CHAPTER 3 7 ENT IRONM ENV INFRASTRUCT URE 6 3 4 IETY SOC 5 ECON OM Y Slope movement occurs when soil, rock or snow moves down-slope under the influence of gravity. It can be very slow moving (soil creep) or extremely fast (rockfall, debris flow, avalanche) and can involve a small amount of material, such as a single rock, or whole hillsides. Slope movements can be triggered by undercutting slopes and removing surface vegetation as well as by weather related events such as heavy rainfall or rapid snowmelt. 2 STEP 1: Understanding Slope Movement in Your Community LO 1 S NS TIO CA Slope Movement and Climate Change OPT ION ISSUES It is likely that slope movement has affected your community at some time, as throughout history, numerous incidences of landslides, rock falls and avalanches have occurred in Newfoundland and Labrador. Slope movement can have a significant impact on people and infrastructure; damaging buildings, blocking roads and cutting off access to medical assistance and supplies. Understanding the potential impacts of slope movement is an important part of planning within your community. The figure at left shows incidences of landslide, avalanche and rockfall. Red dots indicate slope movements that resulted in fatalities and yellow dots represent those that resulted in infrastructure damage. Figure Source: Martin Batterson, Geological Survey of Newfoundland and Labrador. Chapter 3 - Slope Movement and Climate Change 3-1 Types of Slope Movement Types of slope movement are distinguished by key characteristics such as the kind of material that is moving and the speed at which it moves. Debris flows - In 1973, a debris flow destroyed four houses in Harbour Breton, NL. Debris Flow: Debris flows involve a mixture of sediment and water and can be extremely fast moving. They are commonly triggered by heavy rainfall or rain-onsnow events. Slump: Slump is a type of landslide where the slope failure surface is on a curve. Material above the failure surface commonly remains intact as it moves downslope. Soil Creep: Soil creep is the slow movement of material downslope, but can result in considerable damage to infrastructure. Rockfall: Rockfalls are commonly the result of freeze-thaw action on bedrock cliffs. Rocks wedged out from bedrock fall rapidly and can cause significant damage to infrastructure and property. Avalanche: Avalanches are another form of rapid slope movement and generally consist of a combination of snow and ice. Avalanches are most commonly triggered by a heavy snowfall over a smooth steep slope (30° to 50°). Aerial photo of the landslide in Daniel's Harbour, NL in April 2007. Photo credit: Martin Batterson 3-2 7 Steps to Assess Climate Change Vulnerability in Your Community Factors Affecting the Vulnerability of an Area to Slope Movement Factors that make an area susceptible to slope movements: • Slope: Slope movement is more likely to occur on steeper terrain, and in some cases, boulders may roll away from the base of a steep slope. • Weather: Many slope movements occur after a heavy rainfall, during rain-onsnow events or during periods of rapid snowmelt. This is due to either the added weight of water in the soil or the erosion of the supporting soil base. In the winter, freezing rain followed by heavy snowfall may lead to an avalanche on steep slopes. Photo credit: Pat Careen Slump - Point Lance, NL. • Bedrock geology: Rock types that are greatly jointed or fractured are more susceptible to weathering than rocks with no joints or fractures. Weathered rocks are more likely to become unstable and move downslope . • Surficial geology: Cliffs composed of loose material such as sand and gravel erode more quickly than bedrock cliffs. Also, since thick soils can absorb more water than thin soils, steep slopes covered with thin soil are more susceptible to slope failure following periods of heavy rainfall or rapid snowmelt. • Past slope movement: Slope movement is more likely to occur in areas where it has previously occurred. • Human impacts: Development near the top of a slope can affect drainage and the overall stability of that slope if preventative measures are not put in place. Removing vegetation from a steep slope or digging up the lower part of a slope, thereby creating a steeper grade, are also examples of how human activity can lead to slope movement. • Sediment: The type of sediment (silt, sand, gravel, till) will influence slope stability. Sand and gravel can be easily eroded whereas other sediment types erode more slowly. Soil Creep - Quidi Vidi, St. John’s, NL Photo credit: Norm Catto Chapter 3 - Slope Movement and Climate Change 3-3 Please answer the following questions related to slope movement in your community. How have slope movements impacted your community? Photo credit: Government of Newfoundland and Labrador Retaining wall built to prevent slope movement in Springdale, NL. What caused these slope movements? Slope Movement in the Future Many areas will likely experience an increase in the occurrence of slope movement as climate patterns continue to change. Increased amounts of precipitation, extended periods of heavy rainfall, rapid snowmelt and heavy snowfall during the winter will all contribute to the increased likelihood of slope movement. Through careful planning and development, your community may be able to reduce the risk of slope movement occurring and diminish the impact on your community if it does occur. Please note that options to reduce the likelihood of slope movement occurring are discussed at the end of this chapter. 3-4 7 Steps to Assess Climate Change Vulnerability in Your Community Based on future climate projections outlined in the introduction, do you think slope movements will happen more often in your community? Place a check mark beside each question that you can answer with ‘yes.’ To address questions that you answered with ‘no,’ please refer to the Resource Guide at the back of this workbook for help. Final Checklist Have you identified how slope movement has impacted your community? Have you identified what caused slope movement in your community? Have you assessed whether slope movement might occur more often in the future? Slope Movement. Irishtown-Summerside, NL. Photo credit: Kimberly Bittermann Chapter 3 - Slope Movement and Climate Change 3-5 LO 1 S ENT IRONM ENV 6 5 ECON OM Y Location Assessment 4 Things to consider: • Planning and zoning • Development • Slope grade • Vegetation • Drainage • Rock type • Sediment type • Snow accumulation • Other IETY SOC • Locate the areas within your community that are at risk of slope movement. INFRASTRUCT URE This step will help you: 3 To complete steps 2 - 7, you will need a map of your community. Please refer to the Resource Guide at the back of the workbook to find out how to obtain this map. 2 7 OPT ION ISSUES NS TIO CA STEP 2: Identifying Locations Affected by Slope Movement in Your Community Here you will determine where slope movements have occurred and which areas of your community could be at risk. Certain areas of your community may be more vulnerable to slope movement such as steep slopes or cliffs with infrastructure built at the base or on the top. Slope failure is causing this fence to slump downwards Photo credit: Nicole Renaud Chapter 3 - Slope Movement and Climate Change 3-7 Case Study: Upper Island Cove, NL Photo credit: Government of Newfoundland and Labrador Rockfall in Upper Island Cove, NL. On February 14, 1999, an eight tonne rock fell from a hill behind Upper Island Cove in Conception Bay, NL. The boulder rolled down the approximately 100m slope, striking and damaging a house, an aluminum shed and a vehicle. The boulder hit the bedroom and chimney of the home, knocking the bed across the room but thankfully leaving the occupant uninjured. Bricks from the chimney damaged another car in a neighbouring driveway. Approximately 15 homes were evacuated, with over 40 people displaced, as the area was assessed for any further danger. This incident was well documented by government geologists and private consultants and it was found that the rock came from a wedge type failure. The rock travelled down a direct path, bouncing and splitting in two at the base of the slope. A follow-up study identified other loose blocks that required stabilization and suggested that the risk of another rock fall was high. In response to this hazard, protective measures were installed during the summer of 1999. Please answer the following questions related to slope movement in your community. What areas of your community have been affected by slope movement? Have some areas been more affected than others? 3-8 7 Steps to Assess Climate Change Vulnerability in Your Community Use Table 1 below to identify factors that have influenced where slope movement has occurred in your community. Table 1: Factors influencing slope movement in your community Factor Shape of the landscape Drainage Rock type Sediment type Vegetation Check box if factor has influenced slope Comments or movement information sources o o o o o Planning, zoning and land uses o Other o Community Mapping Do you know what areas in your community are vulnerable to slope movement? If yes, please identify these areas by drawing on your map. If you are unsure, there are resources available to help you determine these areas including aerial images and topographic maps. Aerial photographs from various years are valuable as they can illustrate changes in landscape over a period of time. In addition, knowledge from community members may be helpful to determine locations of slope movements that were not publicly recorded either because they happened a long time ago or because of their small size. Newspapers may have reports of recent or large events; as well, the Geological Survey of Newfoundland and Labrador maintains a database of reported events in the province. Information on how to obtain the above-mentioned resources is available in the Resource Guide at the back of the workbook. Chapter 3 - Slope Movement and Climate Change 3-9 Do you expect that the areas in your community affected by slope movement could change in the future? Final Checklist Have you identified where slope movements have occurred? Have you considered where slope movements might occur in the future? Community mapping can help assess vulnerabilities and identify areas that have been impacted by slope movement. The completed map can provide guidance on how to minimize the impacts of future events. Photo credit: Kimberly Bittermann 3-10 7 Steps to Assess Climate Change Vulnerability in Your Community 6 4 5 ECON OM Y • Locate identified infrastructure; and IETY SOC • Identify key infrastructure in your community; INFRASTRUCT URE 3 ENT IRONM ENV 2 This step will help you: LO 1 S 7 OPT ION ISSUES NS TIO CA STEP 3: Identifying Facilities and Infrastructure Affected by Slope Movement in Your Community • Better understand the potential impact of slope movement on infrastructure. Things to consider: • Police and fire stations • Hospitals and nursing homes • Water supply and treatment • Sewage and wastewater • Power sources • Roads, bridges, culverts and trails • Schools • Community and heritage buildings • Other Facilities and Infrastructure Affected Here you will identify the location and characteristics of key infrastructure so you can determine where to focus your adaptation efforts. Rockfall on Pitts Memorial Drive in St. John’s, NL, April 2007. There were no injuries but the road was closed for several hours. Photo credit: Department of Natural Resources, NL Chapter 3 - Slope Movement and Climate Change 3-11 It is important to know the location of infrastructure that may be affected by slope movement, as well as characteristics such as its age and state of repair. You should also determine if slope movement has damaged the infrastructure in the past. As you go through this step, keep these questions in mind: • What key infrastructure in your community would be vulnerable to damage from slope movement? • Is any infrastructure in need of repair, replacement or upgrades? • Does the state of this infrastructure make damage from slope movement more likely? • Who should be involved to address these concerns? Examples of key infrastructure include: police and fire stations; hospitals and nursing homes; water supply and treatment stations; sewage and wastewater systems; power sources; roads, bridges, and culverts; trails; schools, churches, heritage structures, community centres and other community buildings. Please fill in Table 2 with information on infrastructure in your community Table 2: Inventory of Community Infrastructure Infrastructure Could it be impacted by slope movement? If yes, how? Who is responsible? (name, email, phone number) *A full size version of this table is available in the Resource Guide. 3-12 7 Steps to Assess Climate Change Vulnerability in Your Community Comments (age, level of maintenance, past problems, material used) Are you aware of any unstable slopes in your community that may need stabilization? Point Verde, 1999 Have any buildings in your community been damaged by slope movement? If yes, list examples. Point Verde, 2003 Is infrastructure development planned for areas with steep slopes? Are you aware of any infrastructure that is currently not at risk but may be at risk in the future? Point Verde, 2005 Point Verde, 2011. Structure now on beach. Chapter 3 - Slope Movement and Climate Change 3-13 Final Checklist Have you identified infrastructure that has been impacted by slope movement? Have you identified infrastructure that may be at risk in the future? This photo shows the remains of a house that was destroyed in an avalanche at Tilt Cove, NL in March 1912. Photo credit: Family of the late Dr. O.V. Smith; Sheida, Babs and Maureen Mackinnon 3-14 7 Steps to Assess Climate Change Vulnerability in Your Community 7 OPT ION LO 1 S 6 4 5 ECON OM Y • Consider social or cultural impacts of slope movement; and IETY SOC • Determine individuals and groups most impacted by slope movement and where they live; INFRASTRUCT URE 3 ENT IRONM ENV 2 This step will help you: ISSUES NS TIO CA STEP 4: Identifying Individuals and Groups Most Affected by Slope Movement in Your Community and Those Able to Assist • Determine who can help. Things to consider: • Elders and youth • Single parent households • Special needs • Literacy levels • Emergency services • Volunteer and community groups • Recreation and cultural activities • Isolated locations • Other Social Assessment Here you will identify individuals and groups most likely to be impacted by slope movement, where they live and who can assist. Slope movement can be devastating to communities if it results in injuries and damage to homes and infrastructure. It is important to recognize that some members of your community may not be able to respond and react to slope movement in the same manner as others. Understanding who may be most affected can help target important areas for investment and set priorities for planning. Volunteer groups and other community support may be a resource you can draw upon to help residents prepare for and respond to slope movement. Daniel's Harbour, NL. Individuals and groups living along this coast have been impacted by slope movement. Photo credit: Fire and Emergency Services, NL Chapter 3 - Slope Movement and Climate Change 3-15 Case Study: The Battery, St. John’s, NL Photo credit: Government of Newfoundland and Labrador St. John’s Battery, NL On the night of February 16, 1959, there were 200 km/hr winds and 55 cm of snow in St. John's. At 1:05 am residents in the Outer Battery heard a sound described as a loud clap of thunder. An avalanche struck 2 houses, sweeping them downslope and into the rear of two other houses. Rescuers were on the scene almost immediately to help search for the fourteen people swept down the slope by the avalanche. Over 50 residents dug through debris and quickly rescued a man, his wife and child as well as 3 children from the other family. One of the children, a two year old girl, was swept 60 m downslope and was rescued by a resident who saw her through his window. After two hours of digging they rescued a 16 year old girl and after 10 hours her friend was rescued. Unfortunately, five of the residents could not be saved. Since 1959, no serious incidents have occurred in the Battery, although residents have reported minor rockfalls and avalanches. Due to development of the historic site as well as increased activity and foot traffic in the area, there have been concerns about rockfalls. The Newfoundland and Labrador Geological Survey contacted the City of St. John's, who was already concerned about the rockfall hazard, and told them of the history of avalanches in the area. The Geological Survey recommended that the Canadian Avalanche Association visit the site; which they did. They recommended the fencing be designed for avalanches as well as rockfalls. In addition, the Historic Site commissioned two reports in 1980 and 1992 which identified a rockfall hazard and recommended remedial work. New warning signs were placed at North Head Trail to divert people away from the slopes and protective fences were constructed in 1998, but have not yet been tested by a significant rockfall or avalanche. Protective fencing in the Battery, near St. John's, NL Photo credit: Geological Survey of Newfoundland and Labrador 3-16 7 Steps to Assess Climate Change Vulnerability in Your Community Please answer the following questions related to the social implications of slope movement. List individuals and groups who have been affected by slope movement in your community. Are there obstacles to residents receiving help if there is an incidence of slope movement (communication, transportation)? Does your community have an up-to-date emergency plan? o Yes o No If yes, does this plan address potential barriers to people receiving help if there is an incidence of slope movement? If no, do you have the necessary resources to create an emergency plan? Chapter 3 - Slope Movement and Climate Change 3-17 Are there important heritage or recreational areas that have been affected by slope movement in the past or may be affected in the future? Are there any other ways that local lifestyle or cultures have been or may be impacted by slope movement? Please note that it is extremely important to use caution when slope movement occurs as secondary slides are common and can injure those responding to the first slide. There may be individuals and groups, both within your community and outside, with first aid training, emergency response experience or amateur radio training who could help in the event of a slope movement. It is important to have up-todate contact information for these individuals and groups in case of an emergency. Please note that it is extremely important to use caution when slope movement occurs as secondary slides are common and can injure those responding to the first slide. Please fill in the Table 3 on the next page with information on agencies or individuals that could help in the event of a major slope movement (or refer to your emergency plan if an up-to-date list already exists). 3-18 7 Steps to Assess Climate Change Vulnerability in Your Community Table 3: Community Contact List Agency/Person Business phone # Home phone # Comments/Role *A full size version of this table is available in the Resource Guide. There are other resources that may be available in your community and could be useful in the event of a slope movement. A few examples are listed in Table 4. Certain people in your community may have the ability, experience or resources to help others cope with the impacts of slope movement. Please complete the table and add any other resources that could be helpful if slope movement occurs. Table 4: Inventory of Community Resources Resources Owner (s) Phone # Comments Large shovels or other rescue tools Backhoe Generator (Note power output) Other (satellite phone, radio) *A full size version of this table is available in the Resource Guide. Chapter 3 - Slope Movement and Climate Change 3-19 Community Mapping By drawing on the map you started in Step 2, identify the areas in your community where people most vulnerable to slope movement live, as well as, the location of community services, volunteer groups or others who can help in case of a major event. Final Checklist Have you identified where people most vulnerable to slope movement live? Have you identified who can help during an emergency? Have you considered the potential social or cultural impacts of slope movement on your community? 7 Steps to Assess Climate Change Vulnerability in Your Community LO 1 S ENT IRONM ENV 6 5 ECON OM Y Economic Assessment 4 • How slope movement could affect the financial resources of your community. IETY SOC • How slope movement may impact these sectors; and Things to consider: • Fishery • Forestry • Tourism • Food and agriculture • Construction • Manufacturing • Transportation • Retail and services • Budget • Insurance costs • Other 3 • Your most important economic sectors; INFRASTRUCT URE This step will help you determine: 2 7 OPT ION ISSUES NS TIO CA STEP 5: Identifying Economic Consequences of Slope Movement on Your Community Here you will identify your community’s key economic sectors and financial resources and how they could be affected by slope movement. Slope movement can have serious economic consequences on communities, affecting local businesses and employment, as well as, damaging the infrastructure required for the local economy. It is important to consider the financial resources required to deal with damages caused by slope movement. . Slope movement can result in major economic loss by damaging infrastructure as well as utility poles, fences and other structures. A protective wall was built along the roadside to deal with slope movement at Frenchman's Cove, Humber Arm South, NL. Photo credit: Norm Catto Chapter 3 - Slope Movement and Climate Change 3-21 Please answer the following questions related to slope movement and your economy. What businesses, services and industries contribute most to your community’s economy? Has slope movement impacted them in the past? If yes, how? What businesses, services and industries are expected to be most important in the future? How could slope movement impact them in the future? 3-22 7 Steps to Assess Climate Change Vulnerability in Your Community If applicable, what will happen to your tax base if these businesses, services or industries are impacted by slope movement? Can you estimate the costs associated with addressing slope movement in your community? What revenue sources exist to cover these costs? What costs would have to be covered by your community? Photo credit: Kimberly Bittermann Destabilized bank in Flat Bay, NL. Community Mapping By drawing on the map you started in Step 2, identify locations where key economic activities take place. This can direct and guide your decisions related to slope movement. Final Checklist Have you identified where your key economic activities take place? Have you determined if they will be impacted by slope movement? Have you attempted to calculate the financial costs associated with slope movement in your community and how you would cover these costs? Chapter 3 - Slope Movement and Climate Change 3-23 LO 1 S ENT IRONM ENV 6 5 ECON OM Y Environmental Assessment 4 Things to consider: • Hazardous and toxic sites • Oil facilities • Ports • Landfills • Tailings ponds • Pests and diseases • Fish and wildlife • Parks and protected areas • Sensitive habitats • Other IETY SOC • Understand how slope movement may affect important species or natural areas. 3 • Determine if slope movement could cause other environmental problems; and INFRASTRUCT URE This step will help you: 2 7 OPT ION ISSUES NS TIO CA STEP 6: Identifying Environmental Impacts Caused by Slope Movement in Your Community Here you will consider how slope movement may affect the natural environment and identify sensitive areas that may be a planning priority for your community. This step will help you identify environmentally sensitive areas in your community that could be affected by slope failure. For example, a landslide can remove hillside vegetation and fill nearby streams with debris, thereby decreasing water quality for plant and animal habitats. By identifying these sensitive areas, you may be able to find ways to minimize negative impacts. Beach habitat is important to many species, including the Piping Plover. Photo credit: Kimberly Bittermann Chapter 3 - Slope Movement and Climate Change 3-25 Please answer the following questions related to the environmental impacts of slope movement. Could slope movement cause environmental problems in your community? If yes, please explain. Are there endangered species or protected habitats in your community that may be threatened by slope movement? Are there concentrations of hazardous waste in your community? o Yes o No If yes, are they stored safely? o Yes o No Could slope movement increase the risk of hazardous waste being released into the local environment? o Yes o No If yes, briefly describe how slope movement could increase the risk of hazardous waste release. Do you have an environmental protection plan in place? o Yes o No If not, you may want to consider developing one. 3-26 7 Steps to Assess Climate Change Vulnerability in Your Community Community Mapping By drawing on the map you started in Step 2, identify environmentally sensitive areas in your community, as well as, other areas where slope movement could have environmental impacts. Final Checklist Have you identified environmentally sensitive areas in your community? Have you assessed how these areas might be affected by slope movement? Have you considered how slope movement might affect your local environment and fish and wildlife species? Chapter 3 - Slope Movement and Climate Change Photo credit: Department of Environment and Conservation – Government of Newfoundland and Labrador 3-27 LO 1 S ENT IRONM ENV 6 5 ECON OM Y • • • • • • Adaptation Options 4 Things to consider: Infrastructure Technology Financial resources Human resources Policy and planning Emergency measures • Education and awareness • Other IETY SOC • Identify ways to reduce the negative impacts of slope movement. 3 • Evaluate how your community has dealt with slope movement in the past; and INFRASTRUCT URE This step will help you: 2 7 OPT ION ISSUES NS TIO CA STEP 7: Identifying Adaptation Options for Your Community Here you will identify actions to deal with the impacts of slope movement in your community. This step will help you identify adaptation options to reduce the impacts of slope movement. It may also help you determine the best solutions for your community while enhancing your ability to cope with future issues. The community mapping exercises that you have completed in this chapter will illustrate where slope movements could cause the greatest problems for your community. Key adaptation concerns and priority areas for planning may become apparent once you have had a chance to discuss the information you have collected. Subsequent slope failure affected homes and businesses in Daniel's Harbour, NL. Photo credit: Fire and Emergency Services, NL Chapter 3 - Slope Movement and Climate Change 3-29 Considering all of the information in steps 1 to 6, list the main slope movement concerns for your community. Photo credit: Geological Survey of Newfoundland and Labrador Fencing in Upper Island Cove, NL Which past actions or measures have been successful in reducing the impacts of slope movement in your community? Please list. What actions or measures were most effective? What adaptation options would your community like to try? What are the barriers to trying these options? Are there ways to overcome these barriers? 3-30 7 Steps to Assess Climate Change Vulnerability in Your Community Potential Options Slope movement impacts can be addressed in a number of ways. Six potential options are explained below and you will find more examples, in the form of case studies, in the Resource Guide at the back of the workbook. 1. Infrastructure: Adaptation options that may help decrease the likelihood and severity of slope movement include: installing drainage to direct water away from unstable slopes; building retaining walls at the base of slopes prone to slope failure; planting vegetation, such as grass and trees, to stabilize slopes; and installing proper fencing in areas prone to rockfalls and avalanches. 2. Monitoring: Monitoring for the purposes of predicting slope failure is difficult and unreliable. However, monitoring environmental variables such as precipitation and snow accumulation in areas where there has been a history of slope failure may provide useful information on slope movement in the future. 3. Education: Education is an important way to build awareness and encourage caution in areas that are vulnerable to slope movement. Also, encouraging awareness of what to do in the event of a slope movement can help people better prepare for and deal with the event if it does occur. 4. Preventative measures: Vegetation is important in providing strength to a slope so communities should ensure that trees and other vegetation are not removed from steep slopes. Similarly, beaches protect inland areas from flooding and erosion so communities should safeguard against material being removed from beaches. 5. Preventative zoning and permitting: Planning and development should include an assessment of areas that are vulnerable to slope movement. New structures should not be built close to cliff edges or below cliffs prone to rockfall and construction should not dig into the base of slopes. Discouraging development in areas that are prone to slope movement is the best way of ensuring the safety of people and the protection of infrastructure. 6. Emergency measures: Having an up-to-date emergency plan is critical in the event of a major slope failure. Chapter 3 - Slope Movement and Climate Change 3-31 Considering the above, please identify new adaptation options that may help address slope movement concerns in your community. Please list the adaptation options you would like to pursue to address slope movement in your community: 1. 2. 3. 4. 5. Not all of these options will have the same cost or require the same time, resources or personnel. Certain solutions will be more effective and have long-lasting impacts. In the conclusion of this workbook you can further consider the benefits and feasibility of pursuing each of these options and develop action plans for implementation. 3-32 7 Steps to Assess Climate Change Vulnerability in Your Community