practitioners due to the use of purely plastic compactive material behaviour."},{"pid":"wsl:35236","object_url":"https://www.dora.lib4ri.ch/wsl/islandora/object/wsl:35236","citation":{"WSL":"Bottero A., Zürcher S., Bebi P. (2023) Herausforderungen in Gebirgswäldern gemeinsam angehen: wie Forschung und Praxis erfolgreich zusammenarbeiten und voneinander profitieren können In P. Bebi & J. Schweier (Eds.), WSL Berichte: Vol. 144. Aus Störungen und Extremereignissen im Wald lernen. Birmensdorf: Eidg. Forschungsanstalt für Wald, Schnee und Landschaft WSL. 61-65. https://doi.org/10.55419/wsl:35236"},"doi":"10.55419/wsl:35236","abstract":"Angesichts zunehmender Störungsrisiken und anderer Auswirkungen des Klimawandels sind proaktive Bewirtschaftungsansätze und eine effiziente Bewältigung von Störungen in Gebirgswäldern von entscheidender Bedeutung. Eine gute Zusammenarbeit zwischen Forschung und Praxis ist entscheidend, um diese Herausforderungen zu bewältigen. Wir präsentieren zwei Projekte, in denen dies bereits umgesetzt wird: earlyBEETLE und MountEx. Das earlyBEETLE-Projekt konzentriert sich auf die Früherkennung und Bewältigung von Buchdruckerschäden, während das MountEx-Projekt darauf abzielt, Leitlinien für die Bewirtschaftung von Gebirgswäldern unter dem Einfluss extremer Störungen zu entwickeln. Beide Projekte kombinieren sich ergänzende methodische Ansätze und nutzen Synergien zwischen Forschung und Praxis im Hinblick auf die gemeinsame Erarbeitung von umfassenden Lösungen für das Gebirgswaldmanagement in Zeiten des globalen Wandels. Wichtige Erfolgsfaktoren für eine erfolgreiche Zusammenarbeit zwischen Forschung und Praxis sind, dass Praxispartner bereits in einer frühen Phase in die Projektplanung einbezogen werden und dass die Zusammenarbeit sowohl seitens der Forschungs- wie auch der Praxispartner als Chance und Mehrwert gesehen wird.

Mountain forests offer a range of ecosystem services and products. Under increasing disturbance risks and other climate change impacts, proactive management approaches and efficient management of disturbances in mountain forests are crucial. In this context, a good collaboration between research and practice is crucial to address these challenges. Two projects that aim to do this are presented as examples: earlyBEETLE and MountEx. The earlyBEETLE project focuses on early detection and an management of bark beetle damage, while the MountEx project aims to develop guidelines for the management of mountain forests under the influence of extreme disturbances. By combining different data and methods, the two projects demonstrate the increasing recognition of the potential synergies between research and practice and the promising development towards comprehensive solutions for mountain forest management under global change. Important factors for successful cooperation between research and practice are that practice partners are involved in project planning at an early stage and that cooperation is seen as added value by both research and practice partners."},{"pid":"wsl:33072","object_url":"https://www.dora.lib4ri.ch/wsl/islandora/object/wsl:33072","citation":{"WSL":"Bühler Y., Stoffel A., Eberhard L., Bührle L. (2023) Fotogrammetrische Schneehöhenkartierung aus Drohnen-, Flugzeug- und Satellitenbildern In Eidg. Forschungsanstalt für Wald, Schnee und Landschaft, WSL (Ed.), WSL Berichte: Vol. 134. Neue Fernerkundungstechnologien für die Umweltforschung und Praxis. Birmensdorf: Eidg. Forschungsanstalt für Wald, Schnee und Landschaft, WSL. 61-66. https://doi.org/10.55419/wsl:33072"},"doi":"10.55419/wsl:33072","abstract":"Die räumliche Variabilität der Schneedecke im Gebirge wird durch eine komplexe Kombination topographischer und meteorologischer Faktoren beeinflusst. Innerhalb weniger Meter Distanz finden sich schneefreie Stellen, aber auch Mulden mit Schneehöhen von mehreren Metern. Dies hat grosse Auswirkungen auf die Lawinengefahr, die Wasserspeicherkapazität der Schneedecke sowie Flora und Fauna im Gebirge. Meist wird die Schneehöhe im Gebirge mit Punktmessungen an Wetterstationen oder von Hand erfasst. Allerdings können solche Messungen nur ein unvollständiges Bild der tatsächlichen Schneeverteilung zeichnen. Mit neuen Fernerkundungsplattformen wie Drohnen, Flugzeugen oder optischen Satelliten können photogrammetrisch sehr präzise Oberflächenmodelle erstellt werden. Subtrahiert man ein Oberflächenmodell ohne Schneebedeckung von einem Oberflächenmodell mit Schneebedeckung, erhält man eine räumlich zusammenhängende Kartierung der Schneehöhenverteilung. Am SLF werden seit 2010 solche präzisen Schneehöhenkarten erstellt. Diese erweisen sich als wichtige Grundlage für zahlreiche Anwendungen.

The spatial variability of the mountain snowpack is influenced by a complex combination of topographical and meteorological factors. Within a few meters there are snow-free spots, but also hollows with snow depths of several meters. This has a major impact on the risk of avalanches, the water storage capacity of the snowpack and the flora and fauna in the mountains. The snow depth in the mountains is usually recorded with point measurements at weather stations or by hand. However, such measurements can only paint an incomplete picture of the actual snow distribution. With new remote sensing platforms such as drones, airplanes or optical satellites, very precise surface models can be created photogrammetrically. Subtracting a surface model without snow cover from a surface model with snow cover results in a spatially coherent mapping of the snow depth distribution. Such precise snow depth maps have been created at the SLF since 2010. These prove to be an important basis for numerous applications."}]

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