Category Archives: Blog

3D modelling the oak of Napoléon

The Risk group participed in a study conducted by researchers at the University of Lausanne whose results where published in Nature Plants . Results reveal that the genome of oak Napoleon has evolved little during its first 234 years of existence.

The 3D modelling was carry out using a LiDAR. Terrestrial LiDAR scans were taken around the oak every 60°. The six scans were cleaned from background objects and aligned in order to generate a 1.2 million 3D-points cloud. The mesh from the 3D points cloud was colourized to produce the final 3D oak model.

Sources: Nature Plants, Le Temps, 24Heures, News Unil, Napoleome

Oak of Napoleon from our automatic camera along seasons:

Oak scanning:

3D-printed model of the oak:

Near-infrared image of the oak:

Andorra-la-Vella : Lidar monitoring

The Risk Analysis Group (C. d’Almeida, F.Noël) spent a week in the principality of Andorra to carry out lidar survey. The city of Andorra-la-Vella, located in the hearth of the Pyrenees is a very dense city surrounded by landslides and active cliffs.

Lidar and photographs survey

Lidar and photographs survey of 12 sites were performed. These sites were previously monitored by the Risk Analysis Group (Antonio Abellan) in 2009 and 2012. Exploiting the lidar scans will permit to quantify the erosion activity of the cliffs and detect potential instabilities. The Risk Analysis Group thanks the geo-hazard expert Joan Torrebadella from Georisk-international for his warm welcome, and accompanying during this week.

Lidar scan

Risk Group at the 15th Swiss Geoscience Meeting in Davos, Switzerland

The 15th Swiss Geoscience Meeting, organized by the WSL-Institute for Snow and Avalanche Research SLF and the Platform Geosciences of the Swiss Academy of Sciences SCNAT, was held on 17th and 18th of November 2017 in Davos (Switzerland).

16 different sessions were planned during this meeting and the Risk Group members contributed to several presentations mainly in the “Progress in assessment of hazards and risks in mountain regions” session. Presentations are below:

5 Talks:

Aye Z.C., Artigue V., Jaboyedoff M., Derron M., Gerber C., Lévy S. An open-source webGIS platform for risk management of natural hazards in Canton Vaud

Derron M.-H., Rouyet L., Guerin A., Lefeuvre C., Jaboyedoff M. Imaging of non-gravitationnal movements in rock faces

Franz M., Rudaz B., Jaboyedoff M., Podladchikov Y. Coupling SLBL with shallow water model to assess landslide-generated tsunami hazard at Oeschinensee

Jaboydedoff M., Artigue V., Aye Z.C., Derron M.-H., Gerber C., Lévy S. From the average velocities of deep seated landslides to intensity-frequency scenarios

Noël F., Wyser E., Jaboyedoff M., Derron M. Real-size rockfall experiment: How different rockfall simulation impact models perform when confronted with reality?

8 Posters:

Meier C., Derron M., Jaboyedoff M., Gerber C., Artigue V. Inventory of shallow landslides in regards to their frequency in the Canton of Vaud (Switzerland

D’almeida C., Guerin A., Jaboyedoff M., Hantz D. Model and cartography of the Saint-Eynard cliff erosion by rockfalls

Wyser E., Jaboyedoff M. Dramatic granular impact(s): a plastic- or friction-dominated transition phase

Noël F., Wyser E., Jaboyedoff M., Derron M. Real-size rockfall experiment: A relatively simple method to acquire 3D impact characteristics from video footage

Nduwayezu E., Jaboyedoff M., Derron M.-H, Nsengiyumva J.-B., Twarabamenye E. Pression démographique et outils analyse d’aléas et risques gravitaires au Rwanda.

Ben Hammouda M., Jaboyedoff M., Derron M.H., Bouaziz B. Rockfall hazard evaluation in a touristic area of northern Tunisia using SFM photogrammetry in a zero data site

Voumard J., Derron M.-H., Jaboyedoff M. Characterization of natural hazard events affecting the Swiss transportation networks from 2012 to 2016

1 poster for the “Hydrology, Limnology and Hydrogeology” session:

Kouame A.A., Jaboyedoff M., Goola Bi Tie A., Derron M., Kouamé Kan J. Assessment of potential pollution of an unconfined aquifer in Abidjan by hydrocarbons

The full proceedings volume of VGC2016 is available at: https://geoscience-meeting.ch/sgm2017/wp-content/uploads/SGM_2017_Abstract_Volume.pdf

Scientific stay of Teresa Gracchi in the group RISK

Teresa Gracchi will stay for 6 months in the group RISK at UNIL. Teresa is a joint-PhD student at the Department of Civil and Environmental Engineering of the University of Florence and at the Faculté des Géosciences et de l’environnement of the University of Lausanne, in the framework of the International Doctorate in Civil and Environmental Engineering program. Her research involves the use of innovative techniques for landslide monitoring, such as wireless sensor networks. In particular, she deals with a low-cost and easy to install system suitable for emergency monitoring, based on ultra-wideband technology. During her stay at UNIL, she will focus in viewshed analysis from LIDAR point cloud, to develop a tool that allows finding the best positions to install a wireless sensor network.

Welcome Teresa and we wish you the best for your project

4th Slope Tectonics Conference – Kyoto Oct. 2017

The 4th Slope Tectonics Conference was held from 14 to 18 October 2017 in Japan. It started with two days of presentations at the University of Kyoto and was followed by three days of fieldtrip in the Kii penninsula. As a reminder, the Slope Tectonics Conferences were initiated in Lausanne in 2008 (and then in Vienna in 2011 and Trondheim in 2014).

Michel Jaboyedoff and Marc-Henri Derron took part to this conference with two oral presentations:
3D failure surface and volume estimation of large rock slope instabilities: a review of a bottleneck problem
Slope deformation imaging of sandbox analogue models (LiDAR and InSAR)

Flight at Bondo (GR)

Five people of the Risk Analysis Group went to Bondo, Canton of Graubünden, on 29 September 2017 to make a helicopter flight along the debris flow and cliff collapse of the August event. During a 25 minutes flight from the village of Bondo to the Piz Cengalo through the Val Bondasca, 11’400 pictures were taken by automatically and manually operated cameras . Those data will be used to get 3D models of the area by SfM processing.

 

Fieldcamp in Barcelonnette 2017


Beginning of June 2017, the field-camp in risk and slope processes for master students took place in the valley of Ubaye, at Barcelonnette (France). During almost two weeks, the students have mapped the Lavalette landslide, analysed the stability of a large rock wall, made rockfall mapping and numerical modelling, and discovered the debris flows mitigation measures in the Riou Bourdou watershed.

This camp was made possible thanks to the center Seolane and the kindness of Georges Guiter from RTM: http://eost.u-strasbg.fr/seolane/

HYDRUS CONFERENCE AND WORKSHOP, PRAGUE 2017- CZECH REPUBLIC

HYDRUS short course and 5th International Conference “Hydrus Software Applications to Subsurface Flow and Contaminant Transport Problems”, 26-30 march 2017, Prague

Agnes Kouame, PhD student in the Risk group, attended the Hydrus short course on 28-29 Mars 2017 at the Faculty of Agrobiology, Food and Natural Resources of the Czech University of Life Sciences. This theoretical course allowed students to understand the conceptual and mathematical description of water flow and solute transport processes in the vadose zone and groundwater with HYDRUS 1D/2D. It included practical sessions with HYDRUS and its additional modules like ROSETTA, HP1 and UNSATCHEM.

The 5th International Conference on Hydrus Software Applications to Subsurface Flow and Contamination Problems was an opportunity for Agnes to meet Professors Van Genuchten and Dr. Jirka Šimůnek authors of HYDRUS code.

https://www.pc-progress.com/en/Default.aspx?courses-2017#k3

STAY OF DR KOUAME KAN JEAN AT THE UNIVERSITY OF LAUSANNE

From 15 to 26 March 2017, Dr. Jean Kouamé visited the risk group at the University of Lausanne to help on the finalization of Amenan Agnès Kouamé’s thesis directed by Prof. Michel Jaboyedoff. During his visit Dr Kouamé gave a presentation on the “Contribution of the modeling in the determination of the protection perimeters of the catchments: case of the water table of Bonoua (South-east of the Ivory Coast).

Workshop about Monitoring and characterization tools dedicated to rock instabilities for practitioners in Jura canton: “Outils de surveillance et de caractérisation des instabilités rocheuses”

Les Forges (JU, Switzerland) unstable column (with the road below)

The risk group (C. Lefeuvre, J. Voumard, M.-H. Derron, M. Jaboyedoff) provided a course on 5th May 2017 in the Café de la Poste, Glovelier (JURA) dedicated to “Outils de surveillance et de caractérisation des instabilités rocheuses » (Monitoring and characterization tools dedicated to rock instabilities) organized by the head of natural hazard of the canton du Jura: Dr. Andrea Pedrazzini.

This workshops followed a study performed by our group about a rock slope in limestone of the Jura mountain (see pictures).

Group of participants viewed by a DJI drone on the site of les Forges (JU)