Freshwater Resources

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Freshwater Resources
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Water

• Importance of water for human, animals, plants
• Humans, and other organisms, are mostly water.
• Water
• 60 body weight in male
• 55 body weight in female.
• Intracellular water
• cytoplasm water, proteins, salts
• Intercellular fluid
• Blood plasma, cerebrospinal fluid, etc.

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Exchanges of water

• Intake
• Ingestion
• food, drinks
• Loss
• Urination
• Defecation
• Perspiration
• Minor losses
• bleeding, menstruation, lactation, etc.

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Physical Chemical properties of water

• Hydrogen bonding,
• forces of attraction between molecules account
  for other properties

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Physical Chemical properties of water

• Liquid over wide temperature range
• which happens to correspond to temps on Earth
• High specific heat, changes temperature slowly
• Holds carries much heat energy in large water
  bodies
• High heat of vaporization,
• Heat recovered when water condenses, heat of
  condensation
• Solvent
• Dissolves wide variety of substances
• Expands when freezes (ice floats!)

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Where is the water?

• Earth is the water planet
• Blue as seen from space.
• 70 of surface is water

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Where is the water?

• Earth is the water planet
• 70 of surface is water
• 97 by volume is salt water
• undrinkable, not usable by most plants
• 3 freshwater

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Distribution of fresh water

• Surface water
• lakes, streams, rivers, wetlands
• Watershed, drainage basin

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Distribution of fresh water

• Groundwater
• Water that has infiltrated through soil into
  deeper, porous sediments rock in sand,
  sandstone, volcanic ash layers
• usually below water table
• Recharge area

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Freshwater Resources

• Water is unequally distributed
• per capita availability

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Use of fresh water

• Agriculture
• worldwide 70 of surface water used on 17 of
  cropland.
• 60-80 evaporates or seeps below roots, wasted

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Use of fresh water

• Industry 20
• Solvent, Cleaner, Coolant
• Essential part of product

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Use of fresh water

• Domestic/Residential civic use 10
• Drinking and food preparation
• Fountains, pools, lawns, parks, golf courses
• Flushing sewage

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Freshwater Resources

• In USA
• Distribution of population
• Distribution of freshwater

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Fresh water shortage

• Causes
• Dry climate
• Drought
• time period of rainfall deficit and/or high
  evaporation
• Desiccation
• loss of soil moisture because of deforestation,
  overgrazing, etc. May cause higher evaporation
  failure of recharge.
• Water stress
• low per capita availability. Too many people/
  water

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Fresh water shortage

• Causes
• Dry climate
• Drought
• Desiccation
• Water stress

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Fresh water shortage

• Depletion of surface water
• Aral Sea

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Fresh water shortage

• Depletion of surface water
• Colorado River

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Fresh water shortage

• Depletion of ground water
• Ogallala Aquifer
• Worlds largest

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Fresh water shortage

• Depletion of surface water
• Colorado River

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Increasing water supply

• Build dams, reservoirs
• Bring water from elsewhere
• pipes, aqueducts
• Withdraw groundwater
• Desalination
• Improve efficiency (stop waste)

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Increasing water supply

• Build dams, reservoirs (Buford Dam, Lake Lanier)
  
• Benefits
• Hydroelectric power
• Irrigation
• Control flooding
• Source of water for cities, industry etc.

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Increasing water supply

• Build dams, reservoirs
• Drawbacks
• reduce downstream flow,
• habitat loss in river estuary
• flood valleys upstream,
• farmland, forests, people displaced
• weight of dam reservoir alters geology,
• ? earthquakes
• siltation fills reservoir
• dam failure ? catastrophic flood
• Johnstown Flood, PA. 31 May 1889)

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Increasing water supply

• Bring water from elsewhere
• Benefits
• irrigation
• source for cities, industry
• Drawbacks
• Costs of pipelines, pumps, etc.
• Habitat loss
• Depletion of another resource
• Mono Lake, CA
• Aral Sea