Page 305 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

THEhumanDENOMINATOR 9 Water Use
WATER RESOURCES HUMANS
• Freshwater, stored in lakes, rivers, and groundwater, is a critical resource for human society and life on Earth.
• Drought results in water deficits, decreasing regional water supplies and causing declines in agriculture.
HUMANS WATER RESOURCES
• Climate change affects lake thermal structure, and associated organisms. • Water projects (dams and diversions) redistribute water over space and time.
• Groundwater overuse and pollution deplete and degrade the resource, with side effects such as collapsed aquifers and saltwater contamination.
9a
Desalination is an important supplement to water supplies in regions with large variations in rainfall throughout the year and declining groundwater reserves. This plant in Andalucía, Spain, uses the process of reverse osmosis to remove salts and impurities. [Jerónimo Alba/Alamy.]
9b
The third largest reservoir in the world, Lake Nasser is impounded by the Aswan High Dam on the Nile River in Egypt. Its water is used for agricultural, industrial, and domestic purposes, as well as for hydropower. [WitR/Shutterstock.]
9c
160 150
140 130 120
September
7, 2006
September 15, 2009
9d
The Itaipu Dam and power plant on the Paraná River bordering Brazil and Paraguay produces more electricity annually than the Three Gorges Dam in China. Itaipu Reservoir displaced over 10 000 people and submerged Guaira Falls, formerly the world’s largest waterfall by volume. [Mike Goldwater/Alamy.]
2003
2004
2005
Quadishaya Reservoir
Euphrates River
2006 2007
Year
0 5 10 KILOMETRES
2008 2009
Quadishaya Reservoir
Euphrates River
ISSUES FOR THE 21ST CENTURY
Data from GRACE reveal a rapid decline in reservoir levels from 2003 to 2009 along the Euphrates River in the Middle East; Quadishaya Reservoir is an example. The graph shows the surface-level decline, with dates of the images marked. About 60% of the volume loss is attributed to groundwater withdrawals in the region. [Image: Landsat-5, NASA. Graph based on data from UC Center for Hydrologic Monitoring.]
• Maintaining adequate water quantity and quality will be a major issue. Desalination will increase to augment freshwater supplies.
• Hydropower is a renewable energy resource; however, drought-related streamflow declines and drops in reservoir storage interfere with production. • Drought in some regions will intensify, with related pressure on groundwater and surface water supplies.
• In the next 50 years, water availability per person will drop as population increases, and continuing economic development will increase water demand.
0 5
10 KILOMETRES
[NASA.]
geosystemsconnection
in this chapter, we looked at water resources through a water-budget approach. Such a systems view, considering both water supply and water demand, is the best method to understand the water resource. The ongoing drought in the western United States brings the need for such a water-budget strategy to the forefront. Water resources being the ultimate output of the water– weather system, we now shift our attention to climate. in Chapter 10, we examine world climates and in Chapter 11, we discuss natural and human-caused climate change.
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Reservoir level (m)