GEOG 101: Day 13

Fresh Water

New film just released in the theatres: “Watermark” by Jennifer Baichal and Edward Burtynski; see also films by Paul Manley, and “Blue Gold,” “Water Wars,” etc.

Housekeeping Items• I hope you had a good Thanksgiving weekend.• Today is the due date for the alternative assignment

(that replaces the mid-term).• I will hand back as many outlines today as possible.• Other announcements?• One announcement that I have is that the Geography

Department and the North Island chapter of Planning Institute of BC are co-sponsoring the 8th Annual Urban Issues Film Festival on campus on Friday, November 8th on the broad theme of “water and planning.” Volunteers are always welcome and we are having an organizing meeting in the library portion of Jumping Java today at 4 p.m.

© 2010 Pearson Education Canada

12Freshwater Systems

and Water Resources

PowerPoint® Slides prepared by Stephen Turnbull

Copyright © 2013 Pearson Canada Inc.

12-3

Upon successfully completing this chapter, you will be able to

• Explain the importance of water and the hydrologic cycle to ecosystems, human health, and economic pursuits

• Delineate the distribution of fresh water on Earth• Describe major types of freshwater ecosystems • Discuss how we use water and alter freshwater systems• Assess problems of water supply and propose solutions to

address depletion of fresh water• Assess problems of water quality and propose solutions to

address water pollution• Explain how waste water is treated

12-4

• Canadians fear we will place our sovereignty at risk is we allow large-scale diversions of fresh water

• Once they start, they will be impossible to stop• Some view water as a marketable commodity, others say we should

not consider exporting it to those have mismanaged theirs.• Canada’s fresh water is protected as each province and territory

prohibits bulk water exports“The wars of the twenty-first century will be fought over water.”

– World Water Commission Chairman Ismail Serageldin

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Freshwater Systems

12-6

Freshwater systems• Water may seem abundant, but drinkable water is rare• Freshwater = relatively pure, with few dissolved salts

– Only 2.5% of Earth’s water is fresh, most is tied up in glaciers and ice caps. Of the 21% that is not, only 53% is in rivers, lakes or groundwater.

12-7

Rivers and streams wind through landscapes

• Water from rain, snowmelt, or springs forms streams, creeks, or brooks

• These merge into rivers, and eventually reaches the ocean– Tributary = a smaller

river slowing into a larger one

– Drainage basin or watershed = the area of land drained by a river and its tributaries

12-8

Rivers and streams wind through landscapes (cont’d)

• If there is a large bend in the river, the force of the water cuts through the land – Oxbow = an extreme bend

in a river– Oxbow lake = the bend is

cut off and remains as an isolated, U-shaped body of water

12-9

Rivers and streams wind through landscapes (cont’d)

• Floodplain = areas nearest to the river’s course that are flooded periodically– Frequent deposition of silt makes floodplain soils

fertile• Riparian = riverside areas that are productive and

species-rich• Water of rivers and streams hosts diverse

ecological communities

12-10

Wetlands include marshes, swamps,and bogs

• Wetlands = systems that combine elements of freshwater and dry land

• Freshwater marshes = shallow water allows plants to grow above the water’s surface

• Swamps = shallow water that occurs in forested areas– Can be created by beavers

• Bogs = ponds covered in thick floating mats of vegetation – A stage in aquatic succession

12-11

Wetlands include marshes, swamps, and bogs (cont’d)

• Wetlands are extremely valuable for wildlife• They slow runoff

– Reduce flooding– Recharge aquifers– Filter pollutants

• People have drained wetlands, mostly for agriculture– Southeastern (Potholes region) Canada has lost more

than half of their wetlands

12-12

Lakes and ponds are ecologically diverse systems

• Lakes and ponds are bodies of open, standing water• Littoral zone = region ringing the edge of a water

body • Benthic zone = extends along the entire bottom of

the water body – Home to many invertebrates

• Limnetic zone = open portions of the lake or pond where the sunlight penetrates the shallow waters

• Profundal zone = water that sunlight does not reach – Supports fewer animals because there is less oxygen

12-13

12-14

Lakes and ponds are ecologically diverse systems (cont’d)

• Oligotrophic lakes and ponds = have low nutrient and high oxygen conditions

• Eutrophic lakes and ponds = have high nutrient and low oxygen conditions

• Eventually, water bodies fill completely in through the process of succession

• Inland seas = large lakes (such as the Great Lakes and, formerly, the Aral Sea that hold so much water, their biota is adapted to open water

12-15

Groundwater plays key roles in the hydrologic cycle

• Groundwater = precipitation that does not evaporate, flow into waterways, or get taken up by organisms

• Aquifers = Porous sponge-like formations of rock, sand, or gravel that hold groundwater

• Zone of aeration = spaces are partially filled with water

• Zone of saturation = spaces are completely filled with water– Water table = boundary

between the two zones• Aquifer recharge zone = any area

where water infiltrates Earth’s surface and reaches aquifers

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A typical aquifer

12-17

Groundwater plays key roles in the hydrologic cycle (cont’d)

• Confined or artesian = water-bearing, porous rocks are trapped between layers of less permeable substrate (i.e., clay) – Is under a lot of pressure

• Unconfined aquifer = no upper layer to confine it– Readily recharged by surface water

• Groundwater becomes surface water through springs or human-drilled wells

• Groundwater may be ancient: the average age is 1,400 years

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Water is unequally distributed across Earth’s surface

• Many areas with high population density are water-poor and face serious water shortages

12-19

Climate change will cause water problems and shortages

• Climate change will affect the hydrologic cycle: – Shift northward in mid-latitude rain belt– Earlier snowmelt and spring runoff– More evapotranspiration– Drier summers in the interior continental region

• Additional impacts:– Warmer rivers (impacting fish)– Lower water levels in Great Lakes– Higher ocean water levels

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How We Use Water

12-21

How we use water• We have achieved impressive engineering

accomplishments to harness freshwater sources– 60 % of the world’s largest 227 rivers have been

strongly or moderately affected – Dams, canals, and diversions

• Consumption of water in most of the world is unsustainable– We are depleting many sources of surface water and

groundwater– One-third of the world’s people are already affected

by water scarcity

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Water supplies houses, agriculture, and industry

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Water supplies houses, agriculture, and industry (cont’d)

• Consumptive use = water is removed from an aquifer or surface water body, and is not returned

• Non-consumptive use = does not remove, or only temporarily removes, water from an aquifer or surface water– Electricity generation at hydroelectric dams

12-24

We have erected thousands of dams• Dam = any obstruction placed in a river or

stream to block the flow of water so that water can be stored in a reservoir– To prevent floods, provide drinking water, allow

irrigation, and generate electricity– 45,000 large dams have been erected in more than

140 nations• Only a few major rivers remain undammed

– In remote regions of Canada, Alaska, and Russia

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A typical dam

12-26

Benefits and drawbacks of dams

• Benefits:– Power generation– Emission reduction– Crop irrigation– Drinking water– Flood control– Shipping– New recreational

opportunities

• Drawbacks:– Habitat alteration– Fisheries declines– Population

displacement– Sediment capture– Disruption of flooding– Risk of failure– Lost recreational

opportunities12-27

China’s Three Gorges Dam is the world’s largest

• 186 m high and 2 km wide, completed in 2006• When filled it will be as long as Lake Superior• It has cost $25 billion to build, flooded 22 cities

and the homes of 1.24 million people, submerged 10,000 year-old archaeological sites, productive farmlands, and wildlife habitat, and causing erosion below the dam

• Some fear pollutants will also be trapped in the reservoir, making water undrinkable

• Two films about: “China’s Three Gorges Dam” and Still Life.”

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Some dams are now being removed• Some people feel that the cost of dams outweighs their

benefits• Rivers with dismantled dams

– Have restored riparian ecosystems– Reestablished fisheries– Revived river recreation

• In Canada only a few dams have been decommissioned but 500 dams have been removed in the U.S.

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“YOSEMITE NATIONAL PARK, Calif. — An environmental artist with the skills of a mountain climber painted a giant crack down the face of Hetch Hetchy Reservoir dam, park officials said Monday. "It was really a work of art--it wasn't just graffiti," said Dean Coffey, general manager with the Hetch Hetchy Water and Power District, which provides water to San Francisco and surrounding communities. ‘Whoever did it has a lot of pride.’”

Dikes and levees are meant to control floods

• Flooding is a normal, natural process– Floodwaters spread nutrient-rich sediments over large

areas• Floods also do tremendous damage to property• Dikes and levees (long, raised mounds of earth)

along the banks of rivers hold rising waters in channels

• Levees can make floods worse by forcing water to stay in channels and overflow

12-30

We divert – and deplete – surface water to suit our needs

• Diversion has drastically altered the river’s ecology

• What water is left in the Colorado River after all the diversions comprises just a trickle into the Gulf of California and Mexico

12-31

We divert – and deplete – surface water to suit our needs (cont’d)

• Aral Sea - once the fourth-largest lake on Earth

– lost over 80% of its volume in 45 years from diversion

• Consequences– Lost 60,000 fishing jobs– Pesticide-laden dust from

the lake bed is blown into the air

– The cotton cannot bring back the region’s economy

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We divert – and deplete – surface water to suit our needs (cont’d)

People may have begun saving the northern part of the Aral Sea

12-33

Inefficient irrigation wastes water• Today, 70% more water is withdrawn for

irrigation than in 1960– The amount of irrigated land has doubled– Crop yields can double

• Only 45% of water is absorbed by crops via “flood and furrow” irrigation

• Overirrigation leads to waterlogging, salinization, and lost farming income

• Most national governments subsidize irrigation

• Water mining = withdrawing water faster than it can be replenished

12-34

Areas where water use exceeds supply; will get worse with climate change

12-35

Flood protection at what cost?

In May 2011, during record high-water levels on the Assiniboine River, the government of Manitoba deliberately breached a dike near Portage-la-Prairie, with the goal of releasing pressure in the Portage Reservoir and averting a much larger, uncontrolled flood. The controlled release put 150 homes and a considerable area of farmland at risk. In the end, the controlled breach worked, and no homes in the threatened area were significantly harmed.

weighing

the issues

12-36

Flood protection at what cost (cont’d)?

A similar situation occurred during the Red River Floodway of 1997, during which the Red River Floodway diverted floodwater to protect the city of Winnipeg, but perhaps at the cost of flooding in smaller communities such as St. Agathe. Both events caused significant stress for those in the path of diverted floodwaters. • If you were a decision maker in Manitoba, would you have reached the same decision?•Is it worthwhile to protect certain areas, even if it means risking others? • What might you do to compensate those who were at risk?

weighing

the issues

12-37

Wetlands have been drained for a variety of reasons

• Promote settlement and farming• Seen as useless “swamps”• Ramsar Convention in 1971

– Global concern for wetland loss and degradation– Promotes local, regional, and national actions

and international cooperation• 90% of original wetlands in southern Canada have

been lost

12-38

We are depleting groundwater• Groundwater is easily depleted

– Aquifers recharge slowly– 1/3 of world population relies on groundwater

• As aquifers become depleted– Water tables drop– Salt water intrudes in coastal areas– Sinkholes = areas where ground gives way

unexpectedly– Some cities (Venice, Mexico City) are slowly sinking– Wetlands dry up

12-39

Our thirst for bottled water seems unquenchable

• Canadians’ use of bottled water only surpassed by U.S.• University-educated households were shown to be less

likely to consume bottled water• Average capital use in 2003 was almost 50 L of bottled

water• Most bottled water is nothing more than tap water,

sometimes with additional filtering or other treatment• Canada’s Food and Drug Act does not require a

manufacturer to obtain a licence to bottle water12-40

The price of a litre

• Do you drink bottled water? Why? • Do you think it is safer than municipal water? Do you prefer the taste?• What do you pay for a litre of bottled water? What do you pay for a litre of gas at the pump? • What do you think should be reflected in these prices? • What price do you think was paid for the water by the company that bottled it? • What about the source of the water you consume— is it groundwater and, if so, is its source adequately protected? • And what about the plastic waste that is generated?

weighing

the issues

12-41

Will we see a future of water wars?• Freshwater depletion leads to

shortages, which can lead to conflict– 261 major rivers cross national borders– Water is a key element in hostilities

among Israel, Palestinians, and neighboring countries

• Many nations have cooperated with neighbors to resolve disputes– India, Pakistan, Bangladesh, Bhutan,

and Nepal

12-42

Solutions to Depletion of Fresh Water

12-43

Solutions can address supply or demand

• We can either increase supply or reduce demand• Lowering demand

– Politically difficult in the short term – Offers better economic returns– Causes less ecological and social damage

• Increasing supply– Water can be transported through pipes and aqueducts– It can be forcibly appropriated from weak communities

12-44

Desalinization “makes” more water• Desalinization = the removal of salt from seawater

or other water of marginal quality– Distilling = hastens evaporation and condenses the vapor– Reverse osmosis = forces water through membranes to

filter out salts• Desalinization facilities operate mostly in the arid

Middle East• It is expensive, requires fossil fuels, and produces

concentrated salty water

12-45

Agricultural demand can be reduced• Look first for ways to decrease agricultural

demand – Lining irrigation canals– Low-pressure spray irrigation that spray water

downward– Drip irrigation systems that target individual plants– Match crops to land and climate– Selective breeding and genetic modification to raise

crops that require less water

12-46

We can lessen residential and industrial water use in many ways

• Eat less meat (1 kg of beef = 13-15,000 litres)• Install low-flow faucets, showerheads, washing

machines, and toilets• Use automatic dishwashers instead of washing

dishes by hand• Water lawns at night, when evaporation is

minimal, or replace lawn with native plants • Xeriscaping = landscaping using plants adapted

to a dry environment12-47

• Shift to processes that use less water– Wastewater recycling (separating greywater and

brown water, and re-using former)– Excess surface water runoff used for recharging

aquifers– Patching leaky pipes– Auditing industries– Promoting conservation/education

12-48

We can lessen residential and industrial water use in many ways

Economic approaches to water conservation are being debated

• End government subsidies of inefficient practices– Let the price of water reflect its true cost of extraction

(the tar sands use huge amounts of freshwater and contaminate the water that is released back into river systems)

• Industrial uses are more profitable than agricultural• Privatization of water supplies

– May improve efficiency– Firms have little incentive to provide access to the poor

• Decentralization of water control may conserve water– Shift control to the local level

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Freshwater Pollution and Its Control

12-50

Freshwater pollution and its control• Water for human consumption and other

organisms needs to be…

– Disease-free– Non-toxic

• Half of the world’s major rivers are seriously depleted and polluted– They poison surrounding ecosystems– Threaten the health and livelihood of people

• The invisible pollution of groundwater has been called a “covert crisis”

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Water pollution takes many forms• Pollution = the release of matter or energy into

the environment that causes undesirable impacts on the health and well-being of humans or other organisms – Nutrient pollution– Pathogens and waterborne diseases– Toxic chemicals– Sediment– Thermal pollution

12-52

Water pollution takes many forms (cont’d)

• Nutrient pollution from fertilizers, farms, sewage, lawns, golf courses– Leads to eutrophication (is a natural process but

excess nutrients increase the rate)• Solutions

• Phosphate-free detergents• Planting vegetation to increase nutrient uptake• Treat wastewater• Reduce fertilizer application

12-53

Water pollution takes many forms (cont’d)

• Pathogens and water borne diseases– Enters water supply via inadequately treated human

waste and animal waste via feedlots– Causes more human health problems than any other

type of water pollution– Fecal coliform bacteria indicate fecal contamination of

water• The water can hold other pathogens, such as

giardiais, typhoid, hepatitis A

12-54

Water pollution takes many forms (cont’d)

• Pathogens and water borne diseases– 1.1 billion people are without safe drinking water– 2.6 billion have no sewer or sanitary facilities– An estimated 5 million people die per year– Solutions:

- Treat sewage- Disinfect drinking water- Public education to encourage personal hygiene- Government enforcement of regulations

12-55

Water pollution takes many forms (cont’d)

• Toxic chemicals– From natural and synthetic sources– Effects:

• Poisoning animals and plants • Altering aquatic ecosystems • Poor human health

– Solutions:- Legislating and enforcing more stringent

regulations of industry- Modify industrial processes- Modify our purchasing decisions

12-56

Water pollution takes many forms (cont’d)

• Suspended matter– Sediment can impair aquatic ecosystems

• Clear-cutting, mining, poor cultivation practices

– Effects:• Dramatically changes aquatic habitats• Fish may not survive

– Solutions: • better management of farms and forests• avoid large-scale disturbance of vegetation

12-57

Water pollution takes many forms (cont’d)

• Thermal pollution– Warmer water holds less oxygen

• Dissolved oxygen decreases as temperature increases • Industrial cooling heats water• Removing streamside cover also raises water

temperature– Water that is too cold causes problems

• Water at the bottom of reservoirs is colder• When water is released, downstream water

temperatures drop suddenly and may kill aquatic organisms

12-58

Water pollution comes from point and non-point sources

• Point source water pollution = discrete locations of pollution– Factory or sewer pipes

• Nonpoint source water pollution = pollution from multiple cumulative inputs over a large area– Farms, cities, streets, neighborhoods

12-59

Freshwater pollution sources

12-60

Scientists use several indicators of water quality

• Scientists measure properties of water to characterize its quality– Biological indicators: presence of fecal coliform

bacteria and other disease-causing organisms– Chemical indicators: pH, nutrient concentration,

taste, odor, hardness, dissolved oxygen– Physical indicators: turbidity, color, temperature

12-61

Groundwater pollution is a serious problem

• Groundwater is increasingly contaminated, but is hidden from view– Difficult to monitor– Out of sight, out of mind– Retains contaminants for decades and longer– Takes longer for contaminants to breakdown in

groundwater because of the lower dissolved oxygen levels

• DDT is still found in aquifers in North America although it was banned 40 years ago

12-62

There are many sources of groundwater pollution, including some natural sources• Some toxic chemicals occur naturally

– Aluminum, fluoride, sulfates• Pollution from human causes

– Wastes leach through soils– Pathogens enter through improperly designed

wells– Hazardous wastes are pumped into the ground– Underground storage septic tanks may leak

12-63

There are many sources of groundwater pollution, including some natural sources (cont’d)

• Agricultural pollution– Nitrates from fertilizers– Pesticides were detected in more than half of the

shallow aquifers tested– Walkerton – E. coli in water supply

• Manufacturing industries and military sites – for instance, Hanford, WA – have been heavy polluters

12-64

Legislative and regulatory efforts have helped reduce pollution

• Pollution legislation is enacted and enforeced at the provincial level

• Federal government sets guidelines:– Canadian Environmental Protection Act (transfers of

hazardous materials)– Fisheries Act (illegal to damage water that serves as a

habitat for fish)• The Great Lakes are one success story

– Great Lakes Water Quality Agreement and the International boundary Waters Treaty Act

12-65

We treat our drinking water

• Technology has improved our pollution control• Health Canada publishes standards for drinking water

contaminants– Local governments and water suppliers must meet

• Federal-Provincial-Territorial Committee on Drinking Water

• Before water reaches the user– It is chemically treated, filtered, and disinfected– Sometimes the resulting product can be less than optimal– In some First Nations communities, the water is not even

drinkable; it is of ‘Third World’ standards12-66

• Other options are not as good:– Filtering groundwater expensive– Pumping, treating, and re-injecting aquifers takes too

long– Restricting pollutants above aquifers shifts pollution

elsewhere• Consumers choice drives environmentally friendly

products and decisions

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Waste Water and Its Treatment

12-68

Municipal wastewater treatment involves several steps

• Wastewater = water that has been used by people in some way– Sewage, showers, sinks, manufacturing, storm water

runoff• Septic systems = the most popular method of

wastewater disposal in rural areas– Underground septic tanks separate solids and oils from

wastewater, then microbes decompose the water– Solid waste needs to be periodically pumped and

landfilled

12-69

Municipal wastewater treatment involves several steps (cont’d)

• In populated areas, sewer systems carry wastewater – Physical, chemical, and biological water treatment

• Primary treatment = the physical removal of contaminants in settling tanks (clarifiers)

• Secondary treatment = water is stirred and aerated so aerobic bacteria degrade organic pollutants– Water treated with chlorine is piped into rivers or the

ocean– Some reclaimed water is used for irrigation, lawns, or

industry

12-70

A typical wastewater

treatment facility

12-71

Artificial wetlands can aid treatment• Natural and artificial wetlands can cleanse wastewater

– After primary treatment at a conventional facility, water is pumped into the wetland

– Microbes decompose the remaining pollutants– Cleansed water is released• Nova Scotia government and Nova Scotia Agricultural

College have three test sites• Constructed wetlands serve as havens for wildlife and

areas for human recreation

12-72

Conclusion• One of great challenges is to ensure adequate

quantity and quality of fresh water• With expanding population and increasing water

usage, we are approaching conditions of widespread scarcity

• Water depletion and water pollution are already taking a toll on the health, economics, and societies of the developing world and in arid regions of the developed world

• Potential solutions are numerous, and the issue is too important to ignore

12-73

QUESTION: ReviewThe area of a lake that contains open water that does not receive sunlight is called the _______zone.a) Littoralb) Benthicc) Limneticd) Profundal

12-74

QUESTION: ReviewA confined aquifer is defined as…?

a) An aquifer that traps porous rocks between layers of less

permeable substrateb) An aquifer that traps porous rocks under one layer of less

permeable substratec) An aquifer with porous rocks resting on bedrockd) An aquifer with no upper layer

12-75

QUESTION: ReviewArid countries tend to use their water mostly for…?

a) Developing industriesb) Agriculturec) Householdsd) Export to rich countries

12-76

QUESTION: ReviewWhich of the following statements is not a benefit of dams?

a) Habitat alterationb) Power generationc) Crop irrigationd) Shipping

12-77

QUESTION: ReviewPollution is defined as “the release of matter or energy into the environment that

causes ______”?

a) Undesirable impacts on human healthb) Undesirable impacts on other organismsc) Undesirable impacts on human well-beingd) All of the above are included in the definition

12-78

QUESTION: Review

Which of the following is a nonpoint source of water pollution?

a) A factoryb) Sewer pipesc) Agricultural fieldsd) All are nonpoint sources

12-79

QUESTION: ReviewPrimary treatment of wastewater includes…?

a) Treating water with chemicalsb) Stirring and aerating waterc) Degradation of wastes by bacteriad) Physical removal of contaminants

12-80

QUESTION: Interpreting Graphs and Data

What is the relationship between water consumption and the amount of land that is irrigated?

a) Irrigation has grown more slowly than demand

b) Irrigation and demand have both increased

c) Growth of demand and irrigation will slow

d) Canada does not follow this graph

12-81

FIGURE 11.14

QUESTION: Interpreting Graphs and DataWhich conclusion can you draw from this graph?

a) It is more water efficient to produce vegetables

b) It is more water efficient to produce meat

c) Vegetable and meat production are relatively alike in water consumption

d) There is little correlation between water consumption and our diet

12-82