Course:EOSC311/2020/Sustainable Communities: Landslide Risk in Vancouver

Introduction

Landslides are natural hazards that often occur in areas with a steep topography, for instance, in mountainous and coastal geographies like Vancouver, British Columbia. The Sea to Sky corridor, which is 135 km long through the Coast Mountains in British Columbia, has experienced many landslides over time which posed a threat to those who passed through it. Blais-Stevens et al. (2012) state that 155 landslides have been reported within this corridor over the last 154 years. Additionally, the authors highlight how landslides are frequent in the southern part of the corridor, near Vancouver, which consequentially poses a larger threat to communities and infrastructure built in these vulnerable areas . Therefore, with an expanding population and increasing urban development, it becomes more important to mitigate risks to the community and the environment.

Connection to my Major

As our global climate is changing, the word 'sustainability' is being used more frequently in dialogues surrounding public and environmental well-being. The National Geographic encyclopedic entry on sustainability defines it as a way of conserving our natural resources for present and future balance, since we are currently depleting these resources at a faster rate that our planet can support . Both Geology and Geography disciplines teach how to conserve these resources and research sustainable ways to support the earth's balance. With my major, Environment and Sustainability in the Geography department, I research ways to minimize the human impact on the planet. Additionally, I aim to analyze the political, social and economic forces at work behind environmental issues in order to find the most sustainable solutions. This also involves identifying the magnitude of the risk and who is affected by it. My goal is to find ways to mitigate or minimize environmental issues linked to climate change, and this is made possible through the work of geologists. The scientific studies tackled by geologists form the foundation of what we know about the earth's processes and principles. Thus, both of these disciplines work in tandem to discover ways to reduce our carbon footprint.

Why I Chose this Topic

I chose this topic since I am interested in the environmental risks and hazards associated with the diverse topography of Vancouver. I am intrigued with the inter-connectivity of geological processes; for instance, how soil composition, climate, slope, and plate tectonics are linked to landslides. Vancouver, which has experienced many landslides in the past, is an interesting place of study to start. I also want to further understand both the human and physical effects of a natural hazard in an environment that carries personal meaning to me.

What are landslides?

Landslides, also described as mass movements or slope failure, is the movement of soil, rock and/or organic materials down slopes. The flow can carry between a few cubic meters in volume to over 10 km3 and can move either a little or over 100 km/h . Highland et al. (2008) explain that landslides are classified by the movement which can be a fall, topple, slide, spread, or flow, as well as the material involved, which is distinguished by rock, soil, earth or debris . They also explain how landslides can happen in any type of landscape; however, the type of landslides vary depending on the local and regional conditions. In the case of Canada, specifically the Rocky Mountains, the conditions of the hillslopes depend on the natural local weather patterns, frequency and severity of wildfires, and water movement . Additionally, it is important to note that human activity has an impact on local conditions and on the frequency of landslides. It is also important to take into consideration that humans are also more affected by landslide occurrences since communities are at risk of physical harm or of damage to their homes or businesses.

Causes

Landslides are caused by slope failure, which is driven by both gravity and the characteristics of the land form. They are triggered by both natural and unnatural causes. The Landslide Handbook - A Guide to Understanding Landslides divides the natural causes in three categories: water, seismic activity, and volcanic activity . Water can over-saturate the soil, and reduce slope stability. This is commonly associated with flooding events, which leads to potential undercutting and erosive processes if there is excess water . On the other hand, landslides can also cause flooding if debris from the slide blocks water flow. Seismic activity can be associated with earthquakes and liquefaction processes that affect slope stability in British Columbia. Some examples include the shaking of the ground that reduces the cohesive properties of soil. It can trigger loose debris on slopes to commence a mass movement and cause liquefaction in areas with saturated soils . Lastly, volcanic activity is a very destructive medium of initiating landslides. The volcanic eruption can carry and collect rock, soil, ash and water at high speeds down slope which is extremely dangerous for communities nearby . The natural causes listed above demonstrate the correlation between landslides and other hazardous events where one of the two triggered the reaction of the other. In this case, landslide coverage in the media is documented as an included repercussion of another hazardous event. Thus, landslides may not always get the focus and attention that they should, and people risk not adequately perceiving the danger.

Unnatural causes are linked to human activity. There are many different ways in which we interact with our environment. We are expanding our communities into vulnerable areas and increasing the modification of the natural environment. Some examples from The Landslide Handbook - A Guide to Understanding Landslides include: manipulating drainage patterns, irrigation, reservoirs, excavating, grading and pipes. Additionally, the authors note how removing vegetation reduces resistance forces of the slope stability, as well as, undercutting slopes in order to build homes or roads, for example, which leads to steeper and more vulnerable slopes .

Landslide Risk in Vancouver

Armstrong (1990) highlights Southwestern British Columbia as "the most active earthquake region in Canada" (p.24), which is where the North American and Juan de Fuca plates are the main parts of the subduction zone . The historical geological process that took part in creating British Columbia's topography also highlight the areas of concern. Many steep, rocky slopes and tectonic activity can trigger landscapes.

Vancouver's weather patterns also plays a part in the characteristics of landslides. For instance, the North Shore Mountains in North Vancouver can trigger landslides in the area during large precipitation events. Jakob & Weatherly (2002) explain that the orographic effect has an effect on water flow patterns and the variability of landslide events in the North Shore area, which is characterized by steep cliffs. For instance, orographically enhanced precipitation tends to occur in the fall and winter as an effect of Pacific Cyclones and tends to trigger landslides of morainal and colluvial deposits .

Jakob & Weatherly also list non-climatic landslide triggers that occur in British Columbia. Some of their examples include watershed landuse, natural disturbances like snow avalanches, slope drainage patterns, vegetation characteristics and soil cover .

History of Landslides in British Columbia

Table 1: Historical Information

Historical Landslide Data with Fatalities in British Columbia, 1970-2014

Date	Location	Fatalities	Comments
9/27/1970	Summerland	1	Silt fall
5/4/1971	Boothroyd, Frasier Canyon	3	CNR train derailed by rockfall
3/20/1972	Michel Creek Road, Sparwood	3	Debris flow from coal mine waste dump
7/22/1975	Devastation Glacier	4	Massive rock avalanche
1980/07	Beaver valley	1	Debris avalanche caused by vibrations of a tractor
9/28/1981	Tumbler Ridge	1	Landslide near the Tumbler Ridge coal site
10/28/1981	M Creek	9	Debris flow destroyed bridge
1/16/1982	Brunswick Point	1	Single boulder landing on car
2/11/1983	Alberta Creek	2	Debris flow due to rain flood
11/23/1983	Sunnybrae	2	A large boulder detached from a cliff and destroyed a house
11/10/1989	Maeziadin	1	Rockfall on highway 37A
6/12/1990	Joe Rich	3	Debris avalanche caused by heavy rains
11/23/1990	Dorothy Cove	1	Debris slide associated with forestry activities
9/3/1991	Porteau Cove	1	Rockfall on highway 99
11/19/1993	Alan Reach	1	Debris flow on eastern shore of Alan Reach
3/26/1997	Conrad	2	Highway and railway fill failures
4/16/1997	West Quesnel	5	Shifting soil snapped a gas line and caused an explosion
5/31/1997	Gowan Creek	1	Debris flow caused by heavy rains
1/19/2005	North Vancouver	1	Landslide after heavy rains
5/28/2007	Legate Creek	2	Debris flow buried a truck on Highway 16
5/18/2008	Van Tuyl Creek	1	Debris flow during snow melt following wildfire
7/12/2012	Johnsons Landing	4	Landslide following heavy rains
9/22/2014	Wreck Beach	1	Debris fall
12/22/2014	Lions Bay	1	Rock slide likely due to heavy rains
11/17/2015	Emery Creek north of Hope	1	Debris flow from old logging road, killed driver in logging truck

The data in Table 1 represents fatal landslides in British Columbia from 1970-2015. The data has been reproduced from Open File 7836 by Blais-Stevens et al (2015) called "Historical landslides that have resulted in fatalities in Canada" and is published by Natural Resources Canada . Retrieved from:https://doi.org/10.4095/296421. This table serves to focus on only the events that occurred in British Columbia.

Blais-Stevens et al.'s GSC publication from the Natural Resource Canada site also demonstrates the highest concentration of landslides and number of casualties per event along the west coast of British Columbia compared to the rest of Canada from 1771-2014. Quebec also demonstrates a high number of landslide occurrences and casualties; however, not to the extent of British Columbia. If we were to analyse the causes of the events throughout the last 50 years, as visualized in Table 1, the interactions between humans and the forces at work are evident. In some cases, the debris or rocks destroy man-made infrastructure in their path like roads, railways, bridges, vehicles, and/or homes. In others, the event is triggered by human activity. For instance, there are cases involving the vibrations of the tractor in Beaver Valley, forestry activities in Dorothy Cove, or infrastructure failure. According to my research, it is likely that these events persist if we continue to interact more with areas vulnerable to landslides without attempting mitigation techniques or focusing on community-level understanding of the risks.

Economic Impacts

According to Natural Resources Canada, landslides in Canada cost approximately $200-400 million annually in direct and indirect costs . This demonstrates the high amount of landslide events annually, which is over one thousand in Canada, and their high economic impact. The government of Canada has made funds available for strategies and support in Disaster Mitigation Funding Programs. Among these programs includes a $2 billion investment to support a large-scale infrastructure program to help communities' resilience to natural hazards called the Disaster Mitigation and Adaptation Fund. Additionally, the Federal government has made $24.70 million available to the First Nation Adapt Program to support First Nation Communities related to climate change. The Province of British Columbia has funded $69.5 million towards the resiliency of local governments, First Nations, and communities in emergency situations. In order to also support smaller, rural communities of under 25,000 people in the case of emergency, the Province and federal government are to invest up to $ 95 million in infrastructure in the Canadian Infrastructure Program - Rural and Northern Communities Fund . These programs and more can be found on the official Government of British Columbia website [2].

Costs that affect the population can be described in two ways: direct and indirect. Direct costs cover the repercussion of the event, which include reparations, replacements, and maintenance that have been caused by the hazard . In a recent example, the Big Bar landslide in the Frasier River north of Lillooet was reported in June 2019 and has since been a costly and environmentally destructive incident. CBC News writer Bethany Lindsay reports that the cleanup costs for this site have increased to over $52.5 million as time goes on. Lindsay also highlights the environmental issue of the blocked migration of salmon run routes that are essential for the survival of the species, which is now at risk of extinction. This demonstrates an extreme example of the direct costs associated with a large landslide event. Shuster (1996), conceptualized indirect costs of landslides using some examples like the loss of ecosystem productivity in the case of agriculture and soil richness, reduced real estate values in areas prone to these hazards, cost of mitigation programs, effects on water quality, etc.

Social Impacts

Social impacts are dependent on each isolated hazardous event. The more we interact with areas prone to landslides, the more people are at risk, which is why there have been more fatalities over time. The cost of someone's life impacts their loved ones and the community. Additionally, it affects the risk perception of the community in general. While it is important to be cautious and understand local risks that may threaten your home, it should not hinder your perception of safety or trust in the government.

It is important to also note that not all social groups experience these events similarly. As the population continues to expand into mountainous areas, we should be aware of and mitigate the marginalization of vulnerable groups in areas that may demonstrate environmental threat. Additionally, it is important that the government continues to fund and show support for First Nation communities in Canada in order to ensure that all efforts have been made to protect everyone equally.

Human Impacts & Climate Change

As mentioned previously, human interactions with their environment has changed over time. With urbanization processes, the population is expanding further into nature and land use is changing. For instance, the building of residential areas, transportation routes, geological engineering like dams and more through mountainous areas has been our way of manipulating the environment. However, our interactions also have a history of leading to large-scale hazardous events. Forest fires are primarily caused by lightning or human activity, which happens by smoking or making campfires . The official Government of Canada website also describes the correlation between the higher temperatures from climate change and the frequency and intensity of forest fires. Since forests are drier, fires start easier and the low humidity in the summer makes them more dangerous . Landslides are also common in areas where wildfires have occurred , which puts Canada at an even higher risk of these events if forest fires are longer in duration and more frequent by 2040 as projected . The official Government of Canada website also illustrated the relationship between climate change and changing rainfall patterns, snowmelt and sea level rise in Canada . These changes also impact the frequency of landslides since they demonstrate a correlation . Therefore, it is clear that climate change and the exposure of humans with nature portray a relationship with natural hazards and more fatal outcomes.

Analyzing and Communicating Risk

Use of Geographical Information Systems(GIS) in Monitoring Landslides

GIS stands for a geographical information system that uses computer sciences to gather, analyze, and communicate geographical data with maps . ERSI also explains how GIS can be used to understand patterns and monitor change, which is effective in the case of environmental issues. These technological advances are beneficial for mitigating risk since they are quick and effective . The Landslide Handbook - A Guide to Understanding Landslides explains how map analysis is the first step in understanding landslide events. Maps can demonstrate the bedrock and superficial geology, topology, soils and geomorphology, which is effective in identifying which areas could be more susceptible to an event . It also helps us to access historical data, like through DataBC [3], in order to know where past landslides have occurred. This is useful since landslides are likely to happen in the same areas again .

Communication through maps is also a useful tool to help decision making, for instance, in the case of new infrastructure building. Also, having the maps readily available allows for everyone to have access to knowledge of current and past hazards in their area. Highland et al. identify the important categories of mapping for planners and general public in three criteria. The first is landslide inventories which is the foundation of knowledge available for slope stability, the second is landslide susceptibility which adds the potential of a landslide and the third is landslide hazard maps, which detail the threat to the site .

Resources and Information Available for Communities

Data and maps are available to the public through the official British Columbia website and Government of Canada website. OpenData is available to help with decision making and is useful for those who work with GIS. For instance, DEM files are helpful for visualizing and computing slope values in a given site. Helplines and general information about how to prepare for a landslide is also available for communities [4]. For those who have access to the internet, it is a quick and efficient way to gain information about how to be prepared. However, throughout my research, I noticed that there is more available information about other natural hazards like flooding and forest fires than there is about landslides specifically. Although they can act as triggers to one another, I feel that it's important to focus more research and knowledge about landslides since they can be fatal to humans and animals, and destructive to the environment. This would also demonstrate transparency within the political system if communities felt more protected.

Conclusion / Your Evaluation of the Connections

While there are still many forested and mountainous areas in British Columbia that are not populated, the trend of population growth may one day put more people in harms way. That's why it is important to understand the processes and risks. Additionally, with the impacts of climate change on the earth, we need to mitigate the negative repercussions that affect us and the environment. It is also important to recognize the connectivity between other natural hazards like floods, wildfires, earthquakes and tectonic activity to landslide events.

Since Environment and Sustainability studies and Earth, Ocean and Atmospheric Sciences both focus their studies on the earth, the connections are very easy to make. In analyzing landslides in Vancouver and British Columbia, the geology aspect covers the scientific foundation of the research that was available to me. My degree in Geography enables me to understand and connect this research to community level effects. The research that I found throughout this project enabled me to see how climate change is affecting local environments over time and has led me to ask more critical questions on where research should be allocated next.

References

This Earth Science resource was created by Course:EOSC311.