Abstract:

Remote sensing technologies are now prevalent in geohazard monitoring applications. Laser scanners
(LiDAR), photogrammetry, and satellite based topographical measurements can be used to map various
geomorpholigies, natural terrains, and man made infrastructures. Change detection analysis with
topographical data sets captured at certain frequency in time can denote failure precursors, active
landslide events, and analyse events a-posteriori. Change detection in time is often carried at high
resolution and low temporal frequency. Dense data sets reduce considerably the inherent uncertainty
arising from superficial roughness and statistical spread between two series of surveys. Long-term, high-
resolution monitoring thus allow for precise measurements and the detection of relatively low change
detection thresholds. Such application is not readily applicable to the detection of rapidly progressing
events. In situations where statistical outliers occur such as intense rains, or earthquakes, landslides may
be triggered and not captured within the time-frame required to act and mitigate. The present study
investigates low-resolution, high-temporal frequency measurements as an option for capturing rapidly
evolving events.
In this work, a low-cost fixed laser scanner was connected to a small Raspberry Pi to collect point cloud
frames at hourly intervals. The montage consisted of the lidar-computer combination mounted on a
tripod anchored to the ground. All electronic hardware was packaged in a small pelican box for
environmental protection. This poster describes the montage, material required to assemble, and
installation protocol. Special considerations were given for rapid deployment with limited labor. To test
the monitoring set-up, an artificial pile of humid <4mm material was assembled in a local quarry. The pile
was partially excavated at the toe to achieve a progressive failure as the material dried up. Monitoring of
the pile was performed for approximately 3 weeks with hourly readings. A high-resolution scan was
taken at the onset of the test for reference. Results obtained are analyzed and discussed in the poster. A
discussion is provided on uncertainty associated with topographical measurements collected during this
experiment.

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Ms. Arapi Kandiah

Biography