Global Uses of Water
Agriculture (mostly irrigation) 69 %
Industry 23 %
Domestic use (household,
drinking water, sanitation) 8 %
These global averages vary a great deal between regions.
In Africa, agriculture consumes 88 per cent of all water withdrawn for human use, while
domestic use accounts for 7 per cent and industry for 5 per cent.
In Europe, most water is used in industry (54 per cent), while agriculture's share is
33 per cent and domestic use 13 per cent.
Major Water Uses
Agriculture
Almost 70 per cent of all available freshwater is used for agriculture. Pumping of
groundwater by the world's farmers exceeds natural replenishment by at least 160 billion
cubic metres a year.
It takes an enourmous amount of water to produce crops: one to three cubic metres to yeild
just one kilo of rice, and 1,000 tons of water to produce on ton of grain.
Land in agricultural use has increased by 12% since the 1960s to about 1.5 billion hectares.
Pasture and crops take up 37 percent of the Earth's land area.
Current global water withdrawals for irrigation are estimated at about 2,000 to 2,555
cubic kilometres per year.
Poor drainage and irrigation practices have led to waterlogging and salinization of
approximately 10 percent of the world's irrigated lands (30 million hectares of the
world's 255 million hectares of irrigated land) according to the UN Food and Agricultural
Organization (FAO).
A combination of salinisation and waterlogging has degraded another 80 millions hectares.
Agriculture is responsible for most of the depletion of groundwater, along with up to
70 per cent of the pollution. Both are accelerating.
Many of the world's most important grainlands are consuming groundwater at unsustainable
rates. Collectively, annual water depletion in India, China, the United States, North
Africa and the Arabian Peninsula adds up to 160 billion cubic metres a year - an amount
equal to the total annual flow of two Nile Rivers.
Industry
Water withdrawals for industry vary with the level of development:
World: 22% of total water use
High-income countries: 59% of total water use
Low-income countries: 8% of total water use
The annual water volume used by industry is estimated to rise from 752 km3/year in 1995 to
an estimated 1,170 km3/year in 2025.
In 2025, the industrial component is expected to represent about 24% of total
freshwater withdrawal.
Some 300-500 million tons of heavy metals, solvents, toxic sludge, and other wastes
accumulate each year from industry.
Industries based on organic raw materials are the most significant contributors to the
organic pollutant load with the food sector being the most important polluter.
Contribution of the food sector to the production of organic water pollutant:
High income countries: 40%
Low-income countries: 54%
More than 80% of the world's hazardous waste is produced in the United States and other
industrial countries.
In developing countries, 70% of industrial wastes are dumped untreated into waters where
they pollute the usable water supply.
Energy
World energy demand, especially for electricity, will increase greatly during this 21st
century.
Hydropower is the most important and widely-used renewable source of energy it represents
19% of total electricity production. Worldwide there are now about 45,000 large dams in
operation. Canada is the largest producer of hydroelectricity, followed by the United
States and Brazil.
Built to provide hydropower and irrigation water and to regulate river flow to prevent
floods and draughts, they have had a disproportionate impact on the environment.
Collectively, they have inundated more than 400,000 square kilometres of mostly productive
land. Somewhere between 40 and 80 million people have been displaced by dams, forced to
relocate to other , often less productive, land.
A study by the World Commission on Dams, published in 2000, found that large dams have a
very mixed record.
On one hand:
In 140 countries, dams provide cheap hydroelectric power. On a global scale, dams
account for 19 per cent of the world's electricity generation and supply, through
irrigation, almost 16 per cent of the world's food.
Some dams continue to operate after 30-40 years, providing water and electricity.
Hydropower plays a major role in reducing greenhouse gas emissions: developing ½ of the
world's economically feasible hydropower potential could reduce greenhouse gases
emissions by about 13%.
On the other hand:
Large dams have led to the loss of forests and wildlife habitat and the loss of aquatic
biodiversity - both upstream and downstream.
Large dams have, in most cases, systematically failed to assess and account for the range
of potential negative impacts on displaced and resettled communities. With up to 80
million people displaced from their homes and many more living downstream suffering from
unintended effects (eg. Loss of fisheries), mitigation efforts have, for the most part,
been cosmetic and ineffective.
According to the Commission, large dams may be on their way out:
Mini-hydropower plants have proved to be far cheaper to build and more economical to
run than originally forecast; plus they have minimal impacts on the environment.
Better management to reduce the demand for water has great potential to reduce water
stress and hydropower requirements.
Improved systems management, particularly for irrigated agriculture, has tremendous
potential for reducing waste, while increasing the efficiency of irrigation systems.
Demand for Water Increasing
While freshwater supply is limited, demand khas risen as populations grow and consumption
per capita increases.
Global consumption of water is doubling every 20 years, more than twice the rate of human
population growth, while pollution and over-extraction in many regions of the world has
reduced the ability of supplies to meet demand.
During the last 70 years, the global population has tripled, but water withdrawals have
increased over six times.
Since 1940, annual global water withdrawals have increased by an average of nearly 3 per
cent per year, while population growth has averaged between 1.5 and 2 per cent.
According to the United Nations, more than one billion people on earth already lack access
to fresh drink water. If current trends persists, by 2025 the demand for freshwater is
expected to rise to 56 per cent more than the amount that is currently available.
More people mean increased water use and less available on a per capita basis.
In 1989 there was some 9,000 cubic metres of freshwater per person available for human use.
By 2000, that figure had dropped to 7,800 cubic metres and is expected to plummet
to 5,100 cubic metres per person by 2025, when the global population is projected to
reach 8 billion.
The world's six billion people are already using about 54 per cent of all the accessible
freshwater contained in rivers, lakes and underground aquifers.
By 2025 the human's share will be 70 per cent, based on the population increase.
If per capita consumption of water resources continues to rise at its current rate,
humankind could be using over 90 per cent of all available freshwater within 25 years.
Water shortages
Finite water resources are coming under increasing pressure from population growth and
over-use.This number implies an increased demand for freshwater of about 64 billion cubic
metres a year - an amount equivalent to the entire annual flow rate of the Rhine River.
As their populations grow and economies develop, water use rises rapidly.
A country experiences water stress when annual supplies drop below 1,700 cubic metres
per person. When annual water supplies drop below 1,000 cubic metres per person,
the country faces water scarcity for all or part of the year.
• In 1995, 31 countries containing 458 million people faced either water stress or
scarcity.
• By 2025, according to projections made by Population Action International, more
than 2.8 billion people in 48 countries will be facing water stress or scarcity.
• By 2050, the number of water short countries soars to 54, affecting 4 billion people,
or 40 per cent of the projected global population.
The worst hit areas are in the Middle East, North Africa and in sub-Saharan Africa.
Over 200 million sub-Saharan Africans already live in water short countries.
This figure will increase to 700 million by 2025, of whom over half will live in
countries facing severe shortages for most of the year.