Page 278 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

242 part II The Water, Weather, and Climate Systems
decrease in the southern prairie region. This will lead to greater aridity, reduced soil moisture, and greater pressure on limited groundwater supplies, particu- larly in summer.
it is clear that with climate change, diminishing water resources, and increas- ing population, human activity and water use policies in the southern prairie prov- inces must adapt.
Earth’s physical processes are dependent on water, which is the essence of all life. Humans are about 70% water, as are plants and other animals. We use water to cook, bathe, wash clothes, dilute wastes, and run industrial processes. We use water to produce food, from the scale of small gardens to vast agricultural tracts. Water is the most critical resource supplied by Earth systems.
In the Solar System, water occurs in significant quantities only on our planet, covering 71% of Earth by area. Yet water is not always naturally available where and when we want it. Consequently, we rearrange water resources to suit our needs. We drill wells to tap ground- water and dam and divert streams to redirect surface water, either spatially (geographically, from one area to another) or temporally (over time, from one part of the calendar to another). All of this activity constitutes water- resource management.
Fortunately, water is a renewable resource, con- stantly cycling through the environment in the hydro- logic cycle. Even so, some 1.1 billion people lack safe drinking water. People in 80 countries face impending water shortages, either in quantity or in quality, or both. Approximately 2.4 billion people lack adequate sanitary facilities—80% of these in Africa and 13% in Asia. This translates to some 2 million deaths a year due to lack of water and 5 million deaths a year from waterborne in- fections and disease. Investment in safe drinking water, sanitation, and hygiene could decrease these numbers. During the first half of this century, water availability per person will drop by 74% as population increases and adequate water decreases.
A 2011 report from the World Water Assessment Program of UNESCO (www.unesco.org/water/wwap/) states,
As water demand and availability become more uncertain, all societies become more vulnerable to a wide range of
geosystems now online go to Chapter 9 on the MasteringGeography website (www .masteringgeography.com) for more in- formation about the effects of changing climate.
risks associated with inadequate water supply, including hunger and thirst, high rates of disease and death, lost pro- ductivity and economic crises, and degraded ecosystems. These impacts elevate water to a crisis of global concern . . . [A]ll water users are—for better or worse and knowingly or unknowingly—agents of change who affect and are affected by, and connected through, the water cycle.
In this chapter: We begin with the origin and dis- tribution of water on Earth. We then examine the hydro- logic cycle, which gives us a model for understanding the global water balance. Next we introduce a water- budget approach to look at water resources. Similar in many ways to a money budget, it focuses attention on water “receipts” and “expenses” at specific locations. This budget approach can be applied at any scale, from a small garden to a farm to a regional landscape such as Palliser’s Triangle, discussed in Geosystems Now.
Also we examine the various types of surface and groundwater resources, and discuss issues concern- ing water quantity and quality on a national and global basis. The chapter concludes by considering the quan- tity and quality of the water we withdraw and consume for irrigation, and industrial and municipal uses. For many parts of the world, the question of water quantity and quality looms as the most important resource issue in this century.
Water on Earth
Earth’s hydrosphere contains about 1.36 billion cubic ki- lometres of water (more specifically, 1359208000 km3). Much of Earth’s water originated from icy comets and from hydrogen- and oxygen-laden debris within the planetesimals that coalesced to form the planet. In 2007, the orbiting Spitzer Space Telescope observed for the
greater emphasis on water conser- vation and more efficient use of water is needed. However, even with such measures, activities in areas with mar- ginal water supplies may have to shift location, or cease. For example, land cur- rently on the edge of the viable farming region may transition into less-intensive ranch land. Clearly, water resource issues in this region need our attention.
Georeport 9.1 The Water We Use
On an individual level, Canadians use an average of 326 litres of water per person per day, but this figure varies widely by location. The daily domestic use in litres per person per day varies from 156 litres in Charlottetown to 470 litres in Hamilton,
Ontario. Take a moment and speculate why there is a difference (compare rural vs. urban populations). However, overall individual water use is actually much higher than these figures because of indirect use, such as consuming food and beverages made using water-intensive practices. See www.worldwater.org/data.html, World’s Water 2008–2009, Table 19, for more on these indirect uses of water. Canadian examples are documented by the Sustainable Water Project at poliswaterproject.org/publication/27.