AP Environmental Science Water Resources (Ch 15)

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AP Environmental ScienceWater Resources(Ch 15)

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Waters Unique Properties

• Hydrogen Bonding
• Liquid over wide temperature range
• Changes temperature slowly (High heat capacity,
  Cp)
• High heat of evaporation
• Great dissolving power (nicknamed - Universal
  Solvent)
• Filters out ultraviolet radiation
• Expands when it freezes

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Global Water Distribution

http//ga.water.usgs.gov/edu/waterdistribution.htm
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Hydroglogic Cycle

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Hydroglogic CycleWater storage -Ocean

97 of Global Water 3 salinity Only fresh
water evaporates, salt stays in ocean
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Hydroglogic CycleSurface water/runoff

Surface water - Precipitation that remains on
surface land and does not seep into
soil Runoff - The movement of surface water
across land to rivers, streams and
ultimately to the ocean Watershed or drainage
basin - An area of land where water runs off
into one stream or river.
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Hydroglogic CycleFerndale Wastershed

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Hydroglogic CycleStorage in Glaciers/icecaps

Glacial ice covers 10-11 percent of all
land 68.7 of global freshwater is in
glaciers/icecaps According to the National Snow
and Ice Data Center (NSIDC), if all glaciers
melted today the seas would rise about 230 feet
(70 meters) Largest surface area of any glacier
in the contiguous United States Emmons Glacier,
Washington (4.3 square miles or 11 square
kilometers)
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Hydroglogic CycleGroundwater storage

Water enters aquifers through infiltration in
recharge area

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Hydroglogic Cycle

• What is the general cycle of water on the globe?
• What drives the process?
• What parts of the system provide the ecological
  service of pollution reduction?

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Use of Water Resources

Humans use about 54 of reliable runoff (regular,
predictable runoff, not including
floods) Agriculture - Irrigation Industry -
Cooling, ingredient in product Domestic -
Shower, toilets, lawn watering Power Plants -
Cooling
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Too Little Water

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Too Little WaterStrategies to Counteract

Divert surface water Remove ground water from
confined and unconfined aquifers Build dams and
reservoirs
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Too Little WaterConsequences of Removal of
Surface Water

• Surface water depletion - From diversion of water
  from lakes or rivers
• Rivers can endure 30 diversion
• Some rivers have as much as 70 diverted
• Causes wetlands to dry up
• Disrupts ecosystems

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Too Little WaterConsequences of Removal of
Aquifer Water

• Aquifer Depletion - Excessive removal of
  groundwater lowers the water table
• Can cause
• Subsidence - Sinking of land above aquifer (up to
  10m in CA)
• Sinkhole - More dramatic sinking of land
• Saltwater intrusion - Excessive removal of
  freshwater causes saltwater to contaminate fresh
  ground water

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Too Little WaterSaltwater intrusion

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Too Little WaterTrade-offs of Dams

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Too Little WaterSalinization

Salinization - The increasing build up of
salinity levels due to water diversion and
evaporation Remediation (both very expensive,
energy intensive) Distillation - Heating water
to force evaporation, leaving salt
behind Reverse osmosis - pushing water through
a membrane permeable to water, but not to salt
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Too Much WaterFlooding

Flooding is a natural process and can be
beneficial to humans Ancient Egypt relied on
flooding of rivers to bring nutrient rich river
sediment onto land to increase crop
yield Flooding increased by development
Building in flood plains Removal of trees -
trees naturally trap/store large amounts of
water from precipitation Ontario Canada -
Removal of trees for urbanization caused
annual runoff to increase from 10 to
43 Re-engineering rivers to flow straight -
doesnt dissipate energy of high flows as much
as curvy river
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Too Much Water Flooding

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Using Water Efficiently

• Reduce losses due to leakage
• Reform water laws
• Improve irrigation efficiency
• Improving manufacturing processes
• Water efficient landscaping (xeriscaping)
• Improve efficiencty of appliances

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Using Water EfficientlyXeriscaping

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Irrigation

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Salinization Waterlogging
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Salinization Waterlogging
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Desertification