water resources

Topics: Water, Narmada Bachao Andolan, Flood Pages: 13 (1653 words) Published: October 14, 2014
WATER RESOURCES

What are water resources?






Water resources are sources of water that are useful or potentially useful

to humans. It is important because it is needed for life to exist. Many uses of water include agricultural, industrial, household, recreational and environmental activities. Virtually all of these human uses require fresh water.

Only 2.7% of water on the Earth is fresh water, and over two thirds of this is frozen in glaciers and polar ice caps, leaving only 0.007% available for human use. Fresh water is a renewable resource, yet the world's supply of clean, fresh water is steadily decreasing.

Water demand already exceeds supply in many parts of the world, and as world population continues to rise at an unprecedented rate, many more areas are expected to experience this imbalance in the near future.

Sources of fresh water





Surface water
Sub-surface water
Desalination
Frozen water

Surface water


Surface water is water in
a river, lake or fresh
water wetland. Surface
water is naturally
produced by
precipitation and
naturally lost through
discharge to the oceans,
evaporation .

Sub-surface water


Sub-Surface water, or
groundwater, is fresh water
located in the pore space of
soil and rocks. It is also water
that is flowing within
aquifers. Sometimes it is
useful to make a distinction
between sub-surface water
that is closely associated with
surface water and deep subsurface water in an aquifer
(sometimes called "fossil
water").

Desalination


Desalination is an artificial process by which
saline water (generally ocean water) is converted
to fresh water. The most common desalination
processes are distillation and reverse osmosis.

Frozen water


An iceberg is a large
piece of freshwater ice
that has broken off from
a snow-formed glacier or
ice shelf and is floating in
open water.

Uses of fresh water


AGRICULTURE
It is estimated that 69%
of world-wide water use
is for irrigation and
growing crops.



INDUSTRIES
It is estimated that 15% of
world-wide water use is
industrial. Major industrial
users include power plants,
which use water for cooling
or as a power source (i.e.
hydroelectric plants), ore and
oil refineries, which use water
in chemical processes, and
manufacturing plants, which
use water as a solvent.



HOUSEHOLD
It is estimated that 15% of
world-wide water use is for
household purposes. These
include drinking water,
bathing, cooking, sanitation,
and gardening. Basic
household water
requirements have been
estimated to be around 50
liters per person per day,
excluding water for gardens .

Threats to fresh water



CLIMATE CHANGE
Climate change will have significant impacts on water resources around the world because of the close connections between the climate and hydrologic cycle. Rising temperatures will increase evaporation and lead to increases in precipitation, though there will be regional variations in rainfall. Overall, the global supply of freshwater will increase. Both droughts and floods may become more frequent in different regions at different times, and

dramatic changes in snowfall and snowmelt are expected in
mountainous areas. Higher temperatures will also affect water quality in ways that are not well understood.

HYDROLOGIC CYCLE






DEPLETION OF AQUIFIERS
Due to the expanding human population competition
for water is growing such that many of the worlds
major aquifers are becoming depleted. This is due both
for direct human consumption as well as agricultural
irrigation by groundwater.
Millions of small pumps of all sizes are currently
extracting groundwater throughout the world. Irrigation
in dry areas such as northern China and India is
supplied by groundwater, and is being extracted at an
unsustainable rate .





Aquifers are
underground rock and
cave systems that hold
water.
The...
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