Global Water Resources January 27, 2014

Properties of Water  Due to Hydrogen Bonding  Stores heat/doesn’t change temperature easily  Dissolves many compounds  Capillary Action  Expands when frozen  Evaporation takes lots of energy  Water filters out harmful UV rays  Exist over a wide temperature range

Availability of Freshwater  Only 0.02% of all water is available as liquid freshwater

Comparison: Population vs. water usage

Per Capita Water Use

Global Water Use

Case Study: Who Should Own and Manage Freshwater Resources  There is controversy over whether water supplies should be owned and managed by governments or by private corporations.

How Would You Vote?  Should private companies own or manage most of the world's water resources?  a. No. Democratically elected governments, which are accountable to the voters, should own and manage water resources.  b. Qualified yes. Governments should own the water, but expert private companies should manage it.  c. Depends. Each case must be decided independently. The record on private versus public ownership is mixed.  d. Yes. Private companies have more expertise and experience in managing water resources than most government bureaucrats.

Surface Water - Watersheds  Watershed: An area of land where all surface runoff goes to the same place (drainage basin)  Determined by landscape (mountains, etc.)  Land Use activities in one part of the watershed will affect other parts of the watershed.

Ground Water  Water table  the level below which the ground is saturated with water.  Aquifer  a body of permeable rock that can hold and/or move groundwater.  Renewable Resource?  unless water is removed faster than it is replenished or if they are contaminated.  Problems  Subsidence  Gradual caving in or sinking of land  can be caused by water mining  Salt-water Intrusion  Pollution Subsidence: San Joaquin Valley

Salt Water Intrusion  Contaminates freshwater wells and groundwater

Groundwater  The Ogallala, the world’s largest aquifer, is most of the red area in the center (Midwest).

Dams & Reservoirs  Large dams and reservoirs can  produce cheap electricity  reduce downstream flooding  provide year-round water for irrigating cropland

Dams, Reservoirs and Aqueducts: Good or Bad? Three Gorges Dam, China Aral Sea, Russia

Case Study: Colorado Basin