Water for Work

Educator's Notes

Water is a basic necessity of life. Water contributes not only to our survival, but also to the quality of our lives.

Human beings have harnessed water to improve their lives since the dawn of time. In some ways, the history of civilization is the story of how we have made water work for us in increasingly ingenious ways. As early as 5000 BC, our predecessors used irrigation to increase crop production. Archaeologists have found masonry sewers dating back to 2750 BC – and amazingly, water-flushed toilets have been found, dating back almost as far!

Water played – and continues to play – a special role in the growth of our nation. The first residents of the Atlantic Coast – the Mi'kmaq, Maliseet and Beothuk people – relied heavily on inland waterways to travel through the dense forests of what are now the Atlantic Provinces. The fur trade, which stimulated the exploration of Canada's vast interior, was totally dependent on water for transportation. Water powered the many mills that dotted the waterways of the Maritimes and Upper Canada, enabling the production and export of grain and lumber (among other products), two early economic staples. As Canadian industry diversified, water was put to new uses: as a coolant, a solvent, a dispersant, and as a source of hydroelectric energy.

Transportation of goods by water is still an efficient way to move bulk goods. Water is also the basis of cheap energy. Water is a raw material in the manufacture of chemicals, drugs, beverages, and hundreds of other products. It is an essential part of manufacturing processes that end in every kind of good: from airplanes to zippers. In other words, we depend on water for most of our technology, comforts and conveniences, and, or course, for personal hygiene and to flush away our waste.

Many people think that it really makes no difference how much water we use, or what we use it for. Actually, the way we use water is very important. Some uses, for example, are incompatible with others. Some uses remove water from the natural cycle for longer periods than do others. Worst of all, most industrial water uses may actually lower the quality of the water.

Much of the water in North America has been developed. In less than 100 years, we have developed thousands of huge lakes; some more than a hundred miles long; and have created more than 500 000 smaller lakes and ponds. We turn rivers into staircases for ships and we live in what some ecological writers call the "Age of Dams"¹.

Hydro-Québec's La Grande River power plant, completed in 1982, is the world's largest underground generating station. Three great rivers; the Eastmain, Opinaca, and the Caniapiscau; were diverted to feed the 500-mile-long La Grande project, doubling the mean annual flow of the La Grande River and increasing its winter flow by a factor of eight. In the resulting trade-off the Eastmain was reduced to little more than a stream, and over 6 000 square miles were flooded. Political leaders see such hydro-power projects as economic miracles, creating jobs, power-for-sale and a vast network of economic spin-offs. Environmentalists argue that such projects are ecologically devastating, and, in 1992, equated the damage to be caused by the proposed James Bay Hydroelectric Project to be on par with the destruction of the Amazon rain forest.

Quebec is not the only Canadian province seeking to develop its water resources. Manitoba has dams, diversions and altered flows on the Churchill and Nelson Rivers; Ontario has considered the re-development of Hudson Bay-bound rivers. Consider the impact of such development on the Hudson Bay region. How will it affect the ecological flux of the bays, the arctic char, the beluga whale, the bearded seal, the Canada goose, the Cree, the Inuit, even the fishermen of Newfoundland? What we do affects our neighbours – locally and globally.

Water quality should be of great concern to all water users – that is, to everyone in the world. Ultimately, we all draw from the same supply of water. Most Canadians live downstream from somebody else. Even if they don't, everyone in the world and everyone through the ages has drawn from the same basic supply of water. This basic supply has been used billions of times and is replenished continually through the hydrologic cycle. People are only now becoming aware of the real limits to the use of water, and are more conscious of when and where it is returned to nature, particularly if it is returned diminished in quality and/or quantity. We must learn to understand water use – where we use water, what to measure, what the main uses of water how, how our main uses compete and interfere with each other, and how to manage the growing competition for water resources.

Where We Use Water

The most obvious and immediate uses of water occur in its natural setting. These are referred to as instream uses. Fish live in water, and some birds and animals require aquatic habitat to survive. These are examples of non-human instream uses. Hydroelectric power generation, shipping and water-based recreation are examples of human instream uses.

Instream uses are not always harmless. For example, oil leaking from boat motors and freighters causes pollution. The large reservoirs required by hydroelectric power generating stations remove water by evaporation and completely change the river regime for downstream users.

The greatest number and variety of water uses occur on the land. These are called withdrawal uses. This terms is appropriate because the water is withdrawn from its source (a river, lake or groundwater supply), and is piped or channelled to different locations and users before it is collected again and returned to water source. Household and industrial uses, thermal and nuclear power generation, irrigation and livestock watering all fall into this category.

Most withdrawal uses "consume" some of the water, meaning less is returned to the source than was taken out. Furthermore, the water which is put back into its natural setting is often degraded. For example: water leaving our houses contains human and household wastes. The same is true of water used in many industrial processes. Often this liquid waste is only partially treated, if at all, before it is returned to nature.

A Brief Examination of Five Occurrences of Withdrawal Use

Thermal Power Generation
The production of one kilowatt-hour of electricity requires 140 litres of water for fossil fuel plants and 205 litres of water for nuclear power plants. Some of this water is converted to steam, which drives the generator producing the electricity. Most of the water used in thermal power generation, however, is used for condenser cooling.

Why is so much cooling water necessary? Because today's thermal energy production processes can only convert about 40% of the fuel's energy into useable electricity. The rest of the fuel's energy is wasted. This is a doubly inefficient process, in that firstly, about 60% of the energy from the fuel is wasted and secondly, the water required to cool the heat (to a temperature where it can be safely released into the environment) is itself wasted. This cooling requires a continuous flow of water to circulate through the condenser. All the cooling water is returned to the environment much warmer that its original temperature. Evidence of this warmed water can be found in the cooling ponds located on the grounds of most thermal powered generating stations (there's one located in Trenton, Pictou County).

Manufacturing
Water is the lifeblood of industry. It is used as a coolant, a solvent, a transport agent, and as a source of energy. An automobile coming off the assembly line, for example, will have used at least 120 000 litres of water – 80 000 litres to produce the tonne of steel from which the car is fabricated and 40 000 more for the actual fabrication process. Many thousands more litres of water are involved in the manufacture of the auto's glass, plastic and fabric components. Manufacturing accounted for 14% of water withdrawals in Canada in 1996². Paper and allied products, primary metals, and chemicals were the three main industrial users of water that same year.

Municipal Use
Can you imagine a city without water? People use water for drinking, cooking and for other household requirements. Water is also needed to clean our streets, fight fires, fill swimming pools, and water lawns and gardens. Where would this used water go without a sewerage system? Residential, commercial and public uses, along with the water lost from reservoirs and pipes, amounted to about 10% of all withdrawals in Canada in 1996. This figure does not include rural area usage, where water use is not measured. If rural domestic uses were included in the total domestic withdrawal statistic, it is expected that the total domestic withdrawal in Canada would rise to about 12%.

Agriculture
Farmers depend on water for livestock and crop production. Agriculture was the fourth largest use of water in Canada in 1996, accounting for 9% of total withdrawals. Water is withdrawn mainly for irrigation and livestock watering. Irrigation is necessary primarily in the drier parts of Canada, such as the southern regions of Alberta, British Columbia, Saskatchewan, and Manitoba. Irrigation is also used in Ontario and the Maritimes for frost control (primarily of fruit crops in the Annapolis Valley). Most of the water withdrawn by agriculture ends up evaporating. Thus, very little of the water withdrawn is put back into the system, agriculture use is thought to be highly consumptive.

Mining
This category includes metal mining, non-metal mining, and the extraction of fossil fuels. Water is used by the mining industry to separate ore from the rock, to cool drills, to wash the ore during production, and to carry away unwanted material.

Water is also used to extract and process oil that cannot be recovered by conventional drilling methods. Deep well injection, for example, involves pumping water into wells under pressure to force the oil to the surface.

Although the mining industry had a gross use almost as great as agriculture, mining accounted for only mining accounted for only 1% of all water withdrawals in 1996. This was the smallest withdrawal use, but mining recirculates its water intake to a greater extent than any other sector.

A Brief Examination of Six Instream Water Uses

Instream uses cannot be measured in terms of quality because the water used is not removed from its natural environment. Instead, instream uses are described by certain characteristics of the water or by the benefits they provide to us and the ecosystem.

Flow rates and water levels are very important factors for instream water users. When these conditions are changed by a dam, for instance, it is easy for conflicts between users to arise. The most common conflict that arises between instream users is between hydroelectric developers and other users (with respect to aquatic life, wildlife, water supply and water transportation). Storage of the spring freshet³ removes the natural variability of streamflows. The life processes of aquatic species may depend on this variability, in particular, the highly productive ecosystems of deltas, estuaries and wetlands. To make the best use of our water, all needs must be carefully assessed and considered.

Hydroelectric Power Generation
This water use provides the principal source of electricity in Canada today. Billions of dollars have been invested in its development. With large undeveloped hydroelectric sites still available in Quebec, Newfoundland, Manitoba, British Columbia and the Territories, this form of energy development is expected to retain its prominent position for years to come. However, the potential of these type of developments to affect the environment and human culture makes their development increasingly difficult and costly to plan and to build.

Water Transport
Inland waterways in Canada have historically played a major role in getting Canadian goods and raw materials to market. Some traditional uses, such as log driving, have now disappeared. However, water transport is still the most economical means of moving the bulky raw materials which are our main exports: wheat, pulp, lumber, and minerals. The main transportation waterways of Canada include the St. Lawrence River, which allows passage of ocean-going ships from the Atlantic Ocean deep into the heart of North America (almost as far as the prairie wheat fields); the Mackenzie River, a vital northern transportation link; and the lower Fraser River on the Pacific Coast. Cargo in the hundreds of millions of tonnes is transported along these routes each year. Reliable and predictable lake and river levels are very important to this industry.

Freshwater Fisheries
Canada is blessed with hundreds of thousands of freshwater lakes and rivers, and provides some of the most spectacular sport fishing in the world. In 1995, over 4.2 million Canadians and visiting anglers took advantage of this fact, spending $7.4 billon in the process. In 1997, the freshwater fishing industry contributed $71 million to the GDP and employed 3 500 people. Moreover, coastal rivers provide spawning grounds for salmon and other fish populations which support major saltwater fisheries.

Wildlife
Many wildlife species live in, on, or near water, and require access to it throughout their lives. Other species may not use water as their primary habitat, but it is nonetheless essential to their well-being. Watching, photographing, and studying wildlife are all popular forms of recreation for Canadians. About 19% of Canadians aged 15 years and over participated in these activities as the main or as a secondary reason for their nature-related trip, according to a 1996 survey, and spent about $1.3 billion that year on them. Hunting (controversial as it may be) attracted over one in twenty Canadians and accounted for about $800 million of wildlife-related spending. And these activities are all on the rise, according to statistics compiled by Environment Canada and provincial Departments of Natural Resources.

Recreation
Canadians value opportunities for outdoor recreation and in recent years have sought the outdoors as never before. Swimming, boating, canoeing, fishing, and camping activities allow us to experience the beauty of our lakes and rivers. While not all outdoor recreation requires water, the presence of water tends to enhance the experience. Expenditures on water-related recreational activities and tourism also contribute billions of dollars each year to the national economy.

Waste Disposal
It has been convenient for water users to view lakes, rivers and oceans as logical receivers of human and industrial wastes. While water is capable of diluting and "digesting" society's wastes to some degree, there are limits to what even the largest body of water can absorb. The extent to which instream processes can accept contaminants depends on factors such as the nature of the contaminant, how much of it there is compared with the volume of water, how long the contaminant stays in the water, the temperature of the water, and the rate of flow. Many of our waterways are now overloaded with wastes. This problem can best be resolved by increasing regulation and/or monitoring.

Activities

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Wind and Water

Grades 4, 5, 6 – Science

Purpose

A windmill uses the force of the wind to do useful work. Water wheels turn the energy of running water into useful power. Before the first steam engines were invented, windmills and water wheels were almost the only machines that were not powered by human or animal muscles. Farmers often used them to grind corn and pump water.

When engines fuelled by coal and oil came along, windmills and water wheels began to disappear. However, they are becoming popular once more. Today, we are more aware of the pollution caused by burning fossil fuels such as coal and petroleum. Wind and water power are clean and quiet sources of energy. Water wheels can be built wherever there is fast-flowing water that will turn the blades of the wheel.

Most modern water wheels are complicated machines that are used to make electricity. They are called hydroelectric turbines, and the electricity they produce is hydroelectricity. Hydroelectric turbines are usually built along big rivers or in dams, where water is forced to pass through a turbine in order to get out of the reservoir. Electricity can even be generated in coastal areas, by the movement of the tides through a turbine.

Materials

• cork
• funnel
• scissors
• modelling clay
• plastic tube
• tape
• stiff plastic
• two toothpicks
• glass dish
• sharp knife (teacher assistance required)
• plastic 2 litre pop bottle
• nail

Procedure

Create the turbine
Cut four slits lengthwise in the cork, evenly spaced. Cut four pieces of stiff plastic. Make all pieces the same length as the cork and fit the pieces of plastic into the slits. Make sure the blades fit snugly into the cork.

Create the turbine assembly
Using the nail, pierce two holes in opposite sides of the 2 litre bottle. Cut the bottom off of the bottle. Make sure the edge is straight, so that the bottle can stand upright. Push a toothpick into one end of the cork, then fit it into one hole in the bottle. Push the other toothpick through the other hole and into the cork. The water wheel must be able to spin easily in its cradle.

Create the sluice
Push the narrow end of the funnel into one end of the piece of plastic tubing. Wind tape around the joint to hold the funnel and the tubing tightly together.

Place the bottle in the dish. Fit the tube (with the funnel attached) into the neck of the bottle, making sure that the stream of water will hit the plastic blades of the wheel (hold the funnel at a higher level than the bottle neck opening so that the water will run downhill).

In a hydroelectric power station, water falling down a pipe (the plastic tubing) from a dam (the funnel) spins the blades of the turbine (the water wheel). The turbine drives a generator that makes electricity.

Predict the results of a change in the rate of flow
Raise the funnel so that it is straight above the opening of the bottle. Ask the students to pour water into the funnel at this height, and to predict any change to the motion of the water wheel blades. The water moves faster because it is falling a greater distance, and, as a result, the water wheel moves faster.

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Lift a Load with Water

Grades 4, 5, 6 – Science

Purpose

Using water to lift a heavy weight is known as hydraulic lifting. Very powerful machines allow workers to pull, press or lift things that they wouldn't ordinarily be able to. Hydraulics greatly increase the force produced by these machines.

In hydraulic machines (like earth movers), pipes carry a liquid from a pump to cylinders where the liquid pushes out pistons with great force. In an earth mover, pistons drive the earth moving shovel into the ground and let the machine raise a heavy load of soil. The mechanics of this hydraulic movement are demonstrated in this activity. When the funnel is raised above the level of the book, and weight of the water in the tube pushes water into the balloon. The swelling balloon then exerts enough pressure to push the heavy book upwards.

Materials

• rubber band
• plastic tube
• tape
• heavy book
• plastic bottle (500 ml)
• water
• balloon
• scissors
• funnel
• small soup can

Procedure

Fit the neck of the balloon over the end of the tube and seal the joint tightly with tape.

Cut the top off the bottle, making a hole in the side, near the base of the bottle.

Push the balloon through the hole in the side of the bottle, so that the plastic tube is sticking out through the side.

Tape the funnel firmly to the "free" end of the tube.

Place the can inside the bottle, on top of the balloon. The sides of the bottle should extend just past the top of the can. Lay the heavy book on top of the bottle.

Lift the funnel so that it is raised about six inches or more above the upper rim of the bottle. Pour some water into the funnel, so that it runs down the tube and into the balloon. As the balloon swells, the can on top of the balloon is raised, and so is the book!

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Make It Sink – Then Float!

Grades 4, 5, 6 – Science

Purpose

A huge ship floats on water, even though it is very heavy. Yet a small, light object – such as a marble – will sink. Why? The weight of objects alone does not suggest whether or not something will sink or float. Whether or not something will float depends on how much water it displaces, or pushes aside.

Have you ever noticed the marks painted low on the hulls of ships? These marks show safe loading levels. An overloaded ship settles too low in the water, and risks sinking.

Materials

• modeling clay
• marbles
• a glass tank or large (wide) bowl of water

Procedure

Drop marbles into the water. Notice that they quickly sink to the bottom of the container.

Ask the students to predict what will happen if the clay is dropped into the container.

Roll the clay into a ball, and drop it in. The clay will also sink. Just like the marbles, it does not displace much water.

Remove the marbles and the clay ball. Shape the clay to make a flat-bottomed boat (or a plate-like form). Float the clay in the container of water. This new shape displaces more water than the ball form did: more water has been displaces, and it pushes with more force, supporting the clay boat, making it float.

Add the marbles to the clay boat – they are its "cargo". The boat will settle lower in the water, but displaces more water and still floats.

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Notes:

1. The energy potential of a major river system is enormous. A single major system spends as much energy (every half hour) falling from its mountain sources to sea level as was released by the explosion of the Hiroshima bomb.
2. Environment Canada statistic.
3. A freshet is a high river flow caused by rapidly melting snow.

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