Water%20Resources

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Chapter 13

• Water Resources

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Supply of Water Resources
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Core Case Study Water Conflicts in the Middle
East - A Preview of the Future

• Many countries in the Middle East, which has one
  of the worlds highest population growth rates,
  face water shortages.

Figure 14-1
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Water Conflicts in the Middle East A Preview of
the Future

• Countries are in disagreement as to who has water
  rights.
• Currently, there are no cooperative agreements
  for use of 158 of the worlds 263 water basins
  that are shared by two or more countries.

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Soil Properties

• Infiltration

• Porosity/permeability

• Texture
• Soil type here?

Clay, granite
Sand, gravel
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Zone of aeration Zone of saturation
Groundwater
Unconfined Aquifer Recharge Area
Evaporation and transpiration
Evaporation
Precipitation
Confined Recharge Area
Runoff
Flowing artesian well
Recharge Unconfined Aquifer
Stream Well requiring a pump
Water table
Infiltration
Lake
Infiltration
Unconfined aquifer
Less permeable material such as clay
Confined aquifer
Confining impermeable rock layer
Fig. 13-3,
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Tapping Groundwater

• Year-round use

• No evaporation losses

• Often less expensive

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Other Effects of Groundwater Overpumping- Sea
water intrusion

• Groundwater overpumping can cause land to sink,
  and contaminate freshwater aquifers near coastal
  areas with saltwater.

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Other Effects of Groundwater Overpumping-subsidenc
e

• Sinkholes
• Chemical contamination.

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Use of Water Resources
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Case Study The California Experience

• A massive transfer of water from water-rich
  northern California to water-poor southern
  California is controversial.
• Water rights
• Prior appropriation
• riparian

Figure 13-17
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Converting Salt Water to Fresh Water and Making
it Rain

• Distillation desalination

• Reverse osmosis desalination

• Desalination is very expensive

• Cloud seeding

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Provides water for year-round irrigation of
cropland
Flooded land destroys forests or cropland and
displaces people
Large losses of water through evaporation
Provides water for drinking
Downstream cropland and estuaries are deprived of
nutrient-rich silt
Reservoir is useful for recreation and fishing
Risk of failure and devastating downstream
flooding
Can produce cheap electricity (hydropower)
Downstream flooding is reduced
Migration and spawning of some fish are disrupted
Fig. 13-12
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Case Study Chinas Three Gorges Dam

• There is a debate
• The electric output
• It will facilitate ship travel reducing
  transportation costs.
• Dam will displace 1.2 million people.
• Dam is built over seismatic fault and already has
  small cracks.

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Dam Removal

• Some dams are being removed for ecological
  reasons and because they have outlived their
  usefulness.
• The Federal Energy Regulatory Commission has
  approved the removal of nearly 500 dams.
• Removing dams can reestablish ecosystems, but can
  also re-release toxicants into the environment.

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Using Water More Efficiently

• Reduce losses due to leakage

• Reform water laws

• Improve irrigation efficiency

• Improving manufacturing processes

• Water efficient landscaping

• Water efficient appliances

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INCREASING WATER SUPPLIES BY WASTING LESS WATER

• Sixty percent of the worlds irrigation water
• Center-pivot, low pressure sprinklers sprays
  water directly onto crop.
• It allows 80 of water to reach crop.

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Drip irrigation
(efficiency 9095)
Gravity flow
(efficiency 60 and 80 with surge valves)
Center pivot
(efficiency 8095)
Water usually pumped from underground and sprayed
from mobile boom with sprinklers.
Above- or below-ground pipes or tubes deliver
water to individual plant roots.
Water usually comes from an aqueduct system or a
nearby river.
Fig. 13-20
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Solutions Getting More Water for Irrigation in
Developing Countries The Low-Tech Approach

• low-tech methods to pump groundwater
• Arsenic in India

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Raising the Price of Water A Key to Water
Conservation

• We can reduce water use and waste by raising the
  price of water while providing low lifeline rates
  for the poor.
• When Boulder, Colorado introduced water meters,
  water use per person dropped by 40.

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What Can You Do?
Water Use and Waste
Use water-saving toilets, showerheads, and
faucet aerators.
Shower instead of taking baths, and take short
showers.
Stop water leaks.
Turn off sink faucets while brushing teeth,
shaving, or washing.
Flush toilets only when necessary.
Wash only full loads of clothes or use the
lowest water-level for smaller loads.
Use recycled (gray) water for lawn, gardens,
house plants, car washing.
Wash a car from a bucket of soapy water, and
use the hose for rinsing only.
If you use a commercial car wash, try to find
one that recycles its water.
Replace your lawn with native plants that need
little if any watering and decorative gravel or
rocks.
Water lawns and gardens in the early morning or
evening.
Sweep or blow off driveways instead of hosing
off with water.
Use drip irrigation and mulch for gardens and
flowerbeds.
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Too Much Water Floods

• Natural phenomena

• Aggravated by human activities

• Renew and replenish

Flood zone
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TOO MUCH WATER

• Comparison of St. Louis, Missouri under normal
  conditions (1988) and after severe flooding
  (1993).

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Water Conservation

• The average American uses 90 gallons of water
  each day. European-53 and Sub-Saharan Africa-5
• Fix leaks, replace old toilets (trade ins),
  efficient washers (50 less water and energy).
• A switch to water efficient appliances family of
  4- save 23,000 gallons a year.
• End chapter 13