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