1 As the global population grows and the demand for water increases, there will be less water per person.
2 For water-rich countries such as Canada or Brazil this decrease is not a serious worry, but elsewhere it can be life-threatening.
3 Globally, half a billion people – most of them
living in Africa and the middle east – are
chronically short of water.
4 There are insufficient renewable supplies of water in China and parts of Europe, while India looks set to suffer considerable water stress in the future.
5 Even in the USA, where water is relatively abundant, availability will have halved between 1955 and 2055, most obviously in the dry southwest.
6 At present, more than one-third of
the world’s population is short of
water, and it is estimated this will
reach 45% by 2025.
7 The United Nations Food and Agriculture Organisation (FAO) expects water demand to
reach 5,235 km3 per year by 2025.
8.1 Agriculture is the major user of water, particularly as we struggle to increase food supplies for a growing global population
8.2 Currently, agriculture uses 69% of the world’s 4,430.7 km3 a year freshwater supply.
8.3 A kilogram of beef, for example, is ten times more ‘water-costly’ to produce than a kilogram of rice.
8.4 Some forms of agriculture are less water-efficient than others.
8.5 At present, 17% of the global area devoted to growing crops is irrigated
8.6 While water storage and irrigation systems do make agriculture more productive, they can also be wasteful of water.
8.7 While water storage and irrigation systems do make agriculture more productive, they can also be wasteful of water.
9.1 The proportion of water used globally by industry (21%) rose relatively slowly during the
twentieth century, mainly in the developed countries of Europe, Russia, Canada and the USA.
9.2 Estimates for the coming decade suggest a more rapid global rise, driven by large-scale industrialisation in countries such as India and China.
9.3 Hydroelectric power (HEP) continues to use huge amounts of water, but this water is available to other users once it has passed through the turbines.
9.4 Industry is generally a much more efficient user of water than agriculture, but there aresome significant
exceptions: paper manufacturing, for example, is one of the most extravagant users of water on the planet.
9.5 Industry has also caused significant
water pollution problems.
10.1 Water usage in homes is the smallest category of consumption, using only 10%.
10.2 The amount used, however, varies
enormously from country to country.
10.3 Most developed countries need at least 100,000 litres of water per person
per year, while in most African countries the figure is less than 50,000 litres.
10.4 Global domestic demand seems to be doubling every 20
years and it is arguably only the poor access in Africa that is
limiting growth in demand there.
10.5 The quality of the water involved also varies considerably.
11 Water Sources
11.1.1 Rivers, lakes and reservoirs provide large amounts of surface water for a wide variety of uses.
11.1.2 So called ‘mega-dams’ are found on most of the world’s major rivers.
11.1.3 Half of all the world’s dams (around 50,000) are in
China, the USA, India and Japan, and their reservoirs
account for a quarter of the global freshwater supply.
11.1.4 The construction of reservoirs brings short-term economic gains in terms
of water supply, hydroelectric power and flood control, but these must be
measured against their longer-term environmental and social impacts.
11.1.5 Large-scale river-water diver- sions
and wetland drainage programmes
also have costs and benefits.
11.2.1 Underground supplies from aquifers are the sole source of drinking water for about a quarter of the world’s population.
11.2.2 Three-quarters of Europe’s drinking water comes from groundwater,
while Bangladesh and India use most of their ground- water for irrigation.
11.2.3 In many countries, for example the
USA, China and India, as well as in
much of the middle east, water is
being abstracted from aquifers faster
than it is being replaced.
11.2.4 The long-term costs of this over-abstraction are dwindling supplies,
falling water tables and seawater contamination.
12 Pressure on water supplies
12.1 In many parts of the world there is a growing mismatch between water
supply and demand. This can be seen locally and across whole regions
12.2 Water stress is the term used when the annual supply of water per
person falls below 1,700 m3. When this figure drops below 1,000 m3,
the term used is water scarcity. There are two types of water scarcity:
12.2.1 Physical Scarcity
126.96.36.199 occurs when more than 75% of a country
or region’s river flows are being used.
188.8.131.52 A quarter of the world’s population lives in such areas, which
include parts of the USA and Australia.
12.2.2 Economic Scarcity
184.108.40.206 Occurs when the development of
blue water flow sources is limited
by human and financial capacities.
220.127.116.11 More than 1 billion people, in areas such as sub-Saharan Africa,
use less than 25% of the river resources available.
13.1 India has 4% of the world’s freshwater, but 16% of its population.
13.2 Demand will probably exceed supply by 2020, as urban water
demand is expected to double and industrial demand to triple.
13.3 Hydrologists calculate that 43% of precipitation never
reaches rivers or aquifers, and water tables are falling
rapidly as 21 million wells abstract water.
14.1 China has 8% of the world’s freshwater but must meet the needs of 22% of the world’s population.
14.2 Two-thirds of Chinese cities do not have enough water all year round,
and national water supplies are likely to reach stress levels by 2030.
14.3 China uses irrigation to produce 70% of its food,
mostly in the north and northeast, where the Yellow
River and major aquifers are running dry.
14.4 Huge engineering projects will
soon transfer vital water to this
area from the water- rich south.
15 The water problems of
the Beijing-Tianjin region
15.1 Beijing, China’s capital, may soon run out of water.
15.2 Each year, the gap between water demand and supply widens, wells dry up,
groundwater and rivers become polluted and ground subsidence worsens.
15.3 Why this is happening
15.3.1 The causes of this deteriorating situation are both physical and human.
15.3.2 Northeast China, where Beijing is located, is prone to floods and, in recent years, droughts.
15.3.3 Most precipitation falls between July and September, sometimes more than half of it within 3 days.
15.3.4 Several wet years can be followed by several dry years.
15.3.5 The capital’s population of 16 million makes it
the second largest city after Shanghai.
15.3.6 On the coast, not far from Beijing, is China’s third largest
city, Tianjin (population 11 million), a major port with
heavy industry, commerce and developing services.
15.3.7 Beijing’s annual population growth rate is stabilising at about 2.5% as a result of efforts by the govern-
ment to restrict family size, but rural–urban migrants continue to arrive. The situation in Tianjin is
15.4 Water Supply
15.4.1 Beijing draws 60% of its water supply from aquifers.
18.104.22.168 These are overexploited, but the water quality is still acceptable.
15.4.2 In the late 1970s and early 1980s, a series of droughts led to increased demands for irri- gation water.
22.214.171.124 This lowered the water table in some areas by as much as
40 m, and some wells were pumped down to the bedrock.
15.4.3 Much of Beijing has
subsided by between
0.5 m and 1 m per year
because of all this
15.4.4 ianjin relies on groundwater for about 30% of its water
supply, but salt water incursion makes the water brackish.
15.4.5 Surface water supply in the region depends on five major rivers which enter the Hai He river system.
15.4.6 Upstream withdrawals and contamination of these rivers have a negative effect on downstream cities, and
Beijing also makes Tianjin’s water problems worse by the scale of its abstractions and pollution.
15.4.7 An aqueduct 2,500 km long has been built, the first phase of a scheme to divert water from the
Three Gorges Dam to the Beijing–Tianjin region.
15.4.8 Projects to improve water quality and conserve water have also been implemented.
15.5 Demand for water
15.5.1 Industrial output in the
region has increased
more than sixfold in the
last 20 years.
15.5.2 Water demand in the Beijing–Tianjin region is currently 4.9 billion m3 per year and continues to rise.
126.96.36.199 Of this, agriculture accounts for about 65%,
although the use of water-saving technologies
means irrigation demands are levelling off.
15.5.3 Water demand has not risen as fast as this as industries have become more water-efficient and recycle their waste water and there has been a shift
from heavy to high-tech industry.
15.5.4 The fastest rate of increase is in domestic water use:
consumption has risen tenfold in the last 50 years and
now aver- ages 240 litres per person per day.