Geoscience Reference
In-Depth Information
1
Introduction
1.1 Water Problems and Challenges: An Overview
Water is the most precious resource of the earth because no life is possible
without water. It is essential for the survival and livelihood of every human.
It also regulates ecosystems, grows our food and powers our industry. Hardly
any economic activity can be sustained without water. Undoubtedly, water
plays a vital role in our life. Different dimensions of water functions in society
and nature are (Falkenmark and Rockstrom, 2004): (i) water as
life-support
and hence as a basic need and as a human and animal right; (ii) water as an
economic
commodity in some uses; (iii) water as an
integral part of ecosystem
(sustaining it and being sustained by it); (iv) water as a
sacred resource
; and
(v) water as
an inevitable component of cultures and civilizations
. Thus, water
is the key resource for the human/animal health, socio-economic development,
and the survival of earth's ecosystems. On the other hand, natural ecosystems
also play a crucial role in the availability and quality of water through their
purifying and regulating services, thereby sustaining human development on
the earth. In other words, water has social, economic and environmental
values and is essential for sustainable development (Falkenmark and
Rockstrom, 2004; UNESCO, 2003, 2009). In contrast with many other vital
resources of the earth, there is no substitute for water in most activities and
processes where it is needed!
At present, about 10% of the world's freshwater supplies are used for
maintaining health and sanitation, whereas agriculture accounts for about
70% and industries about 20% of the world's freshwater supplies (Shiklomanov,
1997; Shiklomanov and Rodda, 2003). Food production is the most water-
intensive sector. It has been estimated that about one litre of liquid water gets
converted to water vapour to produce one calorie of food. Every person is
responsible for consuming 2000 to 5000 litres of water every day depending
on one's diet and the method of food production, which is far more than 2 to
5 litres we drink every day (Rodriguez and Molden, 2007). A meat-based diet
requires much more water than a vegetarian diet; for example, we need about
