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INTERNATIONAL YEAR OF FRESHWATER
2003
Global Availability of Freshwater
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Global freshwater consumption rose sixfold between 1900 and
1995 - more than twice the rate of population growth. About
one third of the world's population already lives in
countries considered to be 'water stressed' - that is, where
consumption exceeds 10% of total supply. If present trends
continue, two out of every three people on Earth will live
in that condition by 2025.
-- Kofi Annan, in We The Peoples, 2000 |
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 The
United Nations Environment Programme (UNEP) has been at the
forefront of assessing and monitoring global water resources and
presenting information on their use and management for the past
30 years. UNEP, in collaboration with partners and collaborating
centres, collates and analyses water resource data on a global
basis. Despite a concerted effort to create a comprehensive
database on global water use, however, there remain many gaps in
the information available. Several projects and programmes are
working to fill these gaps. Among them are the Global
International Waters Assessment (GIWA), the Global Programme of
Action for the Protection of the Marine Environment from Land
Based Activities (GPA/LBA), and the Global Environment
Monitoring System Freshwater Quality Programme (UNEP-GEMS/Water),
as well as many other programmes dealing with fresh and
coastal/marine waters within other United Nations agencies and
partners. The current situation reveals that, while there is
significant information on most aspects of water resources in
Europe and North America, there are glaring gaps in some of the
available data for Africa, South America and parts of Asia,
particularly in water quality and quantity.
 As
was the case with its earlier publication on Vital Climate
Graphics, UNEP has compiled this report in order to provide an
easily accessible resource on the state of the world's waters.
The goal of this publication is to produce a clear overview,
through a set of graphics, maps and other illustrations, of the
state of the world's fresh and marine waters. It also
illustrates the causes, effects, trends and threats facing our
water sources, with examples of areas of major concern and
future scenarios for the use and management of fresh, coastal
and marine waters.
Over the past
decade, efforts based on Agenda 21's freshwater management
guidelines in Chapter 18, which address the protection of the
quality and supply of freshwater and the application of
integrated approaches for the development, management and use of
water resources, have focused on the following areas:
- Integrated water
resources development and management;
- Water resources
assessment;
- Protection of
water resources, water quality and aquatic ecosystems;
- Drinking-water
supply and sanitation;
- Water and
sustainable urban development;
- Water for
sustainable food production and rural development; and
- The impact of
climate change on water resources.
A
World of Salt: Total Global Saltwater and Freshwater Estimates
Estimates of global
water resources based on several different calculation method s
have produced varied estimates. Shiklomanov in Gleick (1993)
estimated that:
- The total volume
of water on Earth is ~1.4 billion km3.
- The volume of
freshwater resources is ~35 million km3, or about 2.5% of the
total volume.
- Of these
freshwater resources, ~24 million km3 or 68.9% is in the form
of ice and permanent snow cover in mountainous regions, the
Antarctic and Arctic regions.
- Some 8 million
km3 or 30.8% is stored underground in the form of groundwater
(shallow and deep groundwater basins up to 2 000 metres, soil
moisture, swamp water and permafrost). This constitutes about
97% of all the freshwater that is potentially available for
human use.
- Freshwater lakes
and rivers contain an estimated 105 000 km3 or ~0.3% of the
world's freshwater.
- The total usable
freshwater supply for ecosystems and humans is ~200 000 km3 of
water, which is < 1% of all freshwater resources, and only
0.01% of all the water on Earth (Gleick, 1993; Shiklomanov,
1999).
Global Freshwater Resources: Quantity and Distribution by Region
 Glaciers
and icecaps contain approximately 70% of the world's freshwater,
but groundwater is by far the most abundant and readily
available source of freshwater. This graphic illustrates the
quantity and distribution of the world's freshwater resources in
glaciers and icecaps, groundwater, and in wetlands, large lakes,
reservoirs and rivers.
Glaciers and
icecaps cover about 10% of the world's landmass. These are
concentrated in Greenland and Antarctica and contain ~70% of the
world's freshwater. Unfortunately, most of these resources are
located far from human habitation and are not readily accessible
for human use.
According to the
United States Geological Survey (USGS), 96% of the world's
frozen freshwater is at the South and North poles, with the
remaining 4% spread over 550 000 km2 of glaciers and mountainous
icecaps measuring about 180 000 km3 (UNEP, 1992; Untersteiner,
1975; WGMS, 1998, 2002).
Groundwater is by
far the most abundant and readily available source of
freshwater, followed by lakes, reservoirs, rivers and wetlands:
- Groundwater
represents over 90% of the world's readily available
freshwater resource (Boswinkel, 2000). About 1.5 billion
people depend upon groundwater for their drinking water supply
(WRI, UNEP, UNDP, World Bank, 1998).
- The amount of
groundwater withdrawn annually is roughly estimated at
~600-700 km3, representing about 20% of global water
withdrawals (WMO, 1997).
- A comprehensive
picture of the quantity of groundwater withdrawn and consumed
annually around the world does not exist.
Most freshwater
lakes are located at high altitudes, with nearly 50% of the
world's lakes in Canada alone. Many lakes, especially those in
arid regions, become salty through evaporation, which
concentrates the inflowing salts. The Caspian Sea, the Dead Sea,
and the Great Salt Lake are among the world's major salt lakes.
Reservoirs are
artificial lakes, produced by constructing physical barriers
across flowing rivers, which allow the water to pool and be used
for various purposes. The volume of water stored in reservoirs
worldwide is estimated at 4 286 km3 (Groombridge and Jenkins,
1998)
Wetlands include
swamps, bogs, marshes, mires, lagoons and floodplains. The 10
largest wetlands in the world by area are: West Siberian
Lowlands (780 000-1 000 000 km2), Amazon River (800 000 km2),
Hudson Bay Lowlands (200 000-320 000 km2), Pantanal
(140 000-200 000 km2), Upper Nile River (50 000-90 000 km2),
Chari-Logone River (90 000 km2), Hudson Bay Lowlands in the
South Pacific (69 000 km2), Congo River (40 000-80 000 km2),
Upper Mackenzie River (60 000 km2), and North America prairie
potholes (40 000 km2) (Pidwiny, 1999).
The total global
area of wetlands is estimated at ~2 900 000 km2 (Groombridge and
Jenkins, 1998). Most wetlands range in depth from 0-2 metres.
Estimating the average depth of permanent wetlands at about one
metre, the global volume of wetlands could range between 2 300
km3 and 2 900 km3.
Major River Basins of the World
Rivers form a hydrological mosaic, with an estimated 263
international river basins c overing
45.3% (~231 059 898 km2) of the land surface area of the Earth,
excluding Antarctica (UNEP, Oregon State University et al., in
preparation). The total volume of water in the world's rivers is
estimated at 2 115 km3 (Groombridge and Jenkins, 1998).
Reservoirs are
artificial lakes, produced by constructing physical barriers
across flowing rivers, which allow the water to pool and be used
for various purposes. The volume of water stored in reservoirs
worldwide is estimated at 4 286 km3 (Groombridge and Jenkins,
1998)
Wetlands include
swamps, bogs, marshes, mires, lagoons and floodplains. The 10
largest wetlands in the world by area are: West Siberian
Lowlands (780 000-1 000 000 km2), Amazon River (800 000 km2),
Hudson Bay Lowlands (200 000-320 000 km2), Pantanal
(140 000-200 000 km2), Upper Nile River (50 000-90 000 km2),
Chari-Logone River (90 000 km2), Hudson Bay Lowlands in the
South Pacific (69 000 km2), Congo River (40 000-80 000 km2),
Upper Mackenzie River (60 000 km2), and North America prairie
potholes (40 000 km2) (Pidwiny, 1999).
The total global
area of wetlands is estimated at ~2 900 000 km2 (Groombridge and
Jenkins, 1998). Most wetlands range in depth from 0-2 metres.
Estimating the average depth of permanent wetlands at about one
metre, the global volume of wetlands could range between 2 300
km3 and 2 900 km3.
Global International Water Assessment Tools for Better
Monitoring of the World's Water Resources
 GIWA's
assessment tools for monitoring the world's water resources,
incorporating five major environmental concerns and application
of the DPSIR framework, are now beginning to yield results of
practical use for management decisions.
The
DPSIR Framework (Driving Forces- Pressures- Impacts- State-
Responses)
 The
DPSIR framework is used to assess and manage environmental
problems. This graphic explains the DPSIR process.
Source:
http://www.unep.org/vitalwater/
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