Monthly Archives: February 2015

SHORT COURSE at EGU2015

Hello to everyone,

We will be presenting a Short Course at the European Geosciences Union General Assembly. The course is entitled “Use of 3D point clouds in Geosciences: Acquisition, Processing and Applications” and the pdf of the Powerpoint presentations can be downloaded here.

DATE AND PLACE: Monday 13th of April, from 17:30 to 19:30 in room B7. If you are a PhD student or an Early Stage Researcher, you are welcome to assist.

CONTENTS OF THE COURSE

Introduction to course + speakers (AA+MJ) 5’
1. Short introduction to LiDAR sensors + photogrammetry (MHD) 15’ (20’)
2. Point cloud acquisition, pre-processing and available software (AA) 15’ (35’)
3. 3D geological mapping (FH) 15’ (50’)
——10 min. Pause —— 10’ (1h)
4. Rock structural characterisation (AG) 15’ (1h 15)
5. Monitoring: Change detection + Deformation (DC) 15’ (1h 30)
6. Perspectives and discussion (AA) 15’ (1h 45)

AVAILABLE INFORMATION:

The PowerPoints of the course and some RAW 3D point clouds will be uploaded here some days before the beginning of the course. Some other information can be found here: http://meetingorganizer.copernicus.org/EGU2015/session/19506

Also, we want to account with your vision, in case you’ll be interested in contributing for the last part of our course (“6. Perspectives and discussion”), you can contact us and send us your contribution.

Special Issue “Use of LiDAR and 3D point clouds in Geohazards”

We have been invited for edit a special issue at Remote Sensing journal entitled: “Use of LiDAR and 3D point clouds in Geohazards”

Deadline for manuscript submissions: 31 May 2015

SPECIAL ISSUE CONTENTS:

Contributions aiming to use 3D point clouds for investigating natural phenomena (including ground deformation, landslides, floods, earthquakes, volcanoes, soil erosion, etc.) that pose serious risks to human beings or infrastructures will be much appreciated in this special issue. We aim to put together innovative contributions about novel processing techniques and original applications of three-dimensional techniques in Geohazards. Some examples include, but are not limited to:

  • Novel technologies or procedures for dynamic acquisition of 3D point clouds
  • New computational methods related with the monitoring of natural phenomena
  • Semi-automatic extraction of terrain features related with the characterization of geological hazard
  • Integration of very high quality data for improving the modeling of geohazards
  • Recent case studies: innovative analysis and interpretation of Geohazards
  • Use of three-dimensional systems in laboratory scale experiments (micro scale)
  • Improvements in regional mapping derived from high quality 3D data
  • Pioneering initiatives for the creation of 3D databases, web visualization and data sharing
  • Further related topics.

Authors are required to check and follow specific Instructions to Authors, see https://dl.dropboxusercontent.com/u/165068305/Remote_Sensing-Additional_Instructions.pdf.

Yours sincerely,

Prof. Michel Jaboyedoff, Dr. Antonio Abellan, Dr. Marc-Henri Derron (Guest Editors)

More information here: http://www.mdpi.com/journal/remotesensing/special_issues/geohazards

Alexandre Loye: Budgeting rockfall and modeling sediment delivery in torrent systems

Alexandre Loye
Director: Prof. Michel Jaboyedoff
Jury: Prof. Klaus Holliger, Prof. Michel Jaboyedoff, Dr. Marc-Henri Derron, Dr. Frédéric Liébault, Dr. Francesco Brardinoni, Prof. Oldrich Hungr

This thesis is a compilation of projects to study sediment processes recharging debris flow
channels. These works, conducted during my stay at the University of Lausanne, focus
in the geological and morphological implications of torrent catchments to characterize
debris supply, a fundamental element to predict debris flows. Other aspects of sediment
dynamics are considered, e.g. the coupling headwaters – torrent, as well as the development of a modeling software that simulates sediment transfer in torrent systems.

The sediment activity at Manival, an active torrent system of the northern French Alps,
was investigated using terrestrial laser scanning and supplemented with geostructural investigations and a survey of sediment transferred in the main torrent. A full year of sediment flux could be observed, which coincided with two debris flows and several bedload transport events. This study revealed that both debris flows generated in the torrent and were preceded in time by recharge of material from the headwaters. Debris production occurred mostly during winter-early spring and was caused by large slope failures. Sediment transfers were more puzzling, occurring almost exclusively in early spring, subordinated to runoff conditions, and in autumn during long rainfall events. Intense rainstorms in summer did not affect debris storage that seems to rely on the stability of debris deposits.

The morpho-geological implication in debris supply was evaluated using DEM and field
surveys. A slope angle-based classification of topography could characterize the mode
of debris production and transfer. A slope stability analysis derived from the structures
in rock mass could assess susceptibility to failure. The modeled rockfall source areas
included more than 97% of the recorded events and the sediment budgets appeared to be
correlated to the density of potential plane failure. This work showed that the analysis
of process-related terrain morphology and of susceptibility to slope failure document the
sediment dynamics to quantitatively assess erosion zones leading to debris flow activity.

The development of erosional landforms was evaluated by analyzing their geometry with
the orientations of potential rock slope failure and with the direction of the maximum
joint frequency. Structure in rock mass, but in particular wedge failure and the dominant
discontinuities, appear as a first-order control of erosional mechanisms affecting bedrockdominated catchments. They represent some weaknesses that are exploited primarily by mass wasting processes and erosion, promoting not only the initiation of rock couloirs and gullies, but also their propagation. Incorporating the geological control in geomorphic processes contributes to better understand the landscape evolution of active catchments.

A sediment flux algorithm was implemented in a sediment cascade model that discretizes
the torrent catchment in channel reaches and individual process-response systems. Each
conceptual element includes in a simple manner geomorphological and sediment flux information derived from GIS complemented with field mapping. This tool enables to simulate sediment transfers in channels, considering evolving debris supply and conveyance, and helps reducing uncertainty inherent to sediment budget prediction in torrent systems.

This thesis aims in a modest way to shine light on some aspects of sediment dynamics of
torrent systems.