Effects of climate change and periglaciation on landslide dynamics

Professor Choi, Clarence Edward   (Principal Investigator (PI))

18

2019-10-01

2021-03-31

150000

Effects of climate change and periglaciation on landslide dynamics

Climate change, Landslides, periglaciation

Geotechnical

Engineering (E)

201904185009

Seed Fund for Basic Research for New Staff

2019

Completed

The United Nations Intergovernmental Panel on Climate Change reaffirmed the unequivocal warming of the Earth’s atmosphere due to anthropogenic causes (Stocker 2014). Further increase in temperature is expected to cause unpredictable geomorphological changes in mountainous regions around the world. These changes include geohazards such as landslides. Froude and Petley (2018) reported that surges in the number of annual fatal landslides coincide with climate anomalies. At present, projected changes from climate models are rarely used to reveal how evolving geomorphology may trigger geohazards and how sensitive prevailing conditions are to changing climate variables. Warming of the earth significantly affects periglacial activity (Knight 2009), which is the seasonal freezing and thawing of the earth’s glacial and permafrost areas. More than 24% of the earth’s surface, which is about some 22 million square kilometers, is affected by permafrost (Lemke et al. 2007). Currently, permafrost is melting at an unprecedented rate in human history. Thawing of permafrost in mountainous regions not only causes slope instability, but can release large volumes of sediment into landslide catchments (Fyffe et al. 2019). These sediments can amplify the scale of flow-like landslides if they are initiated by ensuing rainfall episodes. Although these processes are often mentioned in literature, little efforts have been paid to reveal the fundamental mechanisms of these processes to help scientists and engineers to identify the most critical and future geomorphological settings. Another important feature of periglaciation is how channel morphology changes (Lewkowicz and Harris 2005). Seasonal cycles of freezing and thawing can significantly alter the complex network of channels where landslides flow through. This process is called avulsion (De Haas et al. 2016). This includes changing the slope of existing channels or the formation of landslide dams. A consequence of avulsion is that landslides, such as debris flow, may deviate from their predicted flow paths, thereby presenting risks to downstream facilities that were previously thought to be safe. Improving understanding of avulsion from periglaciation is critical for future debris flow hazard assessment (Friele et al. 2000). This proposed research project covers a new topic that has yet to be explored in detail. More specifically, the mechanisms of initiation and transportation of landslides from periglaciation remains poorly understood because glaciers are situated in high-altitude areas and the fundamental failure and initiation mechanisms are rarely observed. Further complicating matters, phase transformation of soil and its large deformation when it is subjected to seasonal thawing and and freezing is a behavior that is not easily captured using existing constitutive models. The research objectives of this proposed project are: (i) to develop a novel periglacial flume to model freezing and thawing of an inclined soil bed; (ii) to reveal the fundamental mechanisms of periglaciation on avulsion; (iii) to study the effects of channel inclination and freezing and thawing cycles on avulsion; and (iv) to produce a unique set of high-quality experimental data for calibrating numerical models. References De Haas, T., Van Den Berg, W., Braat, L., and Kleinhans, M.G. (2016). Autogenic avulsion, channelization and backfilling dynamics of debris‐flow fans. Sedimentology 63(6): 1596-1619. Friele, P.A., Ekes, C., and Hickin, E.J. (2000). Evolution of Cheekye fan, Squamish, British Columbia: Holocene sedimentation and implications for hazard assessment. Canadian Journal of Earth Sciences 36(12): 2023-2031. Froude, M.J., and Petley, D. (2018). Global fatal landslide occurrence from 2004 to 2016. Natural Hazards and Earth System Sciences 18: 2161-2181 Fyffe, C.L., Brock, B.W., Kirkbride, M.P., Mair, D.W.F., Arnold, N.S., Smiraglia, C., Diolaiuti, G., and Diotri, F. (2019). Do debris-covered glaciers demonstrate distinctive hydrological behaviour compared to clean glaciers? Journal of Hydrology 570: 584-597. Knight, J., and Harrison, S. (2009). Sediments and future climate. Nature Geoscience 2(4): 230. Lemke, P., Ren, J., Alley, R.B., Allison, I., Carrasco, J., Flato, G., Fujii, Y., Kaser, G., Mote, P., Thomas, R.H., and Zhang, T. (2007). Observations: changes in snow, ice and frozen ground. CRC-Antarctic Climate & Ecosystems. Lewkowicz, A.G., and Harris, C. (2005). Morphology and geotechnique of active-layer detachment failures in discontinuous and continuous permafrost, northern Canada. Geomorphology 69(1-4): 275-297. Stocker, T. (2014). Climate change 2013: the physical science basis: Working Group I contribution to the Fifth assessment report of the Intergovernmental Panel on Climate Change. Cambridge University Press.