Week 31 - Human Activities Affect Aquatic Environments


Lesson 11

Read pages 393 - 399

Lesson 11: How Humans Use Water

Water is such an important part of our lives. We need to consider our water supply and the effect that we as humans have on that water supply. We use water to produce our food, for industry and for our day to day living. How does this use affect the overall water supply? This lesson will address this question.

In this section, we are going to take a look at three of the major human uses of water and how that use affects the water quality and supply. We will examine agricultural, industrial and domestic use.
Agricultural Use


As the earth's population increases, efficient food production becomes more and more important. And of course, water is essential to grow both plants and animals that serve as our food source. To increase the efficiency of food production, practices like fertilization and irrigation are used. These work to grow better crops, but sometimes have a negative effect on our potable water supply. Potable water refers to water that is safe for human consumption.
Fertilizers containing nitrates and phosphates grow better plants, but have a bad effect when they reach bodies of water through runoff. These high nutrient levels increase the algae growth in lakes. Eutrophication is a process by which a lake changes to a shallow pond as dead organic matter falls to the bottom of the lake. So fertilizer and cattle feedlot runoff increases the rate of eutrophication because of the high level of nutrients entering the water.
Irrigation has the effect of lowering the water table when too much water is taken out. In addition, Irrigation water can speed up the dissolving of salts in the soil and leave them on the surface of the soil. Most plants do not grow in salty conditions.

Industrial Use


We use water in many of the industries that produce products that we use on a daily basis - some examples include steel, paper and plastic production. These processes produce some toxic (poisonous) by products that are sometimes released into our water system. An example of such a toxic substance would be PCB's that were accidentally released into the water system. PCB's were responsible for killing many water living organisms. Another pollutant involves the production of acid rain. Many industrial process produce nitrogen and sulfur oxides. When these combine with rain water, they produce rain that is acidic. Winds may blow these acid rain producing materials far from the factories and forests and lakes are damaged - once again affecting the water supply.


Domestic Use
The water we use on a day to day basis is referred to as 'domestic use'. In Canada, we take for granted that we will have clean running water in our homes. However, we are also part of the problem when it comes to keeping a good water supply. We produce waste as part of living and this sewage must be disposed. The wastes we flush away must be treated in sewage systems before the water can rejoin the water cycle. Improper treatment will contaminate our water. When we dispose of our garbage in land fill sites, toxic materials can enter the groundwater and so care must be exercised here.

Check out this news story from 2006!

Water supply crisis looms over Prairies: study

Updated Mon. Apr. 3 2006 11:19 PM ET

Canadian Press


In this 1998 photo, a marker shows where the toe of the Athabasca Glacier was in 1948. Over the next 50 years, the glacier receded about two kilometres. (CP PHOTO/Bill Graveland)

Section: Water Supply Crisis Article


OTTAWA - Canada's Prairies will face an unprecedented water crisis in coming years due to declining river flows and growing water usage -- especially in processing Alberta's vast oil sands, says a new study.

Summer flows in Prairie rivers are already 20 to 80 per cent lower than in the early part of the 20th century, say Alberta researchers David Schindler and W.F. Donahue.

Worst affected is the South Saskatchewan River, whose summer flows have been reduced by 84 per cent, according to the study published in Proceedings of the National Academy of Sciences.

All the major Prairie rivers are fed by melting snow and ice in the Rockies, but the glaciers and snowpack have been receding due to climate warming.

Weather records in the Prairies show a warming of one to four degrees C in the past 80 to 118 years, and half the weather stations receive substantially less precipitation than a century ago.

The study says that Alberta is the most vulnerable to water shortages because of population growth, extensive use of irrigation and the rapid growth of the oil industry.

"The projected use of water for the oil sands could be as high as 45 cubic meters a second, which would be about half of the low flow of the Athabaska in most of the years of the last 15 or 16,'' said Schindler.

Currently the oil sands consume three to six barrels of water per barrel of oil produced.

The wetlands in northern Alberta area already showing negative effects of declining water supply, but large oil sands projects continue to be proposed and approved, says the study.

Alberta also accounts for almost three-quarters of Canada's irrigation agriculture, and for intensive livestock operations with 6.4 million cattle and 1.8 million hogs.

"If the trends described above continue, the combination of climate warming, increases in human populations and industry, and historic drought is likely to bring an unprecedented water crisis in the Western Prairie Provinces,'' says the report.

When will the crisis hit?

"The first time we'll see it will be when our high water demand corresponds with those prolonged droughts that we've seen in every century before the 20th,'' says Schindler.

"We need to look hard at how we use water ... and the other (solution) is to protect our watersheds by leaving the wetlands and riparian (shore) areas intact.

"We really need comprehensive watershed planning ... but when I see how fast development and the loss of water flows are proceeding, I really wonder if we're going to get there on time.''

Now ... check out this news story from 2015!

70% of glaciers in BC, Alberta will melt by 2100: Study

Updated: Monday, April 6, 2015 08:13 PM EDT


Mount Robson, the highest peak in the Canadian Rockies. (FOTOLIA)

Section: Water Supply Crisis Article

VANCOUVER — A study released Monday predicts 70% of Western Canada's glaciers will have disappeared by the end of the century.

Water supply, freshwater ecosystems and energy production are all at extreme risk in B.C. and Alberta's Rocky Mountains, the researchers found.

The study, published in Nature Geoscience, found the drier interior could lose up to 90% of its glaciers. Glaciers in the wetter coastal mountains in northwestern B.C. are expected to shrink by about 50%.

Most of the ice that will be left by 2100 may be in the northwest corner of B.C. Currently, there are about 17,000 glaciers in B.C. and Alberta.

The group, comprised of researchers from the University of B.C., University of Northern B.C., University of Iceland and Pacific Climate Impacts Consortium, started their work in 2006 and used a range of greenhouse gas emission scenarios used by the Intergovernmental Panel on Climate Change in the latest assessment of the state of the climate system.

Garry Clarke, UBC professor in the Department of Earth, Ocean and Atmospheric Sciences, said they chose to paint a picture of glaciers by the year 2100 as it's a human lifetime away.

"If you tell people how things will be 500 years from now, you don't get their attention," he said.

"It's a middle ground. It's a little bit longer than a human lifetime, but people won't totally bail out of their responsibility for the immediate future."

The glaciers play a vital role in hydroelectric power production and contribute to local tourism, agriculture and the water supply, Clarke said.

He said the glaciers are the best evidence for climate change because deniers often use weather as an argument point.

"You'll see people bringing snowballs into the Senate claiming global warming is a hoax," he said.

"The glaciers don't respond to weather, they don't care about this argument. … They're telling us the climate is worse for them, it's getting warmer and the glaciers are shrinking."

Clarke said he hopes the study will sharpen the tools for other countries in central Asia and America, where a larger amount of people will be affected by the melting glaciers.

Exercise 4.1A: Water Usage Definitions




Exercise 4.1B: Your Water Usage



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