D. Structures and Mechanisms · Forces Acting on Structures

Protecting Communities: Urban, Rural and Remote

D1.2 A1.5 A3.1 A3.3About 45 minutes

Learning goals

I can describe ways people mitigate (reduce) the impacts of forces from natural phenomena on structures.
I can compare how urban, rural and remote communities protect their structures.
I can assess a way of mitigating impacts using criteria like how well it works, cost, the environment and fairness.
I can describe contributions of Inuit knowledge to building in the North.

Words to know

mitigate
To make something less severe or less harmful.

urban
In a city or large town, with many people and buildings close together.

rural
In the countryside, with farms, small towns and lots of open land.

remote
Far from cities and main roads, often reached only by plane, boat or winter road.

floodplain
Low, flat land beside a river that floods when the river overflows.

windbreak
A row of trees or a fence that slows the wind (on farms, also called a shelterbelt).

criteria
The things you check to judge how good something is. (One is a criterion.)

Don't just rebuild, plan ahead

We can't stop an ice storm or a flood. But people can mitigate (reduce) the harm they do. Different communities do this in different ways, because a big city, a farming area and a far-north community face different forces and have different resources.

Today you will compare urban, rural and remote communities and assess (judge) how well their solutions work.

Five big ways to mitigate

Build stronger: follow building codes, add bracing, strong connections and stronger roofs (Lesson 4).
Build in safer places: don't build on floodplains or unstable slopes.
Use nature: wetlands soak up floodwater like a sponge; rows of trees slow the wind.
Warn people early: weather forecasters issue warnings so people can prepare, and towns can close roads before a flood.
Take care of structures: trim trees near power lines, clear deep snow off flat roofs, clean drains and culverts, and inspect bridges.

A cattail marsh full of water beside a farm field, with a row of tall trees and a farmhouse in the distance. — Wetlands like this marsh soak up floodwater like a sponge, and the row of trees slows the wind: two ways rural communities use nature to reduce harm. AI-generated image

Urban communities (cities)

Toronto: in October 1954, Hurricane Hazel brought huge amounts of rain. Rivers flooded, and many homes built on low land beside the rivers were washed away. Many people died. Afterward, the Toronto area made rules against building homes on the floodplains, and much of that land became parks and trails. Today a flood there damages park land instead of homes.
Winnipeg: the Red River Floodway is a huge channel dug around the city. When the Red River floods, extra water is sent through the floodway, around the city instead of through it. It was first built in the 1960s.
Cities also use storm sewers, green roofs (roofs covered in plants that soak up rain) and ponds that hold stormwater.

Rural communities (the countryside)

Windbreaks: farmers plant rows of trees, called shelterbelts, around farmyards and fields. They slow the wind, which protects buildings and keeps soil from blowing away.
Snow fences: fences set up beside highways catch drifting snow before it piles up on the road.
Drainage: ditches and culverts carry water away from roads and fields. They must be kept clear.
Farmers clear heavy snow from barn roofs and fasten down equipment and buildings before storms.

The fence slows the wind, so the blowing snow drops into a drift before it reaches the road. Plows are still needed for snow that falls right on the highway.

Remote communities (far North and fly-in communities)

Permafrost: in the far North, the ground stays frozen all year. If a building's heat thaws the ground under it, the ground gets soft and the building can tilt and crack. So many buildings in places like Nunavut are raised on steel piles with an air gap underneath. Cold air flows under the building and keeps the ground frozen.
Hard to repair: many remote communities have no road to the south. Supplies arrive by plane, by ship in summer, or over winter roads built on frozen ground and lakes. Many First Nations communities in northern Ontario depend on winter roads. Because repairs are slow and costly, structures must be built to last, and communities keep extra supplies. Warmer winters can make the winter road season shorter.
Inuit knowledge: Inuit have lived in the Arctic and built with snow for a very long time. An iglu (snow house) has a dome shape that stands up to strong winds and the weight of snow, and the snow blocks keep the cold out. Many Inuit still know how to build an iglu as a shelter when travelling on the land. Inuit knowledge of snow, ice and weather also helps people travel and build safely in the North.

A house in the far North raised on steel piles. The air gap lets cold air flow underneath, so the building's heat doesn't thaw the frozen ground (not to scale).

Criterion	Question to ask
How well does it work?	Does it really reduce the damage?
Cost	How much does it cost to build and to keep up?
Environment	Does it help or harm nature?
Fairness	Who is protected? Is anyone left out or put at more risk?
How long it lasts	Will it still work in 10 or 50 years, even with a changing climate?

Criteria for assessing a way to mitigate impacts

Worked example

Let's assess snow fences

A rural highway is often blocked by drifting snow. Assess snow fences as a solution, compared with plowing more often.

How well it works: snow fences catch blowing snow before it reaches the road, so fewer drifts form. Plows clear snow only after it builds up.
Cost: fences cost money to put up, but then cost little; plowing more often needs more fuel and drivers every storm.
Environment: fences use little energy; more plowing uses more fuel and more road salt may be spread.
Fairness: both help everyone who drives the road.
Conclusion: snow fences are a good choice where wind blows snow across a road, and plows are still needed for snow that falls directly on it.

Snow fences work well, cost less over time and are better for the environment, but they work with plowing, not instead of it.

Worked example

Let's assess building on piles in the North

Assess raising buildings on steel piles over permafrost.

How well it works: the air gap keeps the ground frozen and firm, so buildings don't tilt or crack.
Cost: piles cost more to install, and materials must be flown or shipped in. But fixing a cracked, tilting building would cost even more.
Environment: it protects the permafrost under the building.
How long it lasts: if the climate warms and the permafrost thaws deeper, piles may need to go deeper, or be adjustable.

Piles work well and save money over time, but they cost more at first, and builders must plan for a warming climate.

Just for fun

Riddle: What did the snow fence say to the blowing snow?

"Stop right there! This highway is closed to drifters."

Hands-on activity

Make a community protection plan

You need: paper, pencil, and a grown-up to help you research.

Decide: is your community urban, rural or remote?
With your grown-up, find out which natural phenomenon is the biggest risk where you live (for example: ice storms, floods, windstorms, heavy snow). Your town or city website or a library is a good place to look.
List three ways your community mitigates that risk (for example: snow plows, tree trimming, storm sewers, warnings, flood rules). Look for them on a walk!
Assess one of them with the criteria chart: how well it works, cost, environment, fairness, how long it lasts.
At home: make a list for a family emergency kit. The Government of Canada suggests being ready to take care of yourselves for at least 72 hours (3 days). Ideas: water, food that doesn't need cooking, a flashlight, batteries, a first aid kit, warm clothes, medicines.
Present your plan to your family like an expert: use the words mitigate, force and structure.

What to look for: the plan names a real risk, three real ways to mitigate it, an assessment with reasons, and a sensible emergency kit list.

Your turn

What does mitigate mean?

Name the five big ways to mitigate impacts of natural forces.

How does the Red River Floodway protect Winnipeg?

Why are many buildings in the far North raised on piles?

What is a windbreak, and how does it help a farm?

Why does an iglu's dome shape stand up well to Arctic weather?

More practice: warm-up

Is Toronto urban, rural or remote?

What is a floodplain?

What does a snow fence do?

How can wetlands help in a flood?

How long does the Government of Canada suggest families be ready to take care of themselves in an emergency?

More practice: on your own

After Hurricane Hazel, much floodplain land in the Toronto area became parks. Why is this a good use of that land?

Why must structures in remote communities be built to last?

How might warmer winters cause problems for some remote communities?

Name one way urban communities deal with heavy rain.

Give one reason why a solution that works in a city might not work in a remote community.

Challenge

A town wants to stop flooding on one street by building a wall along the river there. A scientist warns this could push more water toward a neighbouring farm. Assess the wall using the fairness criterion.

Inuit have built iglus for a very long time, and engineers today also use domes. What does this tell us about where good science and technology ideas come from?

Compare how an urban, a rural and a remote community might each prepare for an ice storm.

Check your understanding

Quiz

What does mitigate mean?

Which is a way rural communities slow the wind?

Why are many buildings on permafrost raised on piles?

After Hurricane Hazel, what happened to much floodplain land in the Toronto area?

Which criterion asks "Who is protected, and is anyone left out?"

Why must remote communities keep extra supplies for emergencies?

What shape gives an iglu its strength against wind and snow?

For parents and teachers

Big idea (D1.2): People mitigate the impacts of forces from natural phenomena by building stronger, building in safer places, using nature (wetlands, windbreaks), early warnings and maintenance. Solutions differ in urban (Toronto floodplain parks after Hurricane Hazel, Winnipeg's Red River Floodway, storm sewers), rural (shelterbelts, snow fences, drainage) and remote communities (buildings on piles over permafrost, winter roads, extra supplies). Students assess solutions with criteria. Inuit knowledge of snow and building (A3.3), community connections (A3.1) and presenting the plan (A1.5) are woven in.

How to help: Make the emergency kit list real: check what your family already has. Look up your municipality's emergency preparedness page together.

Common difficulties:

Judging a solution only by whether it works. Encourage your child to also think about cost, the environment and fairness.
Describing First Nations, Métis and Inuit peoples only in the past. Inuit and First Nations communities are living, modern communities; traditional knowledge continues alongside modern building.
Worry: an emergency kit is a calm, empowering way to talk about storms.