Geoscience Reference
In-Depth Information
The total volume of water resources on Earth constitutes about 1.4 billion km
3
.
The volume of fresh-water resources is about 35 million km
3
or 2.5 % of the
total water volume.
From these fresh-water resources, about 24 million km
3
or 68.9 % exist in the
form of ice and constant snow cover in mountains, Antarctic and Arctic.
About 8 million km
3
or 30.8 % are under ground in the form of ground waters
(in shallow and deep basins of ground water down to 2,000 m deep). Soil
moisture, bog water, and permafrost.
In fresh-water lakes and rivers there are about 105 thousand km
3
or 0.3 % of
global fresh-water supply.
The general volume of fresh-water supply to be consumed by ecosystems and
population constitutes about 2,000 thousand km
3
, that is, less than 1 % of the
global fresh-water supply.
About 3,011 fresh-water biological species have included in the list of species,
which either are under the threat or disappeared; 1,039 of them being
sh. Four
of the
five existing species of river dolphins and two of the three existing species
of sea-cows as well as about 40 species of fresh-water tortoises and more than
400 species of mollusks in fresh-water are under the threat.
700 km
3
or about 20 %
of the global water diversion. About 1.5 billion people drink ground water.
The annual ground waters diversion is evaluated at 600
-
From estimates, 70 % of the global fresh water was spent in 2,000 on agriculture.
The average per-capita consumption of water in developed countries is about 10
times greater than in developing countries. In developed countries this indicator
varies between 500 and 800
'
/day, and in developing countries
—
from 60 to150
'
/day.
Industry consumes about 20 % of the global fresh-water diversion. From 57 to
69 % of the global water diversion are spent on energy production at hydro and
nuclear power stations, 30
−
40 %
—
in industrial processes, and 0.5
−
3%
—
for
needs of thermal energy.
The fresh-water problems are very broad and diverse. Table
9.3
(WCSDG 2004)
presents a summary of the aspects of these problems onwhich the humans
life support
depends in the context of the UN Millenium Declaradion (UNEP 2002, 2004).
On the whole, it should be stated that provision of suf
'
cient pure water is of
fundamental importance for achieving the goals of the socio-economic development
and environmental protection. In this connection, of serious concern is an enhanced
anthropogenic impact on the environment. So, for instance, the area of fresh-water
wetlands that play an important role in natural puri
cation of water and in the water
cycle formation has almost doubled during the last 20 years. Meanwhile, according
to the economic assessment of the role of wetlands functioning, their losses are
equivalent to 20 thousand dollars per year. About 20 % of 10 thousand species of
fresh-water
fish are either on the verge of extinction or do not exist anymore. The
number of large dams in the world has increased from 5,000 in 1950 to more than
45,000 now, which has led to negative ecological outcomes (Beder 2005; Nguyen
Xuan Man et al. 2010).
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