10.4: Water Use and Distribution
- Page ID
- 28283
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In the United States, 355 billion gallons of ground and surface water are withdrawn for use each day, of which 76 billion gallons are fresh groundwater. The state of California accounts for 16% of national groundwater withdrawals [8].
Surface Water Distribution
Surface water makes up only 1.2% of the freshwater available on the planet, and 69% of that surface water is trapped in ground ice and permafrost. Water in rivers accounts for only 0.006% of all freshwater and lakes contain only 0.26% of the world’s freshwater [9]. Freshwater is a precious resource and should not be taken for granted, especially in dry climate areas.
Global circulation patterns are the most important factor in precipitation, and thus, the distribution of surface water. For reasons discussed in the chapter on Deserts, some areas receive a lot of precipitation, and others very little.
In the United States, the 100th Meridian roughly marks the boundary between the humid and arid parts of the country while west of the 100th Meridian, irrigation is required to grow crops [13]. In the West, surface water is stored in reservoirs and mountain snowpacks [14], then strategically released through a system of canals during times of high use.
Groundwater Distribution
| Water source | Water volume
(cubic miles) |
Freshwater (%) | Total water (%) |
|---|---|---|---|
| Oceans, Seas, & Bays | 321,000,000 | — | 96.5 |
| Ice caps, Glaciers, & Permanent Snow | 5,773,000 | 68.7 | 1.74 |
| Groundwater | 5,614,000 | — | 1.69 |
| — Fresh | 2,526,000 | 30.1 | 0.76 |
| — Saline | 3,088,000 | — | 0.93 |
| Soil Moisture | 3,959 | 0.05 | 0.001 |
| Ground Ice & Permafrost | 71,970 | 0.86 | 0.022 |
| Lakes | 42,320 | — | 0.013 |
| — Fresh | 21,830 | 0.26 | 0.007 |
| — Saline | 20,490 | — | 0.006 |
| Atmosphere | 3,095 | 0.04 | 0.001 |
| Swamp Water | 2,752 | 0.03 | 0.0008 |
| Rivers | 509 | 0.006 | 0.0002 |
| Biological Water | 269 | 0.003 | 0.0001 |
| Source: Igor Shiklomanov’s chapter “World freshwater resources” in Peter H. Gleick (editor), 1993, Water in Crisis: A Guide to the World’s Fresh Water Resources (Oxford University Press, New York) | |||
Groundwater makes up 30.1% of the freshwater on the planet, making it the most abundant reservoir of freshwater accessible to most humans. The majority of freshwater, 68.7%, is stored in glaciers and ice caps as ice [9]. As the glaciers and ice caps melt due to global warming, this freshwater is lost as it flows into the oceans.