apes chapter 14 water resources. water’s unique properties hydrogenbonding hydrogen bonding ...
TRANSCRIPT
APES Chapter 14
Water Resources
Water’s Unique Properties Hydrogen bonding Liquid over wide temperature range Changes temperature slowly High heat of evaporation
Great dissolving power Helps regulate pH Adhesion and cohesion
Expands when it freezes Expands when it freezes
ALL Because it’s POLAR
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Supply of Water Resources
Fig. 14-2 p. 314Fig. 14-2 p. 314
FreshwaterFreshwater Readily accessible freshwaterReadily accessible freshwater
Biota0.0001%
Biota0.0001%
Rivers0.0001%Rivers
0.0001%
Atmosphericwater vapor
0.0001%
Atmosphericwater vapor
0.0001%
Lakes0.0007%
Soilmoisture0.0005%
Groundwater0.592%
Groundwater0.592%
Ice capsand glaciers
1.984%
0.014%0.014%
What is Surface Water?
• Precipitation that does not infiltrate the ground or return to the atmosphere by evaporation.– Example: A watershed (drainage basin) is a
region from which water drains into a stream, lake, reservoir, wetland, or other body of water.
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What is Groundwater?
• Precipitation that infiltrates into the ground and percolates downward through spaces between soil and rock.– Near the surface, these voids contain little
moisture.– Deeper, in the zone of saturation, the voids
are completely filled with water.
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• The water table is located at the top of the zone of saturation.
• Porous, water-saturated layers of sand, gravel , or rock are called aquifers.
• An area of land through which water passed downward into an aquifer is the recharge area.
• If water is withdrawn from an aquifer faster than it can recharge the aquifer will become depleted.
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Ground Water
Evaporation and transpiration
Evaporation
Stream
Infiltration
Water tableInfiltration
Unconfined aquifer
Confined aquifer
Lake
Well requiring a pump
Flowingartesian well
Runoff
Precipitation
ConfinedRecharge Area
Aquifer
Less permeable materialsuch as clay Confirming permeable rock layer
Fig. 14-3 p. 315Fig. 14-3 p. 315
Use of Water Resources
Humans use about 50% of reliable runoff
Agriculture
Industry
Domestic
Power plants
Fig. 14-5 p. 316Fig. 14-5 p. 316
United States
Industry 11%
Public 10%
Powercooling
38%
Agriculture38%
What causes freshwater shortages?
Dry climate
Drought
Desiccation
Water stress
Acute shortage
Adequate supply
Shortage
Metropolitan regions with population greater than 1 millionFig. 14-7 p. 317Fig. 14-7 p. 317
How can we increase Freshwater Supplies?
• Build dams and reservoirs• Bring in water from another area• Withdraw groundwater• Waste less water• Import food to reduce water use
Building Dams
Advantages• Control flooding• Produce hydroelectric
power• Supply water for towns
and cities• Provide recreational
activities such as fishing and boating
Disadvantages• Large water loss through
evaporation• Land lost • Migration and spawning
of some fish disrupted• No nutrient-rich silt
downstream of dam
Using Dams and Reservoirs to Supply More Water
Large lossesof water throughevaporation
Large lossesof water throughevaporation
Flooded land destroys forests or cropland anddisplaces people
Flooded land destroys forests or cropland anddisplaces people
Downstream flooding is reducedDownstream flooding is reduced
Downstream cropland andestuaries are deprived ofnutrient-rich silt
Downstream cropland andestuaries are deprived ofnutrient-rich silt
Reservoir is useful for recreation and fishing
Can produce cheap electricity (hydropower)
Migration and spawning of some fish are disruptedMigration and spawning of some fish are disrupted
Provides waterfor year-roundirrigation ofcropland
Fig. 14-9 p. 319Fig. 14-9 p. 319
Transferring water form another area
Advantages• Supplies water for
agricultural, domestic, and industrial needs
Disadvantages• Degrade rivers• Deplete groundwater• Threaten fisheries
Tapping Groundwater
Advantages• Year round supply• Not lost by evaporation• Less expensive to
develop than surface water sources
Disadvantages• Water table lowering• Aquifer depletion• Intrusion of salt water into
aquifers• Reduce stream flow• May be contaminated by
septic tanks or industrial activities
Desalination
Advantages• Can provide fresh water
from very abundant salt water
Disadvantages• Very expensive• Produces large quantities
of wastewater
How Can We Use Water More Efficiently?
Reduce losses due to leakage
Reform water laws
Improve irrigation efficiency (Fig. 14-18 p. 330)
Improving manufacturing processes
Water efficient landscaping
Water efficient appliances
Too Much Water: Floods
Natural phenomena
Floodplain
Levee Floodwall
Dam
Reservoir
Renew and replenish
Aggravated by human activities
Fig. 14-22 p. 332
Solutions: Achieving a More Sustainable Water Future
Efficient irrigation
Water-saving technologies
Improving water management
See Fig. 14-25 p. 336See Fig. 14-25 p. 336