Transcript GEOG 101: Day 15

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.
12
Freshwater Systems
and Water Resources
PowerPoint® Slides prepared by Stephen Turnbull
Copyright © 2013 Pearson Canada Inc.
© 2010 Pearson Education Canada
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 largescale 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
12-5
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
12-16
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
12-18
Water is unequally distributed across Earth’s surface
• Many areas with high population density are waterpoor 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
12-20
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
12-22
Water supplies houses, agriculture, and
industry
12-23
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
12-25
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
opportunities
12-27
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.”
12-28
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.
“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.’”
12-29
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 fourthlargest 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
12-32
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
weighing
the issues
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.
12-36
weighing
the issues
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?
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 water
12-40
weighing
the issues
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?
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 environment
12-47
We can lessen residential and industrial
water use in many ways
• 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
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
12-49
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”
12-51
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’ standards
12-66
It is better to prevent pollution than to
mitigate the impacts after it occurs
• 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
12-67
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: Review
The area of a lake that contains open water that does not
receive sunlight is called the _______zone.
a)
b)
c)
d)
Littoral
Benthic
Limnetic
Profundal
12-74
QUESTION: Review
A confined aquifer is defined as…?
a)
b)
c)
d)
An aquifer that traps porous rocks between layers of
less permeable substrate
An aquifer that traps porous rocks under one layer of
less permeable substrate
An aquifer with porous rocks resting on bedrock
An aquifer with no upper layer
12-75
QUESTION: Review
Arid countries tend to use their water mostly for…?
a)
b)
c)
d)
Developing industries
Agriculture
Households
Export to rich countries
12-76
QUESTION: Review
Which of the following statements is not a benefit of dams?
a)
b)
c)
d)
Habitat alteration
Power generation
Crop irrigation
Shipping
12-77
QUESTION: Review
Pollution is defined as “the release of matter or energy into the
environment that causes ______”?
a)
b)
c)
d)
Undesirable impacts on human health
Undesirable impacts on other organisms
Undesirable impacts on human well-being
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)
b)
c)
d)
A factory
Sewer pipes
Agricultural fields
All are nonpoint sources
12-79
QUESTION: Review
Primary treatment of wastewater includes…?
a)
b)
c)
d)
Treating water with chemicals
Stirring and aerating water
Degradation of wastes by bacteria
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
FIGURE 11.14
12-81
QUESTION: Interpreting Graphs and Data
Which 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