EESA10H3 Lecture Notes - Lecture 3: Surface Runoff, Lake Ontario, Tap Water

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28 Jun 2012
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Lecture 3: Waterborne Hazards and Human Health
Liquid natural capitol
Water generally is a liquid capitol, natural capitol
Why is it natural? Water is available everywhere in nature, we are surrounded by water
Even our body is mostly consisted of water
Earth is a water planet – 71% of our surface is covered with water
Not all of this water is available for us for our consumption
Why? Mostly salty water – we are surrounded by huge oceans and huge seas
Not much fresh water that we can use for human consumption and animal consumption
Why is water so important? No living species (animals, plants, or humans) can survive and live
without water
We always think about drinking though water is not just for drinking
Everything in household from cleaning to cooking, industrial purposes, agriculture (for watering
plants and crops)
There is a science called geomorphology that discusses sculpting the Earth’s surface
Water is one of the factors that changes the shape of planet Earth – this is called water erosion
One of the types of erosion is water soil erosion - changes, moving of the soil by water – water
streams, surface runoff
Moderating climate – mild winter, hot summers (not that hot)
Water is a universal solvent – solve many different chemicals, same is the thing in nature
Water is involved in dissolving and diluting particles – can be good and something that we might not
want
Water also dilutes wastes and pollutants – what happens is move water together with water
stream/flow and reach rivers, lakes, ponds, oceans
Withdrawal- total amount of water removed from a river, lake or aquifer for any purpose
Some may be returned to the source for reuse
Use about 54% of the world's reliable runoff of surface water and could be using 70-90% by 2025
How much fresh water is available?
Not much fresh water is available on Earth
97.4% of all water is found in oceans and saline lakes
2.6% in fresh water is available
Of the 2.6% in fresh water most of it is captured as ice caps and glaciers (1.984%)
Water from ice caps and glaciers is not readily available (might be if global warming continues)
Groundwater composes of a significant amount of the fresh water
Groundwater is available for us but we need to pump it out to use it and consume it and also not use it
more than it is replenished
There is only 0.014% of readily available fresh water
Of this, 0.007% is found in lakes, 0.005% as soil moisture, some significant amount of water is in
atmosphere as water vapour and some as biota (all living organisms)
There are huge amounts of water stored in leaves and vegetation
World’s Problems
Some areas have lots of water but the largest rivers are far from agricultural and population
centers
Lots of precipitation arrives during short period but cannot be collected and stored
Shrank of lakes and rivers
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How do we use the world’s fresh water?
There is a comparison between three countries – Canada, U.S. and China
There is a significant difference in the use of fresh water between these three countries
We are most interested in Canada – 64% of the fresh water is used for power plant cooling, 15% in
industry, 12% in public and 9% in agriculture
If you look at the graph of the U.S. much more water is used in the agricultural sector (41%)
United States uses much more water for irrigation in agriculture; China uses even much more (61%)
More specifically how do we use water in households? Too much water is used for conventional use –
flushing toilet (30%), showering (35%), laundry (20%), drinking 10% and cleaning (5%)
Hydrological poverty
Canada has plentiful water available but what about the people in some areas of the world
People in many developing countries just don’t have enough water for basic things such as drinking
or cooking
One out of six people do not have regular access to clean water (safe water to drink)
In many areas such as North Africa and Western Asia people travel far distances to just get a couple
of litres of water (they spend half of the day doing it)
They need to do it just to survive (often use polluted water because that is all they can find)
As a result of this diarrheal deaths is very common in developing countries
It is the number one cause of death in children younger than five years old
The biggest risk – 2 million kids die every year due to diarrheal death
Adults are also under high risk but definitely children are at a huge risk
Water and Your health
We are in desperate need for help – drinking water and swimming water
Drinking Water
It is our right to know what it is that we drink – what other chemicals that we have in a glass of water
that we consume today
Our municipals must provide us with record – they are checking our tap water everyday
Provide us with annual reports on local drinking water quality
On water bottles it says naturally pure water – water cannot be 100% pure because water naturally has
to have some minerals (no such thing as pure water
We need calcium, potassium, magnesium, sodium and salts
Distillate water is water without salts – our body needs salts
Our tap water comes from Lake Ontario, an example of surface water
Surface water – in urban areas mostly from rivers, lakes and reservoirs
Ground water can also be used for water supply – wells are very common in rural areas
Ground water reservoirs can be very small or extremely huge
There is one ground water reservoir in the U.S. thousands of metres deep underground that runs in 6
states
If we withdraw all this water more than can be naturally replenished that water reservoir will shrink
and it will not last forever
How is drinking water treated?
What do the municipalities do after they take water from rivers, lakes and reservoirs?
They need to clean it, it is not for drinking
First they leave water in tanks to settle down – it is easier later to purify
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