Page 304 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

268 part II The Water, Weather, and Climate Systems
World annual water withdrawals 3414 km3
11%
80%
20%
69%
14%
41%
Europe
9% 7%
Asia
Canada 45 U.S. 448
9%
Europe 476 Asia 2007
8%
45%
65%
27% Canada 11%
6% 9%
85%
84% 13% 30%
Oceania 57%
United States
Africa 149 Oceania 24
South America 141
Domestic Agriculture Industry
South America
Africa
1500 3000 KILOMETRES
[values in km3]
0
▲Figure 9.19 Water withdrawal by sector. World annual water withdrawal estimated total is 3414 km3. Compare industrial water use among the geographic areas, as well as agricultural and municipal uses. [after World resources institute. World resources 2000–2001, Data Table FW.1, pp. 276–77.]
CRiTiCALthinking 9.3 That Next Glass of Water
you have no doubt had several glasses of water so far today. Where did this water originate? Obtain the name of the water company or agency, determine whether it is using surface or groundwater to meet demands, and check how the water is metered and billed. if your prov- ince requires water-quality reporting, obtain a copy from the water supplier of an analysis of your tap water. read this report, for you always want to know about that “next glass of water.”•
Future Considerations
When water supply and demand are examined in terms of water budgets, the limits of water resources become ap- parent. In the water-budget equation in Figure 9.10, any change in one side (such as increased demand for surplus water) must be balanced by an adjustment in the other side (such as an increase in precipitation). How can we satisfy the growing demand for water? Water availability per person declines as population increases, and individ- ual demand increases with economic development, af- fluence, and technology. World population growth since
1970 reduced per capita water supplies by a third. In ad- dition, pollution limits the water-resource base, so that even before quantity constraints are felt, quality prob- lems may limit the health and growth of a region.
Since surface and groundwater resources do not respect political boundaries, nations must share water resources, a situation that inevitably creates problems. For example, 145 countries of the world share a river basin with at least one other country. Streamflow truly repre- sents a global commons.
The Human Denominator 9 lists some of the interac- tions between humans and water resources, and some of the water-related issues for the century that lies ahead. One of the greatest challenges for humans will be the projected water shortages connected with global warm- ing and climate change. Water is going to be the major source of international conflict in this century.
Clearly, international cooperation is needed, yet we continue toward a water crisis without a concept of a world water economy as a frame of reference. One of the most important questions is: When will more inter- national coordination begin, and which country or group of countries will lead the way to sustain future water resources? The water-budget approach detailed in this chapter is a place to start.
20%
9%
World 71%
Georeport 9.5 Metering Personal Water Use in Canada
Canadians are second only to the United States as the highest per capita users of water in the world. Water use for mu- nicipal supply stresses surface reservoirs and groundwater aquifers. Treating and distributing water uses energy and has a
heavy economic cost. after use, the released water is usually poorer in quality, diminishing the condition of the downstream supply. The direct costs of supplying water are often unnoticed by the average user. in a 1999 national water survey, unmetered house- holds used 433 litres of water per person per day. in metered households where water was paid for by the volume used, the daily residential water use was 288 litres per person per day. Water meters are clearly an effective conservation mechanism, saving the consumer money on water bills and future outlays for more water-supply infrastructure.