Water
EB
Lecture 11
2008 Spring
Agenda
•
•
•
•
•
•
•
Understand freshwater systems
Use of water
Depletion of water
Water Pollution
Marine water
Ocean Impact
Marine Conservation
Case Study 1
Aral Sea
Aral Sea
•
•
•
•
Location: Asia
Type: Freshwater
Issue: Overuse
What was the
fourth biggest
inland sea is now
mostly desert
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Too much use
• Soviet Union diverted two rivers which
fed the Aral Sea
• to grow cotton in the desert
• However, they created an ecological and
human disaster
– Disease and cancer are rife in the
population.
– 60,000 fishing jobs are gone
– Cotton fields are down
– The fresh water is contaminated with salt
Case Study 2
Colorado River
Colorado River
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Nevade
• Southern Nevada gets nearly 90
percent of its water supply from the
Colorado River.
• The river begins as snowmelt in the
Rocky Mountains.
• The snowmelt travels through a series
of tributaries into the river, which winds
its way south for 1,400 miles and
empties into the Gulf of California
Seven States
• The Colorado River is one of the most
controlled and litigated rivers in the
world.
• Seven western states and Mexico share
the water, which serves about 25 million
people
• The river is divided among Arizona,
California, Colorado, Nevada, New
Mexico, Utah and Wyoming according to
a 1922 Colorado River Compact.
Where is my water?
• Most times not a single drop empties
into the Gulf of Mexico.
• Every drop is used now.
• What of the future?
• Disputes have already started.
• What alternatives exist?
Freshwater Systems
Two types of water
• Fresh water - low in minerals
• Sea water - high in salt and other
minerals
• How much of each type is there on
Earth?
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Hydrologic Cycle
• Water circulates between the different
sources
• Constantly moving physical and organic
elements
• Key to life
Rivers and Streams
• These begin life from
– Rainfall
– Snowmelt
– Springs
• Tributaries flow into each other and then
rivers, then to either lakes or oceans
• Key in spreading silt - vital for organic life
• Floodplains also receive silt.
Lakes and Ponds
• Bodies of standing water
• Demarcation to;
– Littoral zone - where plant life grows to
emerge from water
– Benthic zone - bottom surface
– Limnetic zone - where light penetrates
– Profundal zone - no light - it is dark!
Marshes, Swamps, Bogs
• Mix of dryland and freshwater = wetlands
• Marsh
– Shallow water covering
• Swamp
– As marsh but with forests
• Bog
– Water covered with thick vegetative mats
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Wetlands
• Extremely important
– Buffers
– Pollution controls
– Over 50% of US wetlands are gone!
– Most made into farmland, or
– developments
Groundwater
• Water not sequestered elsewhere will
percolate into the ground to form
groundwater
• Aquifers - porous rocks containing water
• Water table - boundary between water
saturated rock and layer above.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
•
•
•
•
•
•
Groundwater
Fresh water
Slow to form
Most aged at 1,400 years
Large deposits
Ogallala Aquifer - largest in the world
Reduced by 10%
Water distribution is
uneven
•
•
•
•
Different regions have differing rainfall
Differing groundwater
Differing surface water
Some regions have more water than
other per head
– Most in Hawaii
– Least in Chile
Water Usage
We depend on water
• 70% for agriculture
• 20% for industry
• 10% for residential and municipal use
• Consumptive use - not returned
• Non-consumptive use - returned
I’ll be DAMMED
• Humans have erected dams on nearly
every water way in the world.
• Why?
– Drinking water
– Irrigation
– Hydroelectric energy
– Colorado River extensively dammed.
Water ‘mining’
• Extraction of water faster than
replacement is leading to problems
– Subsidence
– Falling water tables
– Salt water intrusion
– Drying wetlands
Water Wars
• As water becomes limiting there will
likely be conflict
• Middle East - started
• Even current treaties such as India and
Pakistan will be faces with strains as the
demand for clean fresh water increases
Water woes
• One can
• Ship it in - from other places
• Make it - from sea water - desalination
– Expensive and energy intensive
• Reverse osmosis
• Filtration
• Distillation
Solutions
• Reduce demand
– Better irrigation - drip irrigation
– Match plants to region
– Genetically improve plants
– Reduce amount of meat eaten!
• Increase supply
– From where?
Water Pollution
Water Quality
• Amount is one aspect
• The other is quality
• Polluted water has a cost
– Disease
– Poisonous
Point source pollution
• Point source pollution comes from a single
defined source - factors
• Non-point source pollution comes from
multiple sources
–
–
–
–
–
Farm runoff
Fertilizer use
Winter salting
Oil leaks
Animal waste
Eutrophication
•
•
•
•
•
•
Fresh water can suffer from this too
Phosphorus causes issues of overgrowth
Hypoxia results from bacterial activity
Biological pollution is the major issue
Contaminated water - from sewage
Spinach anyone???????
Toxic outcomes
•
•
•
•
•
•
Heavy metals in water
Acid rain
Water erosion
Sediment release
Temperature pollution
Water treatment facilities
Marine Systems
• Complex interactions exist.
Human Impact
On the Oceans
•
•
•
•
•
Nets
Plastics
Oil
Nutrients
Red tides
Overfishing
• On the brink
• Over fishing
– Smaller fish
– Younger fish
• Non-target kills
• Market driven fisheries management
Help is coming
•
•
•
•
•
From the UN
From each country
From the community
MPAs
Marine Reserves
– Data suggests that they may work!!!