Unmanned Aircraft System-derived terrain information J. van der - - PowerPoint PPT Presentation

Permafrost dynamics and infrastructure impacts revealed by Unmanned Aircraft System-derived terrain information

• J. van der Sluijs *, R. H. Fraser, S. Kokelj, J. Tunnicliffe, I. Olthof

NWT Centre for Geomatics, Canada Centre for Mapping and Earth Observation, NWT Geological Survey, University of Auckland

Challenges

• Intensification of climate-driven

thermokarst

• Thaw-related infrastructure problems

Information gaps

• Understanding magnitudes of landscape

change

• Need to bridge spatial/temporal gap

through flexible solution (1 ha to 1 km2) Unmanned Aircraft System (UAS)

• Reveal information about processes

previously difficult or impossible to study: – Retrogressive thaw slumps – Quarry/borrow pits in permafrost – Injection ice along roads

Introduction

Kokelj et al. (2015). Global and Planetary Change

GENERAL APPROACH:

EQUIPMENT, DATA ACQUISITION, DATA PROCESSING

Bradatech - RX4-S Surveyor w. 20 MP Sony RX100 III Bradatech - Sky Hero PX8 Plus 1000 Octocopter with Sony A6000 DJI - Inspire Pro, Phantom 4 Pro, Phantom 3 Advanced, Phantom 2 Sensefly - eBee Plus RTK/PPK

Flight planning Structure-from-Motion Photogrammetry (Pix4D) into 3D pointclouds (+DSM, ortho) 3

Acquisition of overlapping photos

UAS Monitoring of Retrogressive Thaw Slumps (Behaviour in space & time)

2015

Fill Debris Tongue Slumps Failure precursor

2016

Embankment Failure

UAS Monitoring of Retrogressive Thaw Slumps and Creep Behavior of Roadside Fill

* CosiCorr Image Correlation Change Detection (Leprince 2007 IEEE Trans. Geosci. Remote Sens)

Daily repeat surveys Annual repeat surveys

0-20 cm movements 0-45 cm movements

Slump: rapid daily movement due to slope and saturation Engineered slope: relatively stable yet continued annual creep

UAS Monitoring of Retrogressive Thaw Slumps (Dynamics & volumes of earth flows)

A C D B

UAS Monitoring of Retrogressive Thaw Slumps (Failure modes, morphological processes & geotechnical properties)

Peat deposit Saturated fine- grained tills, Quickly warming

Ice-face at the headwall

Drainage tracks

Undisturbed riparian drainage

Ice-face at the headwall

Drainage capture

• Headwall retreat is concentrated

in areas indicated by colder temperatures

• Saturated materials warm quickly
• New phenomenon: slump retreat of drainage areas; influencing trajectory of change

Semi-stable headwall

Challenges UAS Monitoring of Quarry/Borrow Pit Stability

Slope instabilities Active thaw slump, flow slide 2016 2017

UAS to monitor compliance, change trajectories; inform mitigation and best practices

UAS Monitoring of Injection Ice (Dempster Highway)

2016 2017

* Ground ice formed during active-layer freezeback, where confining aquifer is developed between permafrost table and downward frost front

Inuvik-to-Tuktoyaktuk Hwy

Permafrost table Frost front

Annual change (July 2016 & July 2017)

Elevation Active Layer thickness

• UAS provide a flexible means for visualizing permafrost dynamics and

infrastructure impacts

• Strong potential of UAS time-series analyses to study thermal,

vegetative, hydrologic, and geomorphic processes and feedbacks

Conclusion

• Department of Environment and Natural Resources –

Cumulative Impact Monitoring Program

• Natural Resources Canada - Polar Continental Shelf Program
• Tetlit Gwich’in (logistical support, assistance)
• Inuvialuit Land Administration
• Department of Infrastructure
• Department of Lands

Acknowledgements