The Hydrological Cycle

The Hydrological Cycle (better art)

Where is the Water

Active Pools:

• Atmosphere: 720,000
• Soil Moisture 3,700,000
• Stream Channels 69,000
• Fresh Water Lakes 6,900,000
• Saline Lakes/Inland Seas 5,800,000
• Oceans 74,000,000,000

Storage Pools:

• Ice Caps and Glaciers 1,600,000,000
• Groundwater 460,000,000

Groundwater is a major untapped source of fresh water but everyday more toxins seep into it. Note that there is approximately 5000 times more water stored as groundwater than is in surface streams

Components of the Hydrological Cycle

Dam building seriously alters the hydrological cycle.

This is especially true in the American Southwest

What happened to the Colorado River

• Originally it reached northern mexico and fed a thriving agrarian economy in the early 20th century
• Source is in Rocky Mountains of Colorado
• San Juan mountains in SW colorado have a large snowpack, which feeds the river
• In 1922 the water rights to the river were allocated to California, Arizona, Nevada, Utah and Colorado
• Allocation was based on river flow during the period 1900-1920 which turns out to have been anamolously high --> therefore the river was overallocated
• Depression hits so Hoover dam is built as part of the effort to reclaim the West (see also the excellent Cadillac Desert Series
• Water backs up into reservoir and increases surface area to evaporation
• Reservoir lined with porous sandstone so water loss due to seepage into sandstone occurs
• Lake Havasu was created for London Bridge --> additional recreational dams were built (e.g. Parker Dam
• As more and more of the Colorado became prown to evaporation its salinty increased
• Eventually the water that reached Mexico was too saline for agriculture. Mexican government sued and won. US built a nuclear powered desalination plant in Yuma Arizona
• Now no water gets there ... unless we really pour it on

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