Transcript Ch. 14 Water: A Limited Resource Power Point

Chapter 14
Water: A Limited Resource
Overview of Chapter 14
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Importance of Water
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Water Use and Resource Problems
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Sharing Water Resources
Water Management
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Too Much Water
Too Little Water
Water Problems in US and Canada
Global Water Problems
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Hydrologic Cycle
Providing Sustainable Water Supply
Water Conservation
Importance of Water
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Cooking
Washing
Use large amounts
for:
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Agriculture
Manufacturing
Mining
Energy production
Waste disposal
Use of freshwater
is increasing
Properties of Water
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Composed of 2 Hydrogen
and 1 oxygen
Exists as solid, liquid or gas
High heat capacity
Polar
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One end has (+) charge, one
end has (-) charge
Forms Hydrogen bond
between 2 water molecules
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H-bonds define water’s
physical properties
Properties of
Water
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Water is never
completely pure
in nature
Content of
seawater (left)
Many
substances
water dissolves
cause water
pollution
Hydrologic Cycle
Distribution of
Water
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Only 2.5% of water
on earth is
freshwater
2% is in the form
of ice!
Only ~0.5% of
water on earth is
available
freshwater
Freshwater Terminology
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Surface water
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Runoff
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Land area that delivers water into a stream or river
system
Groundwater
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Movement of surface water to lakes, rivers, etc.
Watershed (drainage basin)
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Precipitation that remains on the surface and does not
seep into soil
Freshwater under the earth’s surface stored in
aquifers
Aquifer
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Underground caverns and porous layers of sand, gravel
and rock in which groundwater is stored
Freshwater Aquifer
Water Use and Resource Problems
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Fall into Three Categories
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Too much water
Too little water
Poor quality/contamination (discussed in
Chapter 22)
Too Much Water
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Flooding
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Modern floods are highly destructive
because humans:
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Both natural and human-induced
Remove water-absorbing plant cover from soil
Construct buildings on floodplains
Floodplain
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Area bordering a river channel that has the
potential to flood
Urban vs. Pre-Urban Floodplains
Floodplain
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Government restrictions on building
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Levees can fail
Rather than rebuild
levees adjacent to
rivers, experts
suggest allowing
some flooding of
floodplains during
floods
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(next slide)
Left:
Traditional
levees adjacent
to river
Right:
Suggested levee
style, set back
from river
Case-In-Point Floods of 1993
Too Little Water
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Typically found in arid land
Problems
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Drought
Overdrawing water
for irrigation
purposes
Aquifer depletion
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Subsidence
Sinkholes
Too Little Water
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Problems (continued)
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Saltwater Intrusion
Water
Problems In
US and Canada
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US has a
plentiful supply
of freshwater
Many areas have
a severe
shortages
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Geographical
variations
Seasonal
variations
Water Problems in US and Canada
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Water shortages in West and Southwest
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Water is diverted and transported via aqueducts
Water Problems in US and CanadaSurface Water
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Mono Lake (Eastern CA)
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Rivers and streams that once fed this lake are
diverted to Los Angeles (275mi away)
Becoming highly saline
Court ordered water diversion reduction
Colorado River Basin
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Provides water for 27-million people
Numerous dams for Hydropower
Colorado River no longer reaches ocean
Colorado River bed in Mexico
Water Problems in US and CanadaGroundwater
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Aquifer Depletion
Global Water Problems
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Amount of freshwater on planet CAN meet
human needs
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BUT, it is unevenly distributed and some places
lack stable runoff
Problems:
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Climate Change
Drinking Water
Population Growth
Sharing Water Resources Among Countries
Global Water Problems
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Water and Climate Change
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Climate change affects the type and
distribution of precipitation
Potential issues:
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Reduced snowfall will impact water resources
downstream
Sea level rise will cause saltwater intrusion into
drinking water supplies
Global Water Problems
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Drinking Water Problems
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Many developing countries have insufficient
water to meet drinking and household needs
Population Growth
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Increase in population means an increase in
freshwater requirements
Limits drinking water available
Limits water available for agriculture (food)
Global Water Problems
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Sharing Water Resources
Among Countries
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Rhine River Basin (right)
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Countries upstream discharged
pollutants into river
Countries downstream had to
pay to clean the water before
they could drink it
Aral Sea (next slide)
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Water diversion for irrigation
has caused sea to become too
saline
Aral Sea
1967
1997
Global Water Problems
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Potentially Volatile International Water
Situations
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Jordan River
Nile River
Water Management
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Main Goal: Provide sustainable supply of
high-quality water
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Requires humans to use resource carefully
Dams and Reservoirs
Water Diversion Projects
Desalinization
Dams and Reservoirs
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Benefits:
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Ensure year-round supply
of water with regulated
flow
Generate electricity
Provide recreational
activities
Disadvantages
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Alter the ecosystem
Reduce sediment load
Dams and Reservoirs
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Glen Canyon Dam
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Regulated flow has changed ecosystem
To rectify situation
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Canyon has been flooded several times
Small floods compared to natural floods
Still helps rebuild habitat
Dams and Reservoirs
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Salmon Population in
Columbia R. very low
due to dams that
impede migration
Fish ladders help,
but are not
effective enough
Water Diversion Projects
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Requires diverting
water to areas that
are deficient by
pumping through a
system of aqueducts
Much of CA’s receives
its water supply from
diverted water from
Northern CA
Controversial and
expensive
Desalinization
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Removal of salt from ocean or brackish
water
Two methods:
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Distillation- salt water is evaporated, and
water vapor is condensed into freshwater (salt
left behind)
Reverse Osmosis- involves forcing salt water
through a membrane permeable to water, but
not salt
Very expensive
Water Conservation
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Reducing Agricultural Water Waste
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Agriculture is very inefficient with water
Microirrigation- irrigation that conserves
waster by piping to
crops through sealed
systems
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Also called drip or
trickle irrigation
Water Conservation
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Reducing Industrial Water Waste
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Stricter laws provide incentive to conserve
water
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Recycling water within the plant
Water scarcity (in addition to stricter
pollution control requirements) will encourage
further industrial recycling
Potential to conserve water is huge!
Water Conservation
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Reducing Municipal
Water Waste
Gray Water
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Can be used to flush
toilets, wash car or
water lawn
Water saving
household fixtures
Government
incentives
Conserving at Home
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Install water-saving shower heads and
faucets
Install low-flush toilets
Fix leaky fixtures
Purchase high efficiency appliances
Modify personal habits
Use the dishwasher instead of washing by
hand