hazard risk assessmentmovement of the mass is characterized by flowage regardless of whether it is...

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Hazard Risk Assessment Hydrological (related to water and snow)

Avalanches - Natural and Human Caused Debris Avalanches, Debris Flows and Torrents Drought - Natural and Human Caused Flash Floods Ice Jam Floods Local Floods Rain Storm Floods Snow Melt Floods Glaciers Iceflows, Icebergs, Ice Islands and Sea Ice Lake Outbursts

Hydrological This section discusses hazards that are related to water or snow. This includes: Avalanches, Debris Avalanches, Debris Flows and Torrents, Drought, Flash Floods, Local Floods, Rain Storm Floods, Ice Jam Floods, Snow Melt Floods, Glaciers, Iceflows, Icebergs, Ice Islands and Sea Ice, Lake Outburst. Resources are available to assist you in completing this assessment in the Risk Assessment Resources section. Many of them are both naturally caused and caused by humans.

Risk Rating There are eleven hydrological hazards and many of them are both naturally caused and caused by humans. When you come developing resilience strategies for these hazards it is important to understand where the primary cause for the hazard lies.

Avalanches

Definition An avalanche is a movement of snow and ice in response to the force of gravity down an incline.

RDRP: Hazard Risk Assessment

2 HYDROLOGICAL

Discussion Avalanches can be divided into three zones. The starting zone is defined as the area from which avalanche release is initiated. The second component, the avalanche track, is the portion of the path between the bottom of the starting zone and the top of the runout zone. The runout zone is the area at the bottom of the path in which avalanches usually stop and is sometimes referred to as the ‘area of deposit’. Avalanches are rated from small (less than 0.3 metres deposited) to climax (greater than 3.0 metres deposited over 150 metre wide track. Factors such as the type or nature of snow, ambient temperature and wind conditions are critical in avalanche potential. Conditions such as dense, wet snow falling on dry, loosely packed snow may give rise to an avalanche.

It Happened Here… On January 1, 1999, an avalanche crashed into a school gym in the remote northern Quebec community of Kangiqsualujjuaq (population 650). The event led to 9 deaths, 25 injuries and exposed approximately 400 people to 100 km/h winds and -20°C weather1. In December 1996 Following a heavy snowfall, the Fraser Canyon was hit with over 500 avalanches between Boston Bar (population 478) and Yale. Hundreds of people were stranded and many communities were cut-off from supplies. The Provincial Emergency Program airlifted food to the affected communities.2

Avalanche 3 4 5- Natural

Hazard Rating High Risk Low Risk

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FACTORS

**Avalanches generally occur in the same place year after year. Have avalanches previously occurred in or near to your community?

Avalanches occur in mountainous terrain, generally on slopes with an incline between 250 and 550 degrees. Is your community located near avalanche-prone slopes?

Roads and highways can be at risk of avalanche. If your community is located in or near to avalanche terrain, is there a lack of avalanche control measures?

Avalanches occur in areas with deep snow cover. Does your community receive large amounts of snow in the winter?

Increased snowmelt caused by rain or rapid warming can increase the likelihood of avalanche. Does your region receive rain-on-snow events or periods of rapid warming in the winter?

Figure 1 Avalanche Zones 1


HYDROLOGICAL 3

Avalanche 6 7 8 9 10- Human-caused


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FACTORS

**Avalanches generally occur in the same place year after year. Have avalanches caused by humans previously occurred in or near to your community?

Avalanches occur in mountainous terrain, generally on slopes with an incline between 250 and 550 degrees. Is your community located near avalanche-prone slopes?

If your community is located in or near to avalanche terrain, do you lack effective avalanche control measures or avalanche inspections?

Increased snowmelt caused by rain or rapid warming can increase the likelihood of avalanche. Is your community in mountainous terrain and does your region receive rain-on-snow events or periods of rapid warming in the winter?

Backcountry skiers and snowmobilers are at risk of causing avalanches. Are these activities popular in or around your community?

Scientists note that changes to winter snowfalls amounts and rapid warming and refreezing can occur. Has your community experienced such increases?

Debris Avalanches, Debris Flows and Torrents

Definition Debris flows are a form of rapid mass movement in which loose soil, rocks and organic matter, combined with air and water, form a slurry that then flows down-slope11. Debris avalanches are terrifying avalanches of mud, rock, brush, trees and other debris loosened and propelled by torrential rains - very rapid to extremely rapid debris flows. The term "debris avalanche" is also used to describe the transformation of a volcano slope into a "sudden and very rapid flowage of an incoherent, unsorted mixture of rock and soil material. Movement of the mass is characterized by flowage regardless of whether it is wet or dry"12. Mudflows are special forms of debris flows that are mainly made of the smallest mud and silt particles. Extremely heavy rain, or a sudden thaw can trigger these types of flows. In the case of lahars, a sudden thaw of mountain snow due to a volcanic eruption can send a torrent of mud, ash, and hot water down the slope of the volcano and over neighboring towns.

Discussion Debris avalanches are triggered by intense autumn and winter rainstorms, when water infiltrates and saturates the surficial layer of weathered colluvium. They may temporarily block gullies swollen with runoff water, thus changing into rapidly moving debris flows13. Debris avalanches, commonly originating in shallow drainage depressions, begin as large masses that suddenly break away from the land form, leaving well-marked, semi-circular head scarps14. The high speeds are often indicated by the presence of gravel and boulders deeply imbedded in trees along the area.


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Debris flows or slides are often smaller in area and wider in scope as compared to debris avalanches; the debris slide failure surface often occurring within the upper soil mantle. Today, debris torrents are often due to poor logging practices: log jams are created on mountainous streams and then burst during a storm.15 Landslides and debris torrents in unstable mountainous areas of Canada will become more common as winter precipitation rises,

permafrost degrades and glaciers retreat. Water quality, fish and wildlife habitat, as well as roads and other structures will be at increased risk16.

It Happened Here… Debris avalanches affected the small town of Port Alice, British Columbia (population 821) in 1975. The avalanches moved down steep gullies and out onto the fan on which the town of Port Alice was built. There were no fatalities17. Approximately 30 km east of Terrace, BC on June 8, 1992 failure at approximately 1:00 am and is described as a complex rock avalanche-debris flow. The debris traveled for more than 4.5 km descending about 1250 m. The slide triggered a forest fire, ruptured a gas pipeline, dammed the Zymoetz River, flooded a Forest Service road, and destroyed a bridge.18

Debris Avalanches, Debris Flows and Torrents 19 20 21 22 23- Natural


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Debris flows do not occur in flat areas. If your community and the areas in close proximity to it are flat you can safely state that it is “Not Applicable.”

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FACTORS

**Debris torrents and debris flows are most likely to occur where they have occurred in the past. Has your community experienced debris flows?

Debris torrents and debris flows are likely to occur under similar conditions to landslides. Is your community susceptible to some or all of the risk indicators for landslides? (see the section on Landslides)

**Debris flows are most likely to occur when loose (unconsolidated) soil and other ground material becomes saturated with water. Is your community located on steep slopes which experience intense periods of rain and/or rapid snowmelt? Is flooding likely or possible in your community? (see the section on Flooding)

Debris flows often occur on slopes with eroded pathways down the (channeled) slope. Is there evidence of channeling on slopes in or near to your community?

Debris flows can occur if there is a volcanic eruption which suddenly melts large quantities of snow and ice. Is your community near a volcano with snow and ice at the peak?

Debris flows can be triggered on the site of a previous landslide. Is your community near a previous landslide?

Figure 2 Debris Slide1


HYDROLOGICAL 5

Debris Avalanches, Debris Flows and Torrents 24 25 26 27 28 29 30 31-32 Human-caused


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FACTORS

**Debris flows are most likely to occur where they have occurred in the past. Have there been previous debris flow events in or near to your community? Are there slopes in or near to your community that are known to be unstable?

Debris flows may occur if there are large forested areas which have been logged or where vegetation has been burned away along a steep slope. Is your community near a recently logged slope or where there has recently been a major fire?

Construction activity on or adjacent to slide-susceptible slopes can increase the likelihood of debris flows. Does your community allow construction on slide-susceptible slopes?

Scientists have observed that with increased number of rainstorms and increased amounts of rain the likelihood of debris flows could increase. Has your community experienced increased numbers of rainstorms and increased rainfall?

Drought

Definition Drought results from an abnormal water deficiency – or simply put, abnormally low water levels or availability. While drought is often measured in terms of water deficiency, it manifests itself in crop failures, dust storms, polluted water supplies and distressed economic and ecological systems.

Discussion Droughts are usually due to natural causes, but are exacerbated by growing demands, urbanization and other human conditions. While usually considered in the context of agriculture, many other resources and commercial activities are affected. Forest fires are largely the product of drought. Decreased water levels in lakes and streams can greatly penalize inland navigation, fish production, recreation and hydropower generation33. Each drought is different, although many droughts appear cyclic in nature, and there may be many years between droughts. In arid regions of the world, which occupy over one-third of the world's land, droughts may appear to be endless34. But drought occurs in every type of climate; the intensity, duration and area of impact greatly fluctuating from locality to locality. While the primary cause of drought is variations in the climate which produce less precipitation than expected, there are many other underlying factors which need to be considered. The main causal factors to be considered are degradation of the land, climate changes and increased water usage.


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It Happened Here… The spring of 2009 was the driest in 50 years for agriculture producers in the Canadian Prairies. Drought affected the majority of southern Alberta and Saskatchewan, including the small town of Balgonie (population 1,384) in Saskatchewan. Saskatoon, near Balgonie, had less than 25% of the average precipitation during March, April and May, which was the driest since 189235. In 1992, the Canadian Prairies experienced drought causing $575,352,000 in damages. Livestock yields were low in northern Alberta due to dry conditions; severe and widespread surface water droughts were reported on the Prairies. It was the coldest July since 1884. One of the associated causes with the increasing intensity of drought in the Prairies is climate change, linked to greenhouse gas emissions generated by humans. The small livestock farming town of Eaglesham, Alberta (population 159) was one of the many affected36.

Drought37,38 - Natural


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FACTORS

**Are there areas in your community that receive below average rainfall each year?

**Are there areas in your community that receive constant and/or frequent dry weather?

Are there areas in your community with frequent winds coming from land (as opposed to the ocean)? This indicates low water vapor content in the air.

Are there areas in your community where there is relatively little silt in the soil? Silt holds water and can help prevent drought.

Scientists have observed that in some regions in Canada there have been reduced levels of rainfall over the summer which has led to declines in summer soil-moisture levels which could result in significant declines in summer and autumn runoff in these regions and lead to drought conditions. Has your community experienced decreases in summer rainfalls?

Drought39,4041,42 4344-Human-caused


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FACTORS

Are there areas in your community where reservoir (aquifers, groundwater, fresh water) levels are dropping?

Are there areas in your community that use excessive irrigation?


HYDROLOGICAL 7

Are there areas in your community that have been over-farmed, excessively irrigated, deforested, or eroded? These factors can also prevent the land from capturing and holding water.

Are there areas in your community in which vegetation cover has been lost over time due to human activities? This increases likelihood of wind erosion and drought.

Is your community located on the Canadian Prairies? This region of Canada is at higher risk of drought because of agriculture dependence and the primary water supply is surface water (as opposed to an aquifer, for example).

Scientists have observed that in some regions in Canada there have been reduced levels of rainfall over the summer which has led to declines in summer soil-moisture levels which could result in significant declines in summer and autumn runoff in these regions and lead to drought conditions. Has your community experienced decreases in summer rainfalls?

Flash Floods

Definition A flood caused by heavy or excessive rainfall in a short period of time, generally less than 6 hours. A flash flood rises rapidly, often with little or no warning. Flash flood may occur in rural or urban settings.

Discussion Many things can cause a flash flood. Generally they are the result of heavy rainfall concentrated over one area. Most flash flooding is caused by slow-moving thunderstorms, thunderstorms that repeatedly move over the same area, or heavy rains from hurricanes and tropical storms45.

It Happened Here… The March 2009 Red River flood affected the Winnipeg area of Manitoba, including the small town of Morris (population 1700). The flash flood resulted from many factors, such as water-logged and frozen ground, spring snowmelt, rain storms, snowstorms and relatively level ground. Numerous communities near Winnipeg were evacuated. Total insured losses exceeded $40M46. On August 4th, 2003, in Tingwick (population 1,339), 139 millimeters of rain fell in two hours, including about 80 millimeters of rain in one hour alone. This storm caused numerous rivers and small streams to overflow. As a result of the severe flooding riverbank erosion there was damage to bridges, roads, buildings, homes, and crops. The flooding forced more than 500 residents to abandon their homes temporarily and resulted in the evacuation of 150 people. Fortunately, no deaths or injuries were reported; however, seven bridges were washed out. Damages to roads and bridges were estimated between $5 and $7 million within the municipality of Tingwick alone.47


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Flash Floods 48,49,50,51- Natural


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FACTORS

**Are there areas in your community with a water basin prone to runoff (small capacity, narrow shape, steep slope, lack of vegetation on surrounding land, and surrounding surfaces do not absorb water)?

Are there areas in your community near a body of water with a high average annual flow rate?

Are there areas in your community with heavy annual rainfall (especially if in short periods of time)?

**Are there areas in your community on or near flood plains (low lying, flat ground) that have received long and intense periods of rainfall in the past?

Are there areas in your community with riverbank erosion or on an area prone to landslides? (see the section on Landslides)

Ice Jam Floods

Definition Ice jams occur during freeze-up of rivers in winter or the break-up of winter ice cover in early spring. During the cold months, a layer of ice develops on river surfaces, leaving water to flow beneath. This ice cover can be thin because of spring melting or insufficient winter freezing. If enough water is supplied to the river (e.g., from snowmelt or rainfall), pressure exerted from underneath may be sufficient to break the ice cover. If so, the ice pack then flows downstream. These chunks of ice may then become lodged where the flow is constricted, obstructed or slowed. They may converge at channel bends and bridge piers where rivers bifurcate around islands, or become more shallow and have gentle gradients. When significant amounts of ice build-up, they may block the flow of water. As water collects in the newly formed reservoir behind the jam, areas upstream may begin to flood. If the icejam breaks under the pressure of the upstream water, large volumes of water may flood downstream locations52.

Discussion The magnitude of ice jam floods is a function of the amount of water flowing through the river and the size of the ice jam obstruction.Flooding from ice jams tends to be localized since it is dependent directly on the formation of an ice jam, and the tendency for an ice jam to form at any given location along a river is variable. Ice jam formations along a river is promoted by the presence of local sections of intact ice cover during break-up, and/or local channel characteristics (e.g., channel shoaling, variation in channel width, channel splitting by islands or bars, and sharp bends). However, ice jams can also form behind bridges and other structures that constrict a channel53.


HYDROLOGICAL 9

It Happened Here… On January 18, 2006, a 6km long ice jam rose water levels in the Saint John River of New Brunswick, threatening to lift a historic 105-year-old wooden bridge off its piers in the small town of Hartland (population 947); no deaths or injuries were reported54. The town of Badger (population 813) was evacuated February 15, 2003 after ice-jams in the Exploits, Red Indian and Badger Rivers caused flooding. The flood waters reached levels marked as within the predicted 100-year flood on flood hazard maps. Property damage was estimated as being in the millions of dollars; 1200 people were evacuated.55

Ice Jam Floods 56,57 - Natural


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FACTORS

Are there areas in your community near a river that freeze over with thick, strong ice during the winter?

Are there areas in your community with a large amount of rapid runoff as well as typically sunny weather in the spring?

Are there areas in your community in which the spring following a long, cold winter has mild average temperatures and moderate rain? Rain falling on a heavy snowpack increases the risk of ice jams.

Local Floods

Definition This type of flooding may or may not be associated with an extreme hydrologic event, but is caused by poor or blocked drainage. In many cases it is an annual event which occurs on agricultural land and has no major consequences, in other cases it can cause hardship58.

Discussion If either urban or rural areas are dependent upon pumps and pump stations to provide drainage assistance, when the water flow surpasses the inflow allowances, local flooding can occur. As well, storm drains, drainage ditches or natural drainage channels can become blocked by sediment, debris or ice; thus resulting in local flooding59.

It Happened Here… In late April 2008, the Albany River flooded, affecting the small, rural First Nations communities of Kashechewan and Fort Albany in Ontario. Kashechewan (population 1,200) was evacuated, for the fourth time in four years due to flooding. Flooding damaged homes, the airport and hospital60. From July 19-20, 1996, the Saguenay-Lac-Saint-Jean region of Quebec was affected by massive floods, due to both human and natural causes. The key human-related cause was poor maintenance of the region’s dikes and dams. Damages totaled $1.5M. There were 10 fatalities and more than 16,000 evacuated. The Aboriginal reserve of Mashteuiatsh (population 1,749) was among the many communities affected61.


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Local Floods 62,63,64 65 66 67-Human-caused


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FACTORS

Are there areas in your community that experience fast runoff due to road grids directing the water flow to a limited storm sewer capacity?

Are there areas in your community where streams or rivers have been diverted from their original direction?

Are there areas in your community near a dam where the infrastructure is aging and not kept repaired and/or where the intensity of water flow exceeds the capacity of the dam?

Are there areas in your community that are dependent upon pumps and pump stations to provide drainage assistance?

Are there areas in your community where storm drains, drainage ditches or natural drainage channels are next to or downhill from areas of soil and sediment that can wash over and block these drainage systems?

Are there areas in your community that experience freezing temperatures in winter and where storm drains, drainage ditches or natural drainage channels can become blocked by ice?

Scientists have observed that with climate change there are communities which are experiencing higher amounts of rainfall and thus increasing the likelihood of flooding. Is your community experiencing increased rainfall?

Rain Storm Floods

Definition The basic cause of most river floods is excessive rainfall which cause significant elevations in river levels68. The effect of elevated water levels is the flooding of low lying river floodplain areas.

Discussion Flood-producing rainfalls tend to cause quicker floods, either due to storms of intense rainfall or during rain-on-snow events where a warming trend and rainfall follows a shallow snowfall69. There have been several billion dollars of insured damages due to flood disasters in Canada—the most expensive of which was the 1950 Red River valley flood in southern Manitoba, costing $1,093million. The majority of flood disasters in Canada (65%) are caused by snowmelt, rainfall or a combination of the two. Damage caused by flooding is related to factors such as the depth of the water, the duration of elevated water levels, the velocity of flood waters over flooded land, rate of water rise, the frequency of floods and the timing of floods70.

It Happened Here… From July 21 to 22, 2008, a tropical rain storm drenched Nova Scotia, including the small town of Clark’s Harbour (population 860). The amount of rain received in the 24-hour period equaled approximately the amount usually received in an entire month71.


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On January 26, 2005 in the small community of Willow Creek, BC seven homes were damaged by flooding and 6 more were threatened along Arnett Road.72 In early June 2010 Maple Creek, in southwestern Saskatchewan, experienced very heavy rains which flooded basements and collapsed a portion of the Trans-Canada Highway.73

Rain Storm Floods,74 - Natural


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FACTORS

Are there areas in your community with frequent high winds?

**Are there areas in your community with frequent storms that have a wide geographical range (as opposed to localized storms)? These areas are at greater risk from rain storms because the water basin will fill faster.

Are there areas in your community when there is constant rainfall? Areas where the soil is already saturated before a storm comes are more at risk.

Are there areas in your community that historically receive annual, long-duration storms and have small watersheds in relation to the rainfall received?

Are there areas in your community on or near flood plains (low lying, flat ground) that have received long and intense periods of rainfall in the past?

Snow Melt Floods

Definition River floods can also be caused by snow melts (freshets) which cause significant elevations in river levels75. This has the same effect of causing flooding in low-lying areas.

Discussion The size of the river catchment, as well as the intensity of the meteorological event, is critical in determining the character of flooding. Flooding caused by snow melt events tend to occur in the late spring and the magnitude of such flooding is tied directly to the amount of winter snow pack. Floods occur throughout the year in Canada, but are concentrated (40%) in April and May, due to snowmelt76. Characteristics of snow melt floods are that the flood duration may last for days or weeks as compared to smaller drainages or coastal flooding from smaller river systems which may last only a few hours. Snow melt floods are generally easier to monitor and forecast77.

It Happened Here… In May 2008, New Brunswick experienced severe spring flooding along the Saint John River. Many communities were affected, including the small town of Prince William (population 879). Numerous factors caused the flood: record-setting snow pack, which remained into the spring; sudden warming and heavy rains. The flood was the most extensive in 35 years. It impacted 1,600 properties, causing over $50M in damages. No deaths or injuries were reported78.


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In April 1999, the town of Melita, Manitoba (population 1,051) experienced major flooding as a result of rapid snow melt. The flooding of the Souris River washed out roads and damaged bridges in rural areas, and made 800,000 hectares of farmland unseedable.79

Snow Melt Floods80,81 82- Natural and Human-caused


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FACTORS

**Are there areas in your community near rivers fed by vast quantities of snowmelt in the spring? Thicker and dense snowpack, combined with a fast melt rate, increase risk.

Are there areas in your community with a water basin prone to runoff (small capacity, narrow shape, steep slope, lack of vegetation on surrounding land, and surrounding surfaces do not absorb water)?

**Are there areas in your community with a large amount of rapid runoff as well as typically sunny weather in the spring?

Are there areas in your community in which the spring following a long, cold winter has mild average temperatures and moderate rain? Rain falling on a heavy snowpack increases the risk of ice jams.

Scientists have noted that with climate change there are changes in increased snowfalls and rainfalls during the winter over much of North America, which could result in increased runoff and river flows in winter and spring. Has your community experienced increased snow and rainfall amounts over the winter?

Glaciers

Definition A glacier is a permanent is a large body of ice, consisting largely of re-crystallized snow that shows evidence of downslope or outward movement due to the pull of gravity. There are several types of glaciers including:

• mountain glaciers which are relatively small glaciers located at high elevations in mountains;

• cirque glaciers which occupy depressions on the sides of mountains and which can grow and spread into valleys and flow down the valleys as valley glaciers.

• valley glaciers can extend down to sea level and may carve a narrow valley into the coastline, in which case they are called fjord glaciers - if a valley glacier extends down a valley and then covers a gentle slope beyond the mountain range, it is called a piedmont glacier; and

• ice sheets are the largest types of glaciers on Earth and cover large areas of the land surface, including mountain areas.83


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Discussion In Canada, an estimated area of 200 000 square kilometres, or about 2% of the country’s area is covered by glaciers and icefields. A huge quantity of freshwater is frozen in the polar ice caps and in high mountain glaciers. Glaciers and icefields are found in western Canada and the mountains in the eastern Arctic.84 Currently many Canadian glaciers are melting due to warming temperatures. Seasonal meltwater from glaciers is a resource of freshwater that is used in many different ways: hydroelectric power generation, the development of freshwater habitats, domestic water use, and irrigation. Glaciers act as water savings accounts, storing water during cool, wet climate and releasing it during warm, dry climate. Over the short term, increased melting causes increased water levels in streams and rivers but high levels of warming temperatures can result in lake outbursts and rapid ice advances on to land or out to sea that can be dangerous and destructive. Over the long-term, high rates of melting and prolonged “mass wastage” will eventually exhaust the glacier resource and result in far-reaching consequences for communities that rely upon glacier meltwater for freshwater in the summer months.85

It Happened Here… Clearcut logging and a receding glacier were pinpointed Tuesday as probable contributors to a devastating flood which swept through the remote British Columbia First Nations community of Kingcome Inlet in September 2010. Helicopters provided the only way out for about 120 residents when water quickly rose up to four metres in parts of the village.

Glaciers,86,87 88- Natural


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FACTORS

**Are there areas in your community on the coast or near sea level? Global climate change contributes to glaciers melting more than they are replenished each year, contributing to sea level rise.

**Are there areas in your community that depend on glacier melt for drinking water, irrigation and/or hydroelectric power? These areas are at risk of such water sources running out due to climate change. The consequence of rapid glacier melting rates is often that underground water levels increase in the short term and decrease in the long term.)

Are there areas in your community located in the valleys below glaciers? These areas are at risk of large amounts of sediment being deposited in the valleys as the glaciers melt.

Scientists have noted that in many parts of Canada annual maximum winter and summer temperatures have been rising and thus glacier melting has increased. Is your community close to a glacier and have temperatures been rising over the past several years?


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IceFlows, Icebergs, Ice Islands and Sea Ice

Definition When seawater freezes, it is only the water that forms into ice crystals. The salt becomes trapped between the crystals in a concentrated brine that eventually leaches out, leaving mostly pure ice floating on the surface, surrounded by sea water of increased salinity and density. Since the ice displaces its own weight in this denser water, it does not displace as much volume as it occupied before freezing. Because of this, freezing has an effect similar to that of evaporation - it lowers the water level and increases the surface salinity and density. Surface water must therefore flow toward a region of freezing, while the cold salty water that is formed must sink and flow away from the region89.

Discussion Ice shelves are sheets of ice floating on water and attached to land. They may extend hundreds of km. from land and reach thicknesses of 1000 m. Permanent and seasonal sea ice can be found near a significant portion of Canada’s coastlines—posing fishing, navigation and other marine hazards90.

It Happened Here… In July 1981, a 900-tonne Canadian survey ship called the Arctic Explorer struck an iceberg. The accident occurred just off the coast of Newfoundland, near the small town of St. Anthony (population 2,476). Thirteen crewmen died; 19 survived by life raft; the ship sank in 20 minutes91.

Icebergs, Ice Islands and Sea Ice92,93 94- Natural


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FACTORS

Are there areas in your community on the coast that experience long, cold, freezing winters and with frequent marine traffic? These areas are more at risk of marine accidents due to icebergs, ice islands or sea ice.

**Are there areas in your community that have experienced hazards due to icebergs, ice islands or sea ice in the past?

Is your community on the Atlantic coast of Canada? Rising global temperatures contribute to large icebergs to break off and float south (especially on the Atlantic).

**Is your community located on the Labrador Current along Newfoundland’s coast or near shipping passages in the Northern Canada? These areas are at greatest risk.


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Lake Outburst

Definition Rapid accumulation of water in glacial lakes can result in a sudden discharge of large volumes of water and debris and causing flooding in the downstream. Glacial lake outburst flood causes disasters to life and property along the downstream, results serious death tolls and destruction of valuable forests, farms and costly mountain infrastructure95. Glacier-dammed lakes are also called jökulhlaups.

Discussion Lake outburst floods can result due to the faster rate of ice and snow melting, possibly caused by the global warming, as well as landslides. As well, the lakes may drain through or underneath the ice, or over the ice. Glacier-dammed lakes may remain stable for some time and then release suddenly, or they may slowly fill and then release on a periodic basis.96 Once an outburst flood ceases, the lake can refill if the glacier dam reforms. A reformed glacial lake can drain again at some time in the future. Although most jökulhlaups in Canada occur in remote areas, they can pose a serious threat to infrastructure, forest lands and fish habitat far downstream from the glacier dam.97 Lake dams can form in basins vacated by retreating glaciers, typically in cirques and steeped-walled valleys. Some of these dams are vulnerable to rapid erosion by waters flowing from the lake, which may lead to a catastrophic outburst flood. Since 1925, there have been at least ten outburst floods from moraine-dammed lakes in the western part of Canada taking up most of British Columbia, the Yukon, and cutting into the Rocky Mountains. Like jökulhlaups, floods from moraine-dam failures occur in remote areas, but they pose a serious threat to infrastructure, forest lands and fish habitat far downstream from the lake basin.98

It Happened Here… In July 1994, an ice-dammed lake at Goddard Glacier in British Columbia suddenly drained and flooded the surrounding area. Near the community of Chilko Lake (population 62) the flood deposited sediment, destroyed large areas of forest and changed the Farrow Creek channel. Causes include rainfall levels greater than average and snowmelt99. In 1978, debris flows in Kicking Horse Pass were triggered by a lake outburst from Cathedral Glacier which destroyed three levels of Canadian Pacific railway track, derailing a freight train. Sections of the Trans-Canada Highway were also buried.100


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Lake Outburst101 - Natural


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FACTORS

Are there areas in your community in high mountain valleys, just downhill or downstream from glacier-dammed lakes? These areas are at greater risk of an outburst flood from a glacier dam failure.

Is there a failure to implement regular aerial checks on glaciers to ensure that that there is no build up of a glacial lake behind potentially unstable soil?

Are there regular checks to ensure that beavers have not created potential lake outbursts by creating a network of dams in mountainous glacial terrain?

Glacial lakes can drain and then reform. Have there been previous glacial dams in or near your community?

Risk Assessment Resources

Related Resources Accident Resource

Avalanches

Natural Resources Canada’s “The Atlas of Canada” provides a lot of information about major avalanches in Canada. http://atlas.nrcan.gc.ca/site/english/maps/environment/naturalhazards/naturalhazards1999/majoravalanches The Canadian Avalanche Centre provides timely information and warnings regarding avalanches and also includes an Avalanche Danger Scale. http://www.avalanche.ca/cac/bulletins/regions

Drought

This website provides all kinds of information regarding drought management in Canada. http://www4.agr.gc.ca/AAFCAAC/displayafficher.do?id=1256665877504&lang=eng

Floods

Public Safety Canada provides useful information regarding floods in Canada. http://www.publicsafety.gc.ca/res/em/nh/fl/index-eng.aspx


HYDROLOGICAL 17

Environment Canada also provides useful information regarding floods in Canada. http://www.ec.gc.ca/eauwater/default.asp?lang=En&n=65EAA3F5 Natural Resources Canada’s “The Atlas of Canada” provides a lot of information about floods, including major floods from 1902 to 2005. http://atlas.nrcan.gc.ca/site/english/maps/environment/naturalhazards/floods/majorfloods The Institute for Catastrophic Loss Reduction (ICLR) has a lot of information about a number of natural hazards including Floods. http://www.iclr.org


18 HYDROLOGICAL

References 1 CBC News. Retrieved March 13 2011 from http://archives.cbc.ca/environment/natural_disasters/topics/1483-9938/ and

http://www.thecanadianencyclopedia.com/index.cfm?PgNm=TCE&Params=M1ARTM0011879 2 The Vancouver Sun, January 3 1997. 3 Campbell, C. (2007). Current and future snow avalanche threats and mitigation measures in Canada. Canadian

Avalanche Association. 4 Foley, Michael E. and Loiselle, Marc C., (2004) Paper No. 35-5 Landslide Susceptibility Mapping in Maine. Maine

Geological Survey, 22 State House Station, Augusta Maine. 5 Mclung, David and Schaerer, Peter (2006). The Avalanche Handbook. Mountaineers Press, Seattle. 6 Campbell, C. (2007). Current and future snow avalanche threats and mitigation measures in Canada. Canadian

Avalanche Association. 7 Foley, Michael E. and Loiselle, Marc C., (2004) Paper No. 35-5 Landslide Susceptibility Mapping in Maine. Maine

Geological Survey, 22 State House Station, Augusta Maine. 8 Mclung, David and Schaerer, Peter (2006). The Avalanche Handbook. Mountaineers Press, Seattle. 9 Fuchs, S., Thoeni, M., McAlpin, M. C., Gruber, U., & Bruendl, M. (2007). Avalanche hazard mitigation strategies

assessed by cost effectiveness analyses and cost benefit analyses - evidence from davos, switzerland. Natural Hazards, 41(1), 113-129

10 Parry, L., O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson. (eds.). (2007). “Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.” Cambridge University Press, Cambridge, UK.

11 United Nations Disaster Relief Co-ordinator. 1991. Mitigating Natural Disasters: Phenomena, Effects and Options: A Manual for Policy Makers and Planners. New York United Nations 1991

12Schuster, R.L. and D.R. Crandell. 1984. “Catastrophic Debris Avalanches from Volcanoes” in Proceedings, IV International Symposium on Landslides, V.1, 567-772 Downsview, Ont.: Canadian Geotechnical Society

13Eisbacher, C.H. and Clague J. 1981. “Urban Landslides in the Vicinity fo Vancouver, British Columbia, with Special Reference to the December 1979 Rainstorm”. Canadian Geotechnical Journal18: 205-16

14 O'Loughlin, C.L. 1972. “A Prelimary Study of Landslides in the Coast Mountains of Southwestern British Columbia” in H.O. Slaymaker and H.J. McPherson (eds.), Mountain Geomorphology, 101-112. B.C. Geographic Series No. 14, Vancouver: Tantalus Research Ltd.

15 Environment Canada. Retrieved April 17 2011 from http://www.ec.gc.ca/eau-water/default.asp?lang=En&n=B7B62836-1

16 The Canada Country Study. Climate Impacts and Adaptation. Retrieved February 25 2011 from http://dsp-psd.pwgsc.gc.ca/Collection/En56-119-7-1998E.pdf

17 Pearce, Laurie. 1997. British Columbia: Hazard, Risk and Vulnerability Analysis. Vancouver, BC: Disaster Preparedness Resources Centre, UBC.

18 Natural Resources Canada. Landslides. Retrieved March 20 2005 from http://landslides.nrcan.gc.ca/db_templates/photo_library_one_e. aspx?id=30

19 Foley, Michael E. and Loiselle, Marc C., (2004) Paper No. 35-5 Landslide Susceptibility Mapping in Maine. Maine Geological Survey, 22 State House Station, Augusta Maine.

20 Ministry of Energy, Mines, and Petroleum Resources. “Landslides in BC.” 2007 http://www.em.gov.bc.ca/Mining/Geolsurv/Surficial/landslid/

21 United States Geological Survey (2010).“Landslide Hazards Program.” Retrieved Jan 12 2011 from www.landslides.usgs.gov

22 van Westen, C. J., van Asch, T. W. J., & Soeters, R. (2006). Landslide hazard and risk zonation - why is it still so difficult? Bulletin of Engineering Geology and the Environment, 65(2), 167-184.

23 King, Hobart, Cole, Bradley, King, Angela,Ball, Jessica, Rittenhouse, Laura. (2011). “Geology.com.” Retrieved March 11 2011 from http://geology.com/articles/debris-flow/

24 Foley, Michael E. and Loiselle, Marc C., (2004) Paper No. 35-5 Landslide Susceptibility Mapping in Maine. Maine Geological Survey, 22 State House Station, Augusta Maine.

25 Ministry of Energy, Mines, and Petroleum Resources. “Landslides in BC.” 2007 http://www.em.gov.bc.ca/Mining/Geolsurv/Surficial/landslid/

26 United States Geological Survey (2010).“Landslide Hazards Program.” Retrieved Jan 12 2011 from www.landslides.usgs.gov

27 van Westen, C. J., van Asch, T. W. J., & Soeters, R. (2006). Landslide hazard and risk zonation - why is it still so difficult? Bulletin of Engineering Geology and the Environment, 65(2), 167-184.

28 King, Hobart, Cole, Bradley, King, Angela,Ball, Jessica, Rittenhouse, Laura. (2011). “Geology.com.” Retrieved March 11 2011 from http://geology.com/articles/debris-flow/

29 Sassa, K., Canuti, P. (2009). Landslides: Disaster Risk Reduction. Berlin: Springer. 30 Watson, R.T., M. C. Zinyowera, R.H. Moss. (eds.). (1997). The Regional Impacts of Climate Change: An Assessment of

Vulnerability. IPCC. Cambridge University Press, UK. 31 Parry, L., O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson. (eds.). (2007). “Contribution of Working

Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.” Cambridge University Press, Cambridge, UK.


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32 Parry, L., O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson. (eds.). (2007). “Contribution of Working


33 McKay, G.A. 1988. “Drought: A Global Perspective” in M.I. El-Sabh and T.S. Murty (eds.), Natural and Man-Made Hazards. Dordrecht, Holland: D. Reidel Publishing Company

34 McKay, G.A. 1988. “Drought: A Global Perspective” in M.I. El-Sabh and T.S. Murty (eds.), Natural and Man-Made Hazards. Dordrecht, Holland: D. Reidel Publishing Company

35 Environment Canada. Retrieved February 14 2011 from http://www.ec.gc.ca/meteo-weather/default.asp?lang=En&n=F2AE9E49-1 and http://en.wikipedia.org/wiki/Balgonie,_Saskatchewan

36 McGinn, Sean. Weather and Climate Patterns in Canada’s Prairie Grasslands. Retrieved March 12 2011 from www.biology.ualberta.ca/bsc/english/grasslandsbook/Chapter5_ACG.pdf and http://www.discoverthepeacecountry.com/htmlpages/eaglesham.html

37 Jülich, Sebastian. (2006). “Drought Risk Indicators.” Doctoral Research, Department of Geography, University of Bonn, Germany. Retrieved January 2, 2011 from www.ehs.unu.edu/file/get/4197

38 Australian Water Resources (2005). “Water Availability.” Retrieved January 3, 2011 from http://www.water.gov.au/Default.aspx

39 Jülich, Sebastian. (2006). “Drought Risk Indicators.” Doctoral Research, Department of Geography, University of Bonn, Germany. Retrieved January 2, 2011 from www.ehs.unu.edu/file/get/4197

40 Australian Water Resources (2005). “Water Availability.” Retrieved January 3, 2011 from http://www.water.gov.au/Default.aspx

41 Cooka, Benjamin I., Ron L. Millerb, and Richard Seagera. (2009). “Amplification of the North American ‘Dust Bowl’ drought through human-caused land degradation.” Goddard Institute for Space Studies. Retrieved February 7, 2011 from http://www.pnas.org/content/106/13/4997.full

42 Gan, Thian Yew. (2000). “Reducing Vulnerability of Water Resources of Canadian Prairies to Potential Droughts and Possible Climatic Warming.” Water Resources Management, 14(2), 111-135.

43 Watson, R.T., M. C. Zinyowera, R.H. Moss. (eds.). (1997). The Regional Impacts of Climate Change: An Assessment of Vulnerability. IPCC. Cambridge University Press, UK.

44 Parry, L., O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson. (eds.). (2007). “Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.” Cambridge University Press, Cambridge, UK.

45 Weather Eye. Retrieved March 12 2005 from http://weathereye.kgan.com/cadet/flood/about.html 46 CBC News Retrieved February 14 2011 from http://www.cbc.ca/news/canada/manitoba/story/2009/04/20/mb-flood-

expanse.html and http://en.wikipedia.org/wiki/2009_Red_River_flood#Flooding_and_ice_jam_mitigation_considerations and http://www.ec.gc.ca/meteo-weather/default.asp?lang=En&n=55615A16-1

47 Natural Resources Canada. Retrieved April 17 2011 from http://gsc.nrcan.gc.ca/floods/boisfrancs/index_e.php 48 Associated Programme on Flood Management. (2007). “Guidance on Flash Flood Management.” Retrieved January 3,

2011 from www.gwpceeforum.org/File/regional_publications/apsm_web.pdf 49 MetEd. (2006). “Flash Flood Early Warning System Reference Guide.” Retrieved January 3, 2011 from

www.meted.ucar.edu/hazwarnsys/ffewsrg/FF_EWS.Chap.2.pdf 50 Natural Resources Canada (2009). “The Atlas of Canada.” Retrieved January 8, 2011 from

http://atlas.nrcan.gc.ca/site/english/maps/environment/naturalhazards/floods/1 51 PBS. (2010). “The Hows and Whys of floods.” Retrieved January 15, 2011 from

http://www.pbs.org/newshour/infocus/floods/science.html 52 Environment Centre of University of Toronto. Retrieved March 20 2005 from http://www.utoronto.ca/env/nh/pt2ch2-3-

2.htm 53 Institute of Catastrophic Loss Reduction. Retrieved February 12 2011 from

http://www.iclr.org/pdf/ICLR_%20Flood%20Report.pdf 54Atlantic Canada History. Retrieved February 12 2011 from http://atlanticcanadahistory.com/gpage27.html and

http://www.city-data.com/canada/Hartland-Town.html 55 Department of Natural Resources, Newfoundland. Floods. Retrieved April 17 2011 from

http://www.nr.gov.nl.ca/nr/mines/outreach/disasters/flooding/badger.html 56 Beltaos, Spyros and Brian C. Burrell. (2000). “Extreme ice jam floods along the Saint John River New Brunswick,

Canada.” The Extremes of the Extremes: Extraordinary Floods, 271: 9-14. 57 The Canadian Encyclopedia. (2011). “Floods and Flood Control.” Retrieved January 15, 2011 from

http://www.thecanadianencyclopedia.com/index.cfm?PgNm=TCE&Params=A1ARTA0002863 58 Hay, D. 1992. “The Flood Hazard” in Peter Borowsky (ed.), Geologic Hazards in British Columbia: Proceedings of the

Geologic Hazards ’91 Workshop: February 20-21, 1991, Victoria, B.C. Victoria: University of Victoria. 59 Hay, D. 1992. “The Flood Hazard” in Peter Borowsky (ed.), Geologic Hazards in British Columbia: Proceedings of the

Geologic Hazards ’91 Workshop: February 20-21, 1991, Victoria, B.C. Victoria: University of Victoria. 60Ontario Hazards. Retrieved March 10 2011 from http://ontario.hazards.ca/historical/Flood_Ontario-e.html and

www.cbern.ca/research/projects/workspaces/cura.../fort_albany/ 61Natural Resources Canada. Retrieved February 23 2011 from

http://ess.nrcan.gc.ca/2002_2006/nher/k02_supplement_e.php and http://archives.cbc.ca/for_teachers/137/ and http://en.wikipedia.org/wiki/Saguenay-Lac-Saint-Jean


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62 Associated Programme on Flood Management. (2007). “Guidance on Flash Flood Management.” Retrieved January 3,

2011 from www.gwpceeforum.org/File/regional_publications/apsm_web.pdf 63 MetEd. (2006). “Flash Flood Early Warning System Reference Guide.” Retrieved January 3, 2011 from

www.meted.ucar.edu/hazwarnsys/ffewsrg/FF_EWS.Chap.2.pdf 64 Natural Resources Canada (2009). “The Atlas of Canada.” Retrieved January 8, 2011 from

http://atlas.nrcan.gc.ca/site/english/maps/environment/naturalhazards/floods/1 65 PBS. (2010). “The Hows and whys of floods.” Retrieved January 15, 2011 from

http://www.pbs.org/newshour/infocus/floods/science.html 66 Watson, R.T., M. C. Zinyowera, R.H. Moss. (eds.). (1997). The Regional Impacts of Climate Change: An Assessment of

Vulnerability. IPCC. Cambridge University Press, UK. 67 Parry, L., O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson. (eds.). (2007). “Contribution of Working

Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.” Cambridge University Press, Cambridge, UK


69 Hay, D. 1992. “The Flood Hazard” in Peter Borowsky (ed.), Geologic Hazards in British Columbia: Proceedings of the Geologic Hazards ’91 Workshop: February 20-21, 1991, Victoria, B.C. Victoria: University of Victoria.


71 Atlantic Canada History. Retrieved February 12 2011 from http://atlanticcanadahistory.com/gpage27.html and http://www.roadsidethoughts.com/ns/baccaro-profile.htm

72 PECC Sit Report - January 26, 2005. 73 CTV News. Retrieved March 25 2011 from http://ottawa.ctv.ca/servlet/an/local/CTVNews/20100708/harper-flood-tour-

saskatchewan-100708/20100708/?hub=OttawaHome 74 United States Geological Survey (2010). “Water science for schools.” Retrieved January 8, 2011 from

http://ga.water.usgs.gov/edu/100yearflood.html 75 Hay, D. 1992. “The Flood Hazard” in Peter Borowsky (ed.), Geologic Hazards in British Columbia: Proceedings of the

Geologic Hazards ’91 Workshop: February 20-21, 1991, Victoria, B.C. Victoria: University of Victoria. 76 Natural Resources Canada. Floods. Retrieved February 12 2011 from http://gsc.nrcan.gc.ca/floods/database_e.php 77 Hay, D. 1992. “The Flood Hazard” in Peter Borowsky (ed.), Geologic Hazards in British Columbia: Proceedings of the

Geologic Hazards ’91 Workshop: February 20-21, 1991, Victoria, B.C. Victoria: University of Victoria. 78 Environment Canada. Retrieved February 12 2011 from http://www.ec.gc.ca/meteo-

weather/default.asp?lang=En&n=7D6FDB7C-1 and http://www.city-data.com/canada/Prince-William-Parish.html 79 Public Safety Canada. Flooding. Retrieved April 17 2011 from http://www.publicsafety.gc.ca/res/em/nh/fl/fl-sig-eng.aspx 80 Natural Resources Canada (2007). “Flood Disasters in Canada.” Retrieved January 8, 2011 from

http://gsc.nrcan.gc.ca/floods/database_e.php 81 NOAA Brochure. (2002). “Floods and Flash Floods The Awesome Power” Retrieved January 15, 2011 from

http://www.env.gov.bc.ca/wsd/public_safety/flood/flood_hazards.html 82 Watson, R.T., M. C. Zinyowera, R.H. Moss. (eds.). (1997). The Regional Impacts of Climate Change: An Assessment of

Vulnerability. IPCC. Cambridge University Press, UK. 83 Earth Science Australia. Glaciers. Retrieved April 17 2011 from http://earthsci.org/index.html 84 Natural Resources Canada. Glaciers. Retrieved April 17 2011 from

http://atlas.nrcan.gc.ca/site/english/maps/freshwater/distribution/glaciers/1/ 85 Natural Resources Canada. Glaciers. Retrieved April 17 2011 from

http://atlas.nrcan.gc.ca/site/english/maps/freshwater/distribution/glaciers/1/ 86 Barnett, T. P., J. C. Adam & D. P. Lettenmaier. (2005). Potential impacts of a warming climate on water availability in

snow-dominated regions. Nature 438: 303-309. 87 Schiefer, E., B. Menounos, & R. Wheate. (2007). “Recent volume loss of British Columbian glaciers, Canada.”

Geophysical Research Letters, 34:1-6. 88 Parry, L., O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson. (eds.). (2007). “Contribution of Working


89 Government of Canada. Retrieved March 20 2005 from http://www.lau.chs-shc.dfo-mpo.gc.ca/english/Phenomena3.shtml

90 Public Safety Canada. Icebergs, sea ice and fog. Retreived February 12 2011 from http://www.publicsafety.gc.ca/res/em/nh/isif/index-eng.aspx

91 Public Safety Canada. Icebergs, sea ice and fog. Retreived February 12 2011 from http://www.publicsafety.gc.ca/res/em/nh/isif/index-eng.aspx and http://www.city-data.com/canada/St--Anthony-Town.html

92 Public Safety Canada. (2007). “Icebergs, Sea Ice and Fog.” Retrieved January 15, 2011 from http://www.publicsafety.gc.ca/res/em/nh/isif/index-eng.aspx

93 Solcomhouse. (2007). “Icebergs.” Retrieved January 15, 2011 from http://www.solcomhouse.com/iceberg.htm 94 Parry, L., O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson. (eds.). (2007). “Contribution of Working



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95 AIT-UNEP Regional Resource Centre for Asia and the Pacific (RRC.AP) Retrieved February 12 2011 from

http://www.rrcap.unep.org/issues/glof/ 96 Environment Canada. Retrieved April 17 2011 from http://www.ec.gc.ca/eau-water/default.asp?lang=En&n=B7B62836-

1 97 Natural Resources Canada (2009). “The Atlas of Canada.” Retrieved January 8, 2011 from

http://atlas.nrcan.gc.ca/site/english/maps/environment/naturalhazards/floods/1 98 Natural Resources Canada (2009). “The Atlas of Canada.” Retrieved January 8, 2011 from

http://atlas.nrcan.gc.ca/site/english/maps/environment/naturalhazards/floods/1 99 Clague, J.J., Evans, S.G. (1997). "The 1994 jökulhlaup at Farrow Creek, British Columbia, Canada". Geomorphology 19

(1): 77–87 and http://www.vancouverisland.com/regions/towns/?townID=4010 100 Environment Canada. Water. Retrieved April 17 2011 from http://www.ec.gc.ca/eau-

water/default.asp?lang=En&n=B7B62836-1 101 Natural Resources Canada. The Atlas of Canada. Floods. Retrieved April 3 2011 from

http://atlas.nrcan.gc.ca/site/english/maps/environment/naturalhazards/floods/1/

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