Washington, D.C.---Some
1.2 billion people-almost a fifth of the world-live in areas of
physical water scarcity, while another 1.6 billion face what can be
called economic water shortage. The situation is only expected to worsen
as population growth, climate change, investment and management
shortfalls, and inefficient use of existing resources restrict the
amount of water available to people, according to Worldwatch Institute's
Vital Signs Online service (www.worldwatch.org).
It is estimated that by 2025, 1.8 billion people will live in countries
or regions with absolute water scarcity, with almost half of the world
living in conditions of water stress.
Water scarcity has several
definitions. Physical scarcity occurs when there is not enough water to
meet demand; its symptoms include severe environmental degradation,
declining groundwater, and unequal water distribution. Economic water
scarcity occurs when there is a lack of investment and proper management
to meet the demand of people who do not have the financial means to use
existing water sources; the symptoms in this case normally include poor
infrastructure.Large parts of Africa suffer from economic water
scarcity.
World population is
predicted to grow from 7 billion to 9.1 billion by 2050, putting a
strain on water resources to meet increased food, energy, and industrial
demands. But there are many other pressures, including increased
urbanization and overconsumption, lack of proper management, and the
looming threat of climate change. According to the United Nations Food
and Agriculture Organization and UN Water, global water use has been
growing at more than twice the rate of population increase in the last
century.
At the global level, 70
percent of water withdrawals are for the agricultural sector, 11 percent
are to meet municipal demands, and 19 percent are for industrial needs.
These numbers, however, are distorted by the few countries that have
very high water withdrawals, such as China, India, and the United
States.
Agricultural water
withdrawal accounts for 44 percent of total water withdrawal among
members of the Organisation for Economic Co-operation and Development
(OECD), but this rises to more than 60 percent within the eight OECD
countries that rely heavily on irrigated agriculture. In the four
transitional economies of Brazil, Russia, India, and China, agriculture
accounts for 74 percent of water withdrawals, but this ranges from 20
percent in Russia to 87 percent in India.
Policymakers must introduce
a variety of measures to address global water scarcity. One important
initiative is to support small-scale farmers. Much of the public
investment in agricultural water management has focused on large-scale
irrigation systems. Farmers can also use water more efficiently by
taking a number of steps, including growing a diverse array of crops
suited to local conditions and adopting irrigation systems like "drip"
lines that deliver water directly to plants' roots.
Climate change will affect
global water resources at varying levels. Reductions in river runoff and
aquifer recharge are expected in the Mediterranean basin and in the
semiarid areas of the Americas, Australia, and southern Africa,
affecting water availability in regions that are already water-stressed.
In Asia, the large areas of irrigated land that rely on snowmelt and
high mountain glaciers for water will be affected by changes in runoff
patterns, while highly populated deltas are at risk from a combination
of reduced inflows, increased salinity, and rising sea levels. And
rising temperatures will translate into increased crop water demand
everywhere.
To combat the effects of
climate change, efforts must be made to follow an integrated water
resource management approach on a global scale. This involves water
management that recognizes the holistic nature of the water cycle and
the importance of managing trade-offs within it, that emphasizes the
importance of effective institutions, and that is inherently adaptive.
Further highlights from the report:
- A region is said to face water scarcity when supplies fall below
1,000 cubic meters per person, and absolute water scarcity is when
supplies drop below 500 cubic meters a year.
- About 66 percent of
Africa is arid or semiarid, and more than 300 million people in
sub-Saharan Africa currently live on less than 1,000 cubic meters of
water resources per person.
- According
to UN Water, each person in North America and Europe (excluding former
Soviet Union countries) consumes at least 3 cubic meters per day of
virtual water in imported food, compared with 1.4 cubic meters per day
in Asia and 1.1 cubic meters per day in Africa.
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