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Water - A Key Driving Force

  • Independent Consultant on Water & Environment


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Water is the most valuable resource on the earth and
an integral part of the environment. Its availability is
indispensable to the efficient functioning of the biosphere.
Settlement of most of the great ancient civilizations has been
generally associated with a reliable and clean supply of water
with convenient sources. For example, the Egyptians centered
their civilization on the Nile. Mesopotamia (the land between
the Tigris and the Euphrates rivers) was the home of several
important ancient empires. Chinese civilization was located
principally in the Yellow and Yangzi river basins. Since the
dawn of Indian civilization, the Ramayana, Mahabharata, the
Arthashastra by Chanakya (3rd century BC), Puranas, the Vrahat
Samhita (550 A.D), the Meghmala (900 AD), Panini’s Astadhyayi
and various other Vedic, Buddhist and Jain texts contain several
references to the various processes of hydrological cycle and
traditional water harvesting structures and water being revered
as a life giving and sustaining force. The bible quotes, ‘I am
the Alpha and the Omega, the beginning and the end. To the
thirsty I will give water without price’ - Revelation 21:6. In
Islam, the Sharia law in Koran literally translates to laws of
sharing water. Water facilitated relatively rapid transportation
prior to about 1850 C.E. From the late 15th through the 18th
centuries, Europeans explored all the major oceans.
Besides earth, there are evidences of water in a variety
of places in the Universe including: the Moon, Mars, Jupiter’s
moons, comets, and in interstellar clouds. Yet, until today,
it is not clear why there is more water on the Earth than on
the other planets of the solar system. Except for fossil water,
all water on the planet Earth circulates throughout the
atmosphere, geosphere and hydrosphere. Amazingly, less
than 1% of the earth’s water is available for human
consumption. Almost one-quarter of the world population
lacks a safe supply of water and half the population lacks
adequate sanitation. Over 90% of the world’s developing
countries, located in arid and semi-arid areas, are under
higher water stress. Over 50% of the world’s population is
estimated to be residing in urban areas, and almost 50% of
the mega-cities having populations over 10 million are
heavily dependent on groundwater, and all are in the
developing world. Nearly 40% of global food production is
attributed to irrigated abstraction, and 70% of the world
groundwater withdrawals are used for irrigation purposes.
Safe and stable water supply is of vital importance to all
socio-economic sectors development. Water has always been
an important source of power, and remained an essential
component in all kinds of manufacturing processes and one of
the most important components of sustainable development.
It is essential for natural habitat for drinking, cleaning,
agriculture, transportation, industry, recreation, animal
husbandry, and providing electricity for domestic, industrial
and commercial use. On the other hand, extreme events of more
or less water may have an impact not only on the human society
but also on the aquatic and terrestrial environments. Expanding
human activities have greatly impacted the water cycle,
resulting in growing number of global water problems and life-
threatening hazards. Misuses of water resources and poor water
management practices have often resulted in depleted supplies.
Most of the people take water for granted. For many, water
becomes an important factor until one turns on a faucet or
flushes a toilet and don’t find flow of water. Conflicts over
water have become more common among competing water
In recent times, due to increase in population,
urbanization, industrialization and use of chemicals in
agriculture, there is an ever-increasing threat to the quality of
water resource base, resulting in decrease in fresh water
availability. While this crisis is most pronounced in the
developing countries, the developed world and economies in
transition also experience major environmental problems and
human health consequences. The problems also include water
shortages due to imbalances between water demand and
supply, and ecosystem deterioration, caused by improper land
use. Erosion and sedimentation, floods induced by
urbanization, the problem of fresh and salt water interaction
both in the surface water and in the groundwater environment.
The humid tropics and temperate zones, while normally
associated with less dramatic hydrological phenomena than
the arid zones, still remain in the focus of interest. Apart from
these, water resources management problems exist in the fragile
ecosystem of dry lands, wetlands, mountains, coastal zones
and small islands, irrespective of their geographic/climatic
location and land use such as urban, peri-urban and rural areas.
While the urban clusters look for low to moderate
volumes of high-quality water, rural clusters look for large
quantity of high-quality water, in inefficient field distribution
and drainage systems. In many areas of India, due rise in water
demand for irrigation and other purposes, inadequate
availability of surface water supply, groundwater will continue
to be used intensively. Farmers adopt groundwater irrigation
due to apparent reliability of storage offered by mechanized
drilling and pumping, and flexibility of groundwater
exploitation, but remain indifferent about quality unless the
groundwater is saline. Increasing indiscriminate groundwater
use has crossed the sustainable limits. In different parts,
environmental problems are evident, such as; lowering in
groundwater levels, decline in productivity of wells, more
seepage from canals, increasing trend of salinity and
groundwater pollution, intermixing of contaminated water
with fresh water, etc. The problem is also compounded by the
complexities of the interactions among the physical,
hydrological, meteorological and biological environment,
management of the natural and the socioeconomic systems.
Increasing water use and pollution generation has crossed
the sustainable limits in many parts. The story of each region
or city may be different, but the main reasons for the water
crisis are common, such as, increasing demand, zonal disparity
in distribution of water supply, lack of ethical framework,
inadequate knowledge and resources. Thus, the issue of water
Agricultural use Industrial use Domestic use
High income
Low-and Middle-
income countries
8% 8% 11%
Water use worldwide
What if developing countries follow their developed counterparts
management is multidimensional, related to reliable
assessment of available water, its supply and scope for
augmentation, distribution, reuse/recycling, its existing
depletion, degradation, pollution and its protection from
depletion and degradation. However, like surface water
resource management, not much concerted efforts have been
made for management of the hidden underground water
resources. Water supply schemes, generating large amounts
of wastewater, are normally designed and built, without the
required matching drainage networks and wastewater
treatment facilities. So far, water has been managed in a
fragmented way. This fragmentation of approach also impedes
coherent hydrological analyses at regional, continental and
global scales. The incorporation of the social dimension
underlines the need for improved, more efficient management
of water resources and the more accurate knowledge of the
hydrological cycle for better water resources assessment.
Since the latter half of the 20th century, rapid population
growth and expanding human activities have given rise to a
variety of serious water problems at the global, regional, and
local levels. The expression, “the 21st century will be an age of
water,” embodies both the concern that water issues may cause
international conflicts and the hope that these same issues will
promote international cooperation. The growing concern for
the water sector have been echoed repeatedly at several
international forum beginning with the UN conference on the
Human Environment, Stockholm in 1972 to the 3rd World
Water Forum, Kyoto in 2003. United Nations declared the year
2003 as the International Year of Fresh Water. The UN General
Assembly at its 58th session in December 2003 agreed to
proclaim the years 2005 to 2015 as the International Decade for
Action, “Water for Life”, and beginning with World Water Day
- March 22, 2005. To solve the aforesaid water problems,
science-based research efforts must be promoted to clarify the
structural relationship between the water cycle and human
activities, as well as establish a sound and sustainable
relationship between them.
The increasing worldwide pressure on water resources
under anthropogenic and environmental change requires an
integrated multidisciplinary approach to address issues
involving water resources assessment and management; taking
a holistic view of the water resources, considering issues, such
as, the quantity and quality of surface water and groundwater
and their interdependence, freshwater and saltwater interface,
urban growth and changing land use patterns, as well as risks
and hazards of flood and drought; identifying the pertinent
parameters, phenomena, processes and possible changes of the
hydrological cycle, and evaluating the water requirement of
different development alternatives; simultaneously addressing
science and policy, based on reliable physical and socio-
economic information. Enhancement in water availability and
safe water supply will be guided by the policies, plans and
technologies at our disposal, in addition to political, socio-
economical, biological and other factors. Choices based on the
best obtainable detailed scientific information, guided by ethical
considerations, offer the best hope to protect water from
depletion and pollution.
Basic Information
To have further insight on the origin of water in the
universe and on the earth, let us discuss the origin of the
elements hydrogen and oxygen that make up water molecules.
The Big Bang: 10 to 20 billion years ago, the Universe was
in an extremely dense and hot (~10 billion °C !) state that
exploded in what is called ‘The Big Bang’. Eventually, the
Universe expanded and cooled and huge collections of gas
formed into billions of separate galaxies, and billions of stars
formed within each. Many fundamental particles were formed
in the beginning of this process, including the basic building
blocks of all atoms: protons, neutrons, and electrons. The two
lightest elements, hydrogen and helium, were also formed.
Some heavier elements were created in the Big Bang, but only
in very trace amounts, e.g., one lithium atom out of every 10
billion atoms. So how are the heavier elements, such as oxygen,
Stellar Evolution: Stars, which contain mostly hydrogen,
like Sun produce huge amounts of energy from nuclear fusion
in their hot cores. The pressure and temperature is so great in
the core that hydrogen is fused together to form helium. 90 per
cent of a star’s lifetime is spent fusing hydrogen into helium.
Once the hydrogen is used up, helium begins fusing and one
of the by products of that process is oxygen. Depending on the
mass of the star, all the heavy elements up to iron can be created
in succeeding fusion reactions or nucleosynthesis. Due to the
Big Bang created hydrogen and oxygen by nucleosynthesis in
stars, and the fact that these elements are highly reactive
chemically, water should therefore be fairly common in the
Universe. However, only at certain temperatures and pressure,
like those found on Earth, liquid water is expected to be found.
Detecting Water Beyond the Earth
Detecting water in the Universe up to now has been done
almost entirely remotely. The composition of a planet’s
atmosphere and surface can be partially determined by
analyzing the spectrum (a displa y of the intensity o f li ght emitted
at each wavelength) of light emitted or absorbed by the
elements that compose it. A spectroscope splits the light into
its components, like a prism, which shows the different colors
(wavelengths) making up white light. Atoms of a given element
can emit only light of specific wavelengths. Similarly, each type
of molecules has a unique spectrum of light. Thus, if the
spectrum of water is found to be present in the full spectrum
of light that is observed from a given planet, the existence of
water on that planet can be inferred. Water molecules have
been detected in this manner in the atmospheres and the
surfaces of some of the planets. In the last few years, planetary
probes have detected tantalizing evidence that water may exist
on other bodies in our solar system, though in fact no other
planet or moon in our solar system has the amount of liquid
water present on the earth. Specifically, the following is a partial
list of evidence of the existence of water in the universe,
detected spectroscopically and by other means:
Ice on the Moon: Over the last couple of years, spacecraft
orbiting the Moon has indicated the possibilities of a large
amount of subsurface ice there.
Comets: Comets (sometimes referred to as “dirty
snowballs”) are chunks of dust and frozen gases including
water that are in highly oblong orbits around the Sun. As
they near the Sun, the sunlight melts some of the comet’s
material, which results in a long tail.
Mars: Th e spacecraft p hot ogr aphs of the Pla net sho w long
jagged structures that appear to be old rivers and canyons.
Photographs taken recently show stacked boulders,
probably deposited by raging floods. However, the
atmospheric pressure on Mars is now 100 times less than
that of earth, and therefore, water cannot exist as a liquid
there anymore, and possibly much of the water exists as
subsurface ice. There are polar ice caps (composed of
frozen carbon dioxide, but small amounts of water-ice)
that get larger during the Martian winter and smaller in
the summer.
Europa: The Galileo spacecraft orbiting Jupiter has
photographed he surface of one of its moons, Europa,
which appears cracked with many fissures, as if it is made
of ice that freezes and then thaws repeatedly.
Interstellar Clouds: The spectrum of water has been
detected in interstellar gas/dust clouds. Water molecules
in masers in interstellar clouds are stimulated by the
energies of nearby stars.
The Origin of Water on Earth
The earth appears to be unique in the solar system in the sense
that it contains an enormous amount of water, which has
existed in more or less in its present state for billions of years.
To know the reason for this, it is necessary to understand the
processes that governed the formation of the earth and the
evolution of the earth and its atmosphere. According to the
Basic Information
most recent theories of planet formation, two steps govern the
process of planet formation: (i) Gravitational collapse takes
place forming small asteroid like bodies, some as large as 1/
500 of the mass of the earth. The planetesimals begin to collide
and form the larger bodies of the planets; and (ii) when a meteor
hits anything, some of it sticks and some is scattered back into
space by the impact. The lower the density of the material, the
more likely it is to escape. In the early stages, the earth collected
heavier stuff more easily, leaving lighter stuff such as silicon
and water still in orbit about the sun. However, it more
effectively trapped the lighter material during the latter stages
of planet formation.
The formation of the earth probably took a few hundred
million years to be completed, as compared with the time of
about 3.5 billion years since the earth has developed a solid
crust. About the time the earth was formed, the sun became
large enough that the fusion reactions in the sun ignited. This
didn’t happen smoothly, but likely in sputtering way for a
while. Each flaring up of the sun sent streams of particles
sweeping out. If the earth had an atmosphere at this time, it
would have been blown off leaving the earth as a rock with
neither air nor water on its surface. In fact, after the sun
stabilized, the earth went through a process of releasing gases
from its interior in a process called degassing. Over a relatively
short time, around 100 million years, enough material had been
released to form the oceans and to give the earth an atmosphere.
There was no free oxygen in the atmosphere at this time, but it
was a collection of gases, largely ammonia, methane and carbon
dioxide, held to the earth by gravitational attraction.
Fortunately, early in its history, the temperature of the earth
dropped below 212 degrees Fahrenheit, and the water
condensed into the ocean that exists today.
In fact, the mass of water present in the oceans now (about
1024 grams), is about the same as the mass of water that was
contained in the crust when the degassing process started only
a few hundred million years ago. The rate at which water is
being lost today can be estimated by calculating the rate at
which water molecules in the atmosphere are dissociated into
its constituent hydrogen and oxygen. The hydrogen being light
enough easily moves off into space. The net effect of hydrogen
loss decreases the amount of water vapor in the atmosphere.
A good estimate is that 5x1011 grams are lost this way each
year. This amounts to a volume of a cube about 100 yards on a
side. The total water lost to space since the beginning of the
earth thus amounts to about 2x1021 grams, about 0.2 percent of
the water in the oceans. Fortunately, the same geologic
processes that formed the oceans originally replace the water
lost to space.
Why is the water still here on the earth? It has to do
with the changing nature of the atmosphere due to evolution
of life, specifically algae. The algae produced free oxygen
by photosynthesis, which destroyed ammonia and methane,
so called greenhouse gases, just as the sun’s luminosity was
increasing by about twenty five percent. If that hadn’t
happened the oceans would have boiled away long ago. In
fact, human beings are the beneficiaries of an incredible
balancing act, which allowed just enough heat to escape from
the earth to keep the oceans from boiling, but not so much
as to cause the earth to freeze solid. Some of the popular
theories pointing towards most likely contributing factors
to the origin of the Earth’s oceans over the past 4.6 billion
years are as follows:
1. The cooling of hot gases were released causing “out
gassing”, potentially bringing water to Earth.
2. Comets, trans-Neptunian objects or water-rich asteroids
from the outer reaches of the asteroid belt colliding with
a pre-historic Earth may have brought water to the world’s
oceans. Measurements of the ratio of the Hydrogen
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isotopes Deuterium and Hydrogen-1 point to asteroids,
since similar percentage impurities in carbon-rich
chondrites were found to oceanic water, whereas previous
measurement of the isotopes’ concentrations in comets
and trans-Neptunian objects correspond only slightly to
water on the earth.
3. Liquid may have been “locked” in the Earth’s rocks and
leaked out over millions of years.
4. Photolysis. (Radiation can break down chemical bonds
separating liquid from hard mass)
5. Rain and sandstorms may have pooled.
It is quite likely that more than one of these factors
contributed to the vast oceans, covering the Earth’s surface at
the present time. The present coastlines are where they are
because some of the water is locked up in the polar ice caps.
With this introduction to the origins of our planet, let us now
turn to consider how the water exists in/on the earth.
Rain: A valuable resource
Rain and snow are key elements in the Earth’s water cycle,
which is vital to all life on Earth. Rainfall is the main way
through which the water in the clouds comes down to Earth,
where it fills the lakes and rivers, recharges the underground
aquifers, and provides drinks to plants and animals. Rain
does not fall in the same amounts throughout the world or
even in different parts of India. What happens to the rain
after it falls depends on following factors:
The rate of rainfall - A lot of rain in a short period tends
to run off the land into streams rather than soak into the
The topography of the land - Water falling on the land,
hills, valleys, mountains, and canyons drains down and
becomes part of a stream, a lake, or groundwater.
Soil conditions - Dense clay soil makes rain a hard time
soaking into, contrast to the sandy soils in desert areas,
which allow water to be quickly absorbed.
Density of vegetation - Land with plant cover slows the
speed of the water flowing on it and thus helps to keep
soil from eroding.
Amount of urbanization - Ro ads, pavement , an d pa rki ng
lots create impervious areas where water can no longer
seep into the ground, causing runoff water.
Where is Earth’s water located?
About 70 and 75% of the Earth’s surface is water-covered. But
water also exists in the air as water vapor and in the ground as
soil moisture and in aquifers. The same water that existed on
Earth millions of years ago still exists, but, is always in
movement, and the water cycle, also known as the hydrologic
cycle, describes the continuous movement of water on, above,
Basic Information
and below the surface of the Earth. Water can change states
among liquid, vapor, and ice at various places in the water
cycle, over millions of years. Things would get pretty stale
without the water cycle!
When the water around is looked at, water in streams,
rivers, and lakes is seen, which is known as “surface water.”
However, there is much more water stored under the ground
than on the surface. In fact, some of the water seen flowing in
rivers comes from seepage of ground water into river beds.
Water from precipitation continually seeps into the ground to
recharge the aquifers, while at the same time water from
underground aquifers continually recharges rivers through
seepage. The water in the apple eaten yesterday may have fallen
as rain half-way around the world last year or could have been
used 100 million years ago by Dinosaur to give her baby a bath.
About 97% of all Earth’s water is in the oceans. The
balance 3% is freshwater. The majority, about 69%, is locked
up in glaciers and icecaps, mainly in Greenland and Antarctica.
It may be surprising to know that almost all of the remaining
freshwater is below the land surface, as ground water. Of all
the freshwater on Earth, only about 0.3 percent is contained in
rivers and lakes — yet rivers and lakes are not only the most
familiar water, but also the water which is mostly used in
everyday lives.
How much water is there on/in the Earth?
In terms of volume, according to the available estimates, the
water on earth is distributed as follows:
1.35 x1017 cubic meters (97.3%) Oceans
29x1015 cubic meters (2.1%) polar ice and glaciers
8.4x1015 cubic me ter s (0 .6 % ) un der ground aquife rs ( fre sh)
0.2x1015 cubic meters (0.01%) lakes and rivers
0.013x1015 cubic meters (0.001%) atmosphere (water
0.0006x1015 cubic meters (0.00004%) biosphere.
The role of individual components in Earth’s water
turnover depends both on the value of water storage and its
dynamics. Hydrospheric water of different kinds is fully
replenished during this period in the process of hydrological
cycle. Its value varies in a very large range. In hydrology and
water management, based on water exchange characteristics,
the two concepts are often used to assess water resources in a
region: the static, or secular, freshwater storage and renewable
water resources. The static, or secular, storage includes
conventionally the freshwater with the period of full renewal
of many years or decades (large lakes, groundwater, glaciers,
etc.). The renewable water resources include the water yearly
replenished in the process of water turnover on the earth. It is
mainly the river runoff estimated in the volume referred to a
unit of time (m3/s, km3/year, etc.) and formed in the region or
Basic Information
An estimate of global water distribution
Water source Water volume, Water volume, Percent of Percent
in cubic miles in cubic freshwater oftotal water
Oceans, Seas, & Bays 321,000,000 1,338,000,000 96.5
Ice caps, Glaciers, & Permanent Snow 5,773,000 24,064,000 68.7 1.74
Ground water 5,614,000 23,400,000 1.7
Fresh 2,526,000 10,530,000 30.1 0.76
Saline 3,088,000 12,870,000 0.94
Soil Moisture 3,959 16,500 0.05 0.001
Ground Ice & Permafrost 71,970 300,000 0.86 0.022
Lakes 42,320 176,400 0.013
Fresh 21,830 91,000 0.26 0.007
Saline 20,490 85,400 0.006
Atmosphere 3,095 12,900 0.04 0.001
Swamp Water 2,752 11,470 0.03 0.0008
Rivers 509 2,120 0.006 0.0002
Biological Water 269 1,120 0.003 0.0001
incoming from outside, including the groundwater inflow to
the river network. This kind of water resources includes also
the yearly renewable upper aquifer groundwater not drained
by the river systems.
What is river?
A river is surface water flowing over land, due to gravity, from
a higher altitude to a lower altitude. When rain falls on the
land, it either seeps into the ground or becomes runoff, which
flows downhill initially as small creeks, which merge to form
larger streams and rivers, eventually end up flowing into the
oceans. When water flows to a place surrounded by higher
land on all sides, a lake is formed. If a dam is built to check a
river’s flow, a reservoir is formed. In the process of turnover,
the river runoff is not only recharged quantitatively, but its
quality is also restored. So the river runoff, actually represent
the renewable water resources. River water is of great
importance in the global hydrological cycle and supply of fresh
water. River runoff is most widely distributed over the territory
and provides the major volume of water consumption in the
world. In practice, the water availability is assessed by the
estimation of river runoff.
Length of Some Important Rivers
Nile (Africa) : 4,132 miles
Amazon (South America) : 4,087 miles
Yangtze (Asia) : 3,915 miles
Huang He, aka Yellow (Asia) : 3,395 miles
Brahmaputra (India) : 1,800 miles
Indus (India) : 1,800 miles
(Source:, accessed on 9th
October, 2006)
Basic Information
Dynamics of water use (Source:
World Water Use
The agricultural sector is the largest user of water globally
and accounts for about 70% of the total freshwater
abstraction. Presently, industry accounts for 22% of the
global freshwater consumption.
However, water consumption by industries is increasing,
and likely to double over the next two decades. In fact, in high-
income countries, industrial water use already accounts for as
much as 59% of the total fresh water consumption. The volume
of water consumed per year by industry is estimated to be 1,170
km3/year by 2025. People, especially in rural areas, are
increasingly dependent on groundwater up to 2 billion
people, a third of the world’s population rely on it.
The left-side pie chart shows that over 99 percent of all
water (oceans, seas, ice, and atmosphere) is not available for
our uses. And even of the remaining 0.3 percent (the small
brown slice in the top pie chart), much of that is out of reach.
Considering that most of the water that is used in everyday
life comes from rivers (the small light blue slice in the right-
side pie chart), generally, it is only a tiny portion of the available
Notice of the world’s total water supply of about 1,386 million
cubic kilometers, over 96 percent is saline.
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water. The right-side pie shows that the vast majority of the
fresh water available for our uses is stored in the ground (the
large brown slice in the second pie chart).
World Water Turnover
Every year the water turnover on Earth involves 577,000 km3
of water. It is the water that evaporates from the oceanic surface
(502,800 km3) and from land (74,200 km3). The same water
amount falls as atmospheric precipitation (on the ocean 458,000
km3 and on land 119,000 km3). The difference between
precipitation and evaporation from land surface (119,000 -
74,200 = 44,800 km3/year) represents the total runoff of Earth’s
rivers (42,600 km3/year), and a direct groundwater runoff to
the ocean (2200 km3/year). Base flow for major rivers such as
the Mississippi, Niger, and Yangtze comes from groundwater
Periods of water resources renewal on the Earth
World Ocean 2500 years
Ground water 1400 years
Polar ice 9700 years
Mountain glaciers 1600 years
Ground ice of the permafrost zone 10000 years
Lakes 17 years
Bogs 5 years
Soil moisture 1 years
Channel network 16 days
Atmospheric moisture 8 days
Biological water several hours
Surfacewater and groundwater pollution effectively decreases
the quantity of usable freshwater. Many of the world’s lakes,
large rivers, and estuaries have been contaminated with
anthropogenic effluent discharges. One litre of wastewater
pollutes about eight litres of freshwater. Contamination of
surfacewater has led many regions of the world to turn to
groundwater. An estimated 12,000 km³ of polluted water
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worldwide, which is more than the total amount contained in
the world’s ten largest river basins. Therefore, if pollution keeps
pace with population growth, the world will effectively lose
18,000 km³ of freshwater by 2050 - almost nine times the total
amount countries currently use each year for irrigation.
What is ground water?
It may probably be some kind of magic for the kids when they
pull down a handle of a hand pump and cool freshwater comes
out of the ground below their feet. 97% of liquid freshwater is
stored underground in aquifers within a few kilometers of the
earth’s surface almost everywhere, beneath hills, mountains,
plains, and deserts. Water at very shallow depths might be just
a few hours old; at moderate depth, it may be 100 years old;
and at great depth or after having flowed long distances from
places of entry, water may be several thousands of years old..
Ground water is an important part of the water cycle, and is
the part of rainfall that seeps down through the soil until it
reaches rock material that is saturated with water. The ground
above the water table may be wet to a certain degree, but it
does not stay saturated. The unsaturated zone contains air and
some water and support the vegetation on the Earth. The
saturated zone below the water table has water filled in the
tiny pores between rock particles and the cracks of the rocks.
Why is there ground water?
A couple of important factors are responsible for the existence
of ground water:
(1) Gravity: Ground water slowly moves underground,
generally at a downward angle (because of gravity), and
may eventually seep into streams, lakes, and oceans.
(2) The rocks below our feet: The rock below the Earth’s
surface is the bedrock. But Earth’s bedrock consists of
many types of rock, such as sandstone, granite, and
limestone. Bedrocks have varying amounts of void spaces
in them where ground water accumulates and can also
become broken and fractured; creating spaces that can
fill with water. Some bedrock, such as limestone, is
dissolved by water — which results in large cavities that
fill with water. Most of the void spaces in the rocks below
the water table are filled with water. But rocks have
different porosity and permeability characteristics, and
water does not move around the same way in all rocks.
Gravity doesn’t pull water all the way to the center of the
Earth. Deep in the bedrock there are rock layers made of dense
material, such as granite, or material that water has a hard time
penetrating, such as clay. These layers may be underneath the
porous rock layers and, thus, act as a confining layer to retard
the vertical movement of water. Since it is more difficult for
the water to go any deeper, it tends to pool in the porous layers
and flow in a more horizontal direction across the aquifer
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toward an exposed surface-water body, like a river. Often a
large amount of the water flowing in rivers comes from seepage
of ground water into the streambed, depending on region’s
geography, geology, and climate. Ground-water pumping can
alter how water moves between an aquifer and a stream, lake,
or wetland by either intercepting ground-water flow that
discharges into the surface-water body under natural
conditions, or by increasing the rate of water movement from
the surface-water body into an aquifer.
Ground-water aquifers and Water Levels in Wells
When a water-bearing rock readily transmits water to wells
and springs, it is called an aquifer. Sometimes the porous rock
layers naturally remain tilted in the earth. There might be a
confining layer of less porous rock both above and below the
porous layer. This is an example of a confined aquifer. In this
case, the rocks surrounding the aquifer confine the pressure in
the porous rock and its water. If a well is drilled into this
“pressurized” aquifer, the internal pressure might (depending
on the ability of the rock to transport water) be enough to push
the water up the well and up to the surface without the aid of
a pump, sometimes completely out of the well. This type of
well is called artesian.
Wells can be drilled into the aquifers and water can be
pumped out. Precipitation eventually adds water (recharge)
into the porous rock of the aquifer. Seasonal variations in
rainfall and the occasional drought affect the “height” of the
underground water level. The rate of recharge is not the same
for all aquifers, though, and that must be considered when
pumping water from a well. Pumping too much water too fast
as compared to the recharge rate draws down the water level
in the aquifer and eventually causes a well to yield less and
less water and even run dry. In fact, pumping a well too fast
can even cause neighbor’s well to run dry if both are pumping
from the same aquifer. When water levels drop below the levels
of the pump intakes, then wells will begin to pump air - they
will “go dry.”
Ground water serves many purposes
The main uses of ground water include irrigation uses, drinking
water and other public uses, and for supplying domestic water
to people who do not receive public-supply water. In many
areas, the majority of water used for self-supplied domestic
and livestock purposes come from ground-water sources. Fresh
ground water is used for many important purposes, with the
largest amount going toward irrigating crops. Local city water
agencies withdraw a lot of ground water for public uses, such
as for delivery to homes, businesses, and industries, as well as
for community uses such as firefighting, water services at
public buildings, and for keeping local residents happy by
keeping community swimming pools full of water. Industries
and mining facilities also used a lot of ground water.
Basic Information
Groundwater exploitation is regulated mainly through control
of borehole drilling or licensing their pumping. Due to absence
of any pricing mechanism and strict regulation, indiscriminate
groundwater exploitation, its wasteful utilization, and land
disposal of wastes continued. In some places, groundwater is
linked to land ownership while in others it is viewed as a
‘common property’. Some of the important parameters of
interest to the planners and managers are recharge ability of
groundwater; quantity and quality; location of recharge intake
areas; inter-linkage between groundwater and surface water;
sources of pollution, etc.
Water quality
Good quality water is an aqueous solution of carbonates,
bicarbonates, sulphates and chlorides of the alkali metals
and alkaline earths, at low concentration level within the
maximum permissible limit prescribed for drinking water.
The process of induction of objectionable matter in
groundwater and thereby changes in its physical, chemical
and other properties, as to render it unfit for various
purposes, is called pollution. Salinization of groundwater,
an important parameter for judging the quality of water, is
caused by both primary as well as a secondary phenomenon,
connected with the lithology of the rock types, temperature,
climatic conditions of the terrain and hydrography of the
surface basins. Surface water or Groundwater chemically
evolves by interacting with naturally occurring minerals in
the rocks and aquifer and sediments, external pollutant
sources from industrial discharges, urban activities,
agriculture, and internal mixing among different
groundwaters along specific flow-paths. The most common
water-quality problem in rural water supplies is bacterial
contamination from septic tanks, which are often used in
rural areas that don’t have a sewage-treatment system.
Effluent (overflow and leakage) from a septic tank can
percolate (seep) down to the water table and maybe into a
homeowner’s own well.
The physical properties of a groundwater aquifer, such
as thickness, rock or sediment type, and location, play a large
part in determining whether contaminants from the land
surface will reach the ground water. The risk of
contamination is greater for unconfined (water-table)
aquifers than for confined aquifers because they usually are
nearer to land surface and lack an overlying confining layer
to impede the movement of contaminants. Because ground
water moves slowly in the subsurface and many
contaminants adsorb to the sediments, restoration of a
contaminated aquifer is difficult and may require years,
decades, centuries, or even millennia. Deterioration of water
quality has a severe negative impact on ecosystems and
habitats that support plant and animal life; and decreases
the suitability of water for all purposes and increases the
cost of making it available for use.
Basic Information
Broadly categorized sources that can affect water quality
(a) Point Sources: Those readily identifiable at a single
location, such as industries, municipal sewage
treatment plants, septic tanks, combined sewer
overflows and raw sewage discharges.
(b) Non-Point Sources: Those diffuse discharges whose
location can not be identified. The main sources are
agriculture, forestry, mining, construction, urban run-off,
hydrological modifications and residual wastes. Some of
the common non-point sources of contaminants are
fertilisers, farmyard manure and compost used for
Inorganic contaminants found in ground water
Contaminant Sources to ground Potential health and
water other effects
Antimony Natural minerals, Decreases longevity,
municipal waste, alters blood levels of
manufacturing of glucose and cholesterol
glass, flame- in laboratory animals
retardants, exposed at high levels
explosives ceramics, over their lifetime.
batteries, fireworks,
Arsenic Natural processes, Causes acute and chronic
industrial waste, toxicity, liver and kidney
pesticides, smelting damage; decreases
of copper, lead, and blood hemoglobin.
zinc ore.
Barium Occurs naturally Can cause cardiac,
in some lime gastrointestinal, and
stones, sandstones, neuromuscular effects and
and soils. hypertension in humans
andcardiotoxicity in
Beryllium Soils, rocks, coal, Causes acute and chronic
petroleum. Mining toxicity; damage to lungs
operations, processing and bones. Possible
plants, and waste carcinogen.
Cadmium Found in rocks, coal, Causes high blood pressure,
and petroleum. liver and kidney damage,
Mining waste, metal and anemia. Destroys
plating, Industrial testicular tissue and red
discharge, plastic blood cells. Toxic to aquatic
stabilizers, water biota.
pipes, batteries,
paints, pigments,
landfill leachate.
Chloride Saltwater intrusion, Deteriorates plumbing,
mineral dissolution, water heaters, and water-
industrial and works equipment at
domestic waste. high levels.
Chromium Old mining operations Chromium VI is much more
runoff, mineral toxic than Chromium III and
leaching, fossil-fuel causes liver and kidney
combustion, mineral damage, respiratory
leaching, metal damage, internal
plating, cooling hemorrhaging, dermatitis,
tower water additive, and ulcers on the skin at high
cement-plant levels.
emissions, waste
Copper Metal plating, Can cause stomach and
industrial and intestinal distress, liver and
domestic waste, kidney damage, anemia in
mining, and mineral high doses. Imparts an
leaching. adverse taste and significant
staining to clothes and
Cyanide Electroplating, Poisoning is the result of
plastics, steel damage to spleen, brain,
processing, synthetic and liver.
fabrics, fertilizer
Fluoride Geological minerals; High levels can stain or
additive to municipal mottle teeth. Causes
water supplies; crippling bone disorder at
industry, phosphate very high levels.
Basic Information
Iron Natural mineral, Imparts a bitter astringent
rocks, mining, taste to water and a
industrial waste and brownish color to laundered
corroding metal. clothing and plumbing
Lead Industry, mining, Affects red blood cell
plumbing, gasoline, chemistry; delays normal
coal, and water physical and mental
additive. development in babies and
young children. Causes
slight deficits in attention
span, hearing, and learning
in children. Can cause slight
increase in blood pressure in
Manganese Natural mineral Causes aesthetic and
from sediment and economic damage, imparts
rocks or from mining brownish stains to laundry.
and industrial waste. Affects taste of water, and
causes dark brown or black
stains on plumbing fixtures.
Toxic to plants at high levels.
Mercury Industrial waste, Causes acute and chronic
mining, pesticides, toxicity. Targets the kidneys
coal, electrical and can cause nervous
equipment (batteries, system disorders.
lamps, switches),
smelting, and fossil-
fuel combustion.
Nickel Electroplating, Damages the heart and liver
stainless steel of laboratory animals
and alloy products, exposed to large amounts
mining, and refining. over their lifetime.
Nitrate; Natural mineral Causes “blue baby disease,”
Nitrite deposits, soils, or methemoglobinemia,
seawater, which threatens oxygen-
freshwater systems, carrying capacity of the
atmosphere, biota, blood.
fertilizer, feedlots,
and sewage.
Selenium Naturally occurring Causes acute and chronic
geologic sources, toxic effects in animals—
sulfur, and coal. ”blind staggers” in cattle.
Toxic at high doses.
Silver Ore mining and Can cause argyria, a blue-
processing, gray coloration of the skin,
photography, mucous membranes, eyes,
electroplating, and organs in humans and
alloy, solder product animals with chronic
fabrication and exposure.
Sulfate Saltwater intrusion, Forms hard scales on boilers
mineral dissolution, and heat exchangers; can
and domestic or change the taste of water,
industrial waste. and laxative effect in high
Thallium Electronics, Damages kidneys, liver,
pharmaceuticals brain, and intestines in
manufacturing, glass, laboratory animals when
and alloys. given in high doses over
their lifetime.
Zinc Industrial waste, Imparts an undesirable taste
metal plating, to water. Toxic to plants at
plumbing, and high levels.
Organic contaminants found in ground water
Contaminant Sources to ground Potential health and
water other effects
Volatile Industries of plastics, Can cause cancer and
organic dyes, rubbers, liver damage, anemia,
compounds polishes, solvents, blurred vision,
crude oil, insecticides, gastrointestinal disorder,
inks, varnishes, skin irritation,
paints, disinfectants, exhaustion, weight loss,
gasoline products, nervous system damage,
pharmaceuticals, and respiratory tract
preservatives, spot irritation.
removers, paint
removers, degreasers,
and many more.
Basic Information
Pesticides Herbicides, Cause poisoning,
insecticides, numbness, weakness,
fungicides, cancer, headaches,
rodenticides, gastrointestinal
and algicides. disturbance, dizziness.
Destroys nervous
system, thyroid,
reproductive system,
liver, and kidneys.
Plasticizers, Waste disposal, Cause cancer. Damages
chlorinated leaching runoff, nervous and
solvents, leaking storage reproductive systems,
benzo [a] tank, and industrial kidney, stomach, and
pyrene, and runoff of sealants, liver.
dioxin linings, solvents,
pesticides, plasticizers,
components of
gasoline, disinfectant,
and wood preservative.
Microbiological contaminants found in ground water
Coliform Occur naturally in Bacteria, viruses, and
bacteria soils and plants; in parasites can cause
the intestines of polio, cholera, typhoid
humans and other fever, dysentery, and
warm-blooded infectious hepatitis.
Radiological contaminants found in ground water
Gross alpha- Weapons, nuclear Damages tissues and
particle activity; reactors, medical destroys bone marrow.
Beta-particle treatment and
and photon diagnosis, mining
radioactivity radioactive material,
and radioactive
geologic formations.
Combined Historical industrial- Causes cancer in the
radium-226 and waste sites are the bone and skeletal
radium-228 main man-made tissue.
agricultural purposes, and land-disposed industrial
effluents from brick kilns, plating, galvanising, rayon
manufacture, rubber processing, pickling, and iron and
steel production. Regular applications of nitrogenous
fertilisers, phosphate fertilisers (which contain ~1-3% F),
fumigants, rodenticides, insecticides and herbicides
containing fluoride as impurity or constituent, and other
such agrochemicals, as well as indiscriminate disposal
of wastes, are likely to create a blanket non-point source
of contaminants.
A wide variety of chemical and physico-chemical
processes, such as, denitrification, precipitation, dissolution,
hydrolysis, transformation/degradation, complex formation,
redox equillibria, colloid formation, diffusion, dispersion,
convection and sorption/desorption, can be expected to alter
the quality of groundwater. In a watershed, gradients in
groundwater quality and contaminant levels can have a variety
of configurations, depending locally on both transient and
steady state variables, such as geological, geomorphological,
hydrological, mineralogical, depth to confinement, weathering
history and other related features. These include: (1) changes
in contaminants concentration in recharging groundwaters
over time, and (2) the distance, direction and time between
recharge and discharge of contaminated groundwaters, and
the distribution and effectiveness of natural remediation.
Water properties
Pure water is virtually colorless and has no taste or smell. But
the qualities of water make it a most interesting. Water’s
chemical description is H2O that is one atom of oxygen bound
to two atoms of hydrogen. The hydrogen atoms are “attached”
to one side of the oxygen atom, resulting in a water molecule
having a positive charge on the side where the hydrogen atoms
are and a negative charge on the other side, where the oxygen
Basic Information
atom is. Due to opposite electrical charges, water molecules
attract each other, and tend to clump together making it kind
of “sticky.” The side with the hydrogen atoms (positive charge)
attracts the oxygen side (negative charge) of a
different water molecule. This is why water
drops are, in fact, drops! Water’s melting and
boiling points are higher than that of similar
compounds. It is unusually viscous based on
its comparatively small molecular weight.
Water has the ability to act as either an acid or a base depending
on the circumstances, and by its nature it is perfectly neutral.
Though polar in its make up, it exhibits
properties that indicate a sort of polymerizing
link between its molecules. While it exists on
earth in all three basic states, solid, liquid, and
gas; water’s properties are often bizarre by
most standards. For example liquid water
contracts when cooled until it reaches a
temperature of about 40Celsius where it
reaches its maximum density. When this
temperature is reached liquid water begins to
expand, and even with a change in state to ice,
water continues to expand, by reducing its
density as its temperature decreases. Water
reacts with more substances than any other
compound. It reacts physically with several compounds to add
to their crystal structure. Compounds like copper and
magnesium sulfate are two examples of many compounds that
almost always found in nature with water molecules physically
attached to their crystal structure. These compounds are natural
dehumidifiers, dependent on water to complete their structure.
Many organic compounds get their oxygen and/or hydrogen
from reactions with water. Water molecules have a unique
ability to be energized by microwave radiation, and at the same
time make an excellent barrier to nuclear radiation. It absorbs
neutrons in nuclear power plants, yet is easily heated by
Water as a solvent
Water is called the “universal solvent” because it dissolves
more substances than any other liquid. When water is the
solvent, the solution is said to be an aqueous solution. In water,
the molecules are held close together by hydrogen bonding
that cause water to exist as a liquid at the temperatures and
pressures that normally prevail on the Earth’s surface. Life
depends on this property. Since there is so much water in living
organisms, water is a very important solvent. Substances such
as glucose dissolve in the water of the blood, which allows it
to be carried around the human body. In plants, the most
commonly transported substance is sucrose, which is also
soluble in water. Water plays a very significant role in our
sleeping course. Our body is mostly made up of water, and it
will not function well if there is insufficient supply of it in the
system. In a day, 10 to 12 cups of water is lost from our body!
So, if the water lost is not replaced, blood clusters together and
becomes powerless to carry adequate amount of oxygen to all
parts of the body, making the body feel frail, declining the
ability to ponder or think well, and reducing the energy level
at minimum. Worst of all, it would lower the body’s resistance
against stress, sickness, or diseases as a result of a weak immune
system. If the body is dehydrated, blood flow to our
fundamental organs would dwindle during sleep.
Furthermore, having an adequate amount of water in the body
helps normalize the body temperature rhythm.
Thermal capacity
Water is also extremely useful due to its high heat capacity;
that is, a large amount of heat energy is required to raise the
Basic Information
temperature of water. It has an enormous ability to absorb and
transmit energy, because, much of the energy is used to break
the hydrogen bonds, which restrict the mobility of the
molecules. As a result, water is relatively slow to heat up or
cool down. In fact, the specific heat capacity of liquid water is
the highest of any known substance. The latent heat (enthalpy)
of fusion of water (the heat energy needed to melt ice) is
unusually high. Therefore, relatively large amounts of heat
energy must be extracted from liquid water before it freezes.
For example, the amount of energy to melt 1 kg of ice at 00C
would be enough to lower the temperature of 1 kg of
Aluminum over 5700 C. The latent heat of vaporisation of water
(the heat energy required to vaporise liquid water) is also
unusually high, and thus has a remarkable cooling effect. Most
liquids contract on cooling, reaching their maximum density
at their freezing point. Water is unusual in reaching its
maximum density above its freezing point - at 4°C. So when
water freezes the ice formed is less dense than water and floats
on top. Ice on the surface effectively insulates the water below,
thereby making it less likely that the bulk of water (sea, pond
or lake) will freeze up even if the air above is very cold. This
prevents large bodies of water from freezing solid and
contributes to the survival of aquatic organisms.
Cohesion, Adhesion, surface tension and capillarity
The hydrogen bonding of water results in strong cohesive
forces. Due to this, the surface of a water drop assumes the
smallest possible area, and forms a sphere. At the surface of
water, the molecules are orientated such that most hydrogen
bonds point inwards towards other water molecules. This gives
water a very high surface tension, higher than any other liquid
except mercury. The ability of water to cling readily to other
molecules is responsible for the upward movement of water
when a small-bore tube is dipped into it. This phenomenon is
called capillarity. Theoretically, plant xylem vessels (dia.
0.02mm) can support a water column of height 1.5m by
capillarity forces. One of its main biological effects is the
upward movement of water in the soil. Without sufficient water
at appropriate time most new technological inputs such as
HYVs, fertilizers are relatively ineffective. Water shortages
severely affect crops by reducing seed germination, seedling
emergency, photosynthesis, respiration, leaf number and seed
number and seed filling. Water stress limits the limits the
metabolism of nitrogen and other nutrients in crops.
Water Facts
Most of the earth’s surface water is permanently frozen
or salty. Complete melting of polar ice caps would rise
the oceans about 240 ft above its present level.
If all the world’s water were fit into a gallon jug, the fresh
water available for us to use would equal only about one
Showering, bathing and using the toilet account for about
two-thirds of the average family’s water usage.
The average person needs 2 quarts of water a day.
Approximately 66% of the human body consists of water.
The total amount of water in the body of an average adult
is 37 litres.
Human brains are 75% water; Human bones are 25%
Human blood is 83% water.
A person can live about a month without food, but only
about a week without water. If a human does not absorb
enough water dehydration is the result.
Basic Information
A person must consume 2 litres of water daily to live
healthily. Humans drink an average of 75.000 litres of
water throughout their life.
It takes enourmous amount of water to produce crops:
one to three cubic metres to yield just one kilo of rice, and
1,000 tons of water to produce on ton of grain.
About 6,800 gallons of water is required to grow a day’s
food for a family of four.
1000 tons of water is required to produce one ton of wheat.
2,000 tons of water is required to produce one ton of rice.
95% of a tomato is water. 85% of a potato is water. 80% of
a pineapple is water.
Each day the sun evaporates a trillion tons of water.
A single tree will give off 265 liters of water per day in
An acre of corn will give off 15,000 litres of water per day
in evaporation.
It takes almost 49 gallons of water to produce just one
eight-ounce glass of milk. That includes water consumed
by the cow and to grow the food she eats, plus water used
to process the milk.
A small drip from a faucet can waste as much as 75 litres
of water a day.
Humans daily use about 190 litres of water.
Two thirds of the water used in a home is used in the
To flush a toilet we use 7.5 to 26.5 litres of water.
In a five-minute shower we use 95 to 190 litres of water.
To brush your teeth you use 7.5 litres of water.
Only 30 per cent of the world’s people have a guaranteed
supply of treated water. The remaining 70 per cent depend
on wells; bore holes and other uncertain sources of water
supply, all liable to contamination.
In a 100-year period, a water molecule spends 98 years in
the ocean, 20 months as ice, about 2 weeks in lakes and
rivers, and less than a week in the atmosphere.
Amount of time that groundwater, once polluted, can
remain polluted: several thousand years.
Source:; http://
www. (accessed on 9th
October, 2006)
In Africa, agriculture consumes 88% of all water, while
domestic use accounts for 7% and industry for 5%. In
Europe, 54% of water is used in industry, 33% in
agriculture and 13% for domestic use.
Almost 70% of all available freshwater is used for
agriculture. Current global water withdrawals for
irrigation are estimated at about 2,000 to 2,555 cubic
kilometres per year.
Pumping of groundwater by the world’s farmers exceeds
natural replenishment by at least 160 billion cubic metres
a year.
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.
In developing countries, 70% of industrial wastes are
dumped untreated into waters where they pollute the
usable water supply.
Basic Information
More than one billion people on earth already lack access
to fresh drink water. If current trend persists, by 2025,
the demand for freshwater is expected to rise to 56%,
exceeding the amount that is currently available.
By 2000, available freshwater per person dropped to 7,800
cubic metres from 9,000 cubic metres in 1989, and is
expected to plummet to 5,100 cubic metres per person by
2025, when the global population is projected to reach 8
The world’s six billion people are already using about
54% of all the accessible freshwater contained in rivers,
lakes and underground aquifers. By 2025 the human’s
share will be 70%, 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% of all available freshwater within 25 years.
By 2025, according to projections, more than 2.8 billion
people in 48 countries will be facing water stress or
By 2050, the number of water short countries soars to 54,
affecting 4 billion people, or 40% 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.
Source: (accessed on 19th
October, 2006)
International Scenario
Water resources distribution over the territory of the Earth
is uneven. The total water resources renewal in the
world is estimated of the order of 43750 km3/year, distributed
throughout the world according to the climates and
physiographic structures. At the continental level, America has
the largest share of the world’s total freshwater resources with
45%, followed by Asia with 28%, Europe with 15.5%and Africa
with 9%. The largest renewable water resources are concentrated
in six principal countries of the world: Brazil, Russia, Canada,
USA, China, and India. Nine countries are the world giants in
terms of internal water resources, accounting for 60% of the
world’s natural freshwater. In terms of absolute value, the largest
exploitable renewable water resources are characteristic of Asia
and South America (respectively, 13,500 and 12,000 km3 pe r yea r).
The smallest are typical for Europe and Australia with Oceania
(respectively, 2900 and 2400 km3 per year). For individual years,
the values of water resources can vary in the range of ±15-25% of
their average values. The specific water availability, i.e., actual
per capita renewable water resources without water consumption,
decreases as population and water consumption grow.
(Note: 1 km3 = 109 m3 = 1 billion cubic metre (BCM) = 0.10 million ha m.)
Due to rapid growth in Earth’s population since 1970
to 1994, the potential water availability of Earth’s population
decreased from 12.9 to 7.6 thousand m3 per year per person.
The greatest reduction of per capita water supply took place
in Africa (by 2.8 times), Asia (by two times), and South
America (by 1.7 times). The water supply of European
population decreased for that period only by 16 %. About
60-70% of this runoff is mainly formed during the flooding
period. In terms of resources per inhabitant in each
continent, America has 24000 m3/year, Europe 9300 m3/year,
Africa 5 000 m3/year and Asia 3 400.1 m3/year. At country
level, there is an extreme variability: from a minimum of 10
m3/inhabitant in Kuwait to more than 100000 m3/inhabitant
in Canada, Iceland, Gabon and Suriname. For 19 countries
or territories, the water resource per inhabitant are less than
500 m3; and the number of countries or territories with less
than 1000 m3/inhabitant is 29. The ten poorest countries in
terms of water resources per inhabitant are Bahrain, Jordan,
Kuwait, Libyan Arab Jamahirya, Maldives, Malta, Qatar, Saudi
Arabia, United Arab Emirates and Yemen.
Global water availability per person
The information on the specific water availability, for all
economic regions and selected countries for the 1950-2025
period, suggest that e.g., the greatest water availability of 170-
180 thousand m3 per capita for 1995 was in the regions of
Canada with Alaska and in Oceania. At the same time, in
densely populated regions of Asia, Central and South Europe,
and Africa the present water availability is within 1.2-5
thousand m3 per year. In the north of Africa and on the Arabian
Peninsula, it is as much as 0.2-0.3 thousand m3 per year. It is
worth mentioning that water availability of less than 2000 m3
per year per capita is considered to be very low, and less than
1000 m3 per year catastrophically low. The thresholds of 1000
and 500 m3/inhabitant correspond respectively to water stress
and water scarcity levels.
Regional Overview
In general, the water resources estimated on the basis of surface
water flows, the countries of the world could be broadly
grouped into ten regions composed of various sub-regions. Of
most importance for water supply is the basic runoff; which is
stable, with little variation during a year and year-to-year. Its
value is approximately 37% of the total volume of global river
runoff, or about 16,000 km3 per year. Many regions are
characterized by an extremely uneven river runoff distribution,
and 60 to 80% of annual runoff takes place during 3-4 months.
For instance, 64% of annual runoff passes during three flooding
months in the north and south of the European part of the
Former Soviet Union (FSU); 57% in the central part of North
America and in southern Asia; 59% in Siberia and the Far East;
68% in Australia, and 80% in western Africa. While, the river
runoff for the low flow period, lasting 3-4 months, amounts to
only 8-9% of annual runoff in the north of the European
territory of the FSU, Canada and Alaska, North China and
International Scenario
Mongolia; 6.7% in Central America; 4-5% in Siberia and the
Far East, and Southern Asia, and as much as 0.8% in Western
Africa. In almost all regions of the world, unevenness of river
runoff distribution during a year leads to the necessity of its
regulation by creating reservoirs of different types.
Region 1: Northern America - The region, extending over
about 21 million km2, covers 16 % of the world’s land area,
and can be divided into three subregions: (i) Alaska, Canada
and Greenland; (ii) Mexico; and (iii) The United States of
America (conterminous states). Overall, the region is relatively
well endowed with water resources. In Alaska, the annual
precipitation ranges from 1524 to 3810 mm with estimated
natural runoff at 8,01,540 million m3/year to less than 127 mm
in the arctic region. Canada (area of 9.98 million km2), the
second largest country in the world has about 9% of the world’s
freshwater resources. Freshwater bodies cover 7.6% of its area.
The annual precipitation decreases in a northerly direction from
500 mm in the central area to 125 mm in the arctic islands.
Canada has more than 31,000 freshwater lakes, ranging from 3
km2 to more than 100 km2. The Great Lakes store 22,700 km3 of
freshwater, 99% of which is a remnant from the glacial period
and so non-renewable. The United States of America has total
area of 9.36 million km2, and taken as a whole, the conterminous
states receive an average of about 762 mm of precipitation
annually. This region is the home to 7% of the world’s
population; the water resources per person exceed 16000 m3/
year, much higher than the world average.
Region 2: Central America and Caribbean - The region,
occupying about 0.73 million km2 or 0.6% of the world’s total
land area, can be divided into the following subregions: (i)
Central America, occupying 72% of the region, with
precipitation increasing from north to south and from west to
east; and (ii) Caribbean (total area of 0.19 million km2)
Renewable water resources and water availability by continents
Continent Area, Population Water resources, Potential water
million (million) (km3 /year) availability,
km21000m 3 /year
Average Max Min Cv per per
Europe 10.46 685 2900 3410 2254 0.08 277 4.23
North America 24.3 453 7890 8917 6895 0.06 324 17.4
Africa 30.1 708 4050 5082 3073 0.10 134 5.72
Asia 43.5 3445 13510 15008 11800 0.06 311 3.92
South America 17.9 315 12030 14350 10320 0.07 672 38.2
Australia and Oceania 8.95 28.7 2404 2880 1891 0.10 269 83.7
International Scenario
consisting of the islands: Greater Antilles and the Lesser
Antilles. The average annual rainfall in the subregion is 1141
mm. The region is relatively well endowed with water
resources, and receives 1.4% of the world’s precipitation and
generates 1.8% of its water resources. With 1.1% of the world’s
population, the water resource per person in the region is
estimated at about 11,900 m3/year, about double the world
Region 3: Southern America - The region, covering about
17.8 million km2 or 13% of the world’s total land area, can be
subdivided into the following subregions: (i) Guyana; (ii)
Andean; (iii) Brazil; (iv) Southern. The Guyana occupies 0.47
million km2 (2.1% of the region’s total area) and precipitation
is highest in the south, 1500-2400 mm/year. The Andean
subregion covers 4.72 million km2 and precipitation increases
towards the north. Brazil (area 8547 million km2) covers 48%
of the region and the south of this subregion has rainfall of
1250-2000 mm/year and in the southeast, the rainfall ranges
from 900-4400 mm/year; the central-west has an average
annual rainfall of 1250-3000 mm/year. The northeast has an
average annual precipitation, irregularly distributed, of 750 mm
to less than 250 mm. The north (with an average 1500-3000
mm/year of rainfall) covers almost the whole of the Amazon
River basin. The Southern subregion total area is 4.1 million
km2 (23.2% of the region’s total area). Overall, the region is
relatively well endowed with water resources, receiving 26%
of the world’s precipitation and generating 28% of its water
resources. Home to 5.7% of the world’s population, the water
resource per person in the region is about 35,000 m3/year, well
above the world average. Chile presents an annual water
availability of 63064 m3/inhabitant. Climate characteristics of
the Central and Southern America generate strong inter-
seasonal and inter-annual variation in water resources,
aggravated by meteorological phenomena such as El Niño.
Region 4: Western and Central Europe - The region,
occupying about 3.7% of the world’s total land area and having
8.4% of its population, can be divided into four subregions: (i)
Northern Europe; (ii) Western Europe; (iii) Central Europe; and
(iv) Mediterranean Europe. Overall, water resources are
abundant, with about 2200 km3 in an average year (5% of the
world’s water resources) and 4270.4 m3/inhabitant/year, but
unevenly distributed among countries. The distribution of
precipitation in the region is very diverse, ranging from less
than 300 mm/year in many Mediterranean plains to more
than 3000 mm/year on the coast of the Norwegian Sea. There
are seven main watersheds of more than 1,00,000 km2. The
major one is the Danube Basin (about 8,00,000 km2), which
covers about 17% of the region. On average, river runoff is
about 450 mm/year, varying from less than 50 mm/year in
areas such as southern Spain to more than 1500 mm/year in
various areas of the Atlantic coast and of the Alps. The Danube
River has the largest flow, 205 km3/year. A wide inter-annual
and seasonal variations in runoff characterize the region’s
In 2000, renewable water resources per inhabitant ranged
from less than 40 m3/year in Malta and 992 m3/year in Cyprus
to 1140 m3/year in Denmark, 85,500 m3/year in Norway and
more than 6,00,000 m3/inhabitant in Iceland. Some countries
rely heavily on external water resources and would fall under
the threshold of 1000 m3/inhabitant/year if they had to rely
only on their internal resources: Hungary (less than 600 m3/
inhabitant/year), and the Netherlands (less than 700 m3/
inhabitant/year). The Northern Europe has very abundant
water resources per country and per inhabitant (except
Denmark) and its drainage systems are quite large. The Western
Europe has relatively small rivers. The Mediterranean Europe
has a higher level of water resources per inhabitant than the
Western Europe and Central Europe subregions. However, the
International Scenario
water resources are unevenly distributed in numerous small
basins, among and within countries.
Region 5: Eastern Europe - The region (total area about
18 million km2) includes the Russian Federation and the eastern
European and Baltic states, covering 13.5% of the world’s land
area and accounting for 3.6% of its population. The regional
water availability is characterized by an extreme variability:
from a minimum of 227 m3 per inhabitant in the Republic of
Moldova to more than 29,000 m3 per inhabitant in the Russian
Federation. However, the water resources in the Russian
Federation are very unevenly distributed. In the more densely
populated western part, annual renewable surface water
resources are estimated at about 2000 m3/inhabitant compared
with up to 1,90,000 m3/inhabitant in the Siberian and Far
Eastern regions. Adding the external flow, all the countries of
the Eastern Europe region show total actual renewable water
resources in excess of 2000 m3/inhabitant. Three countries
depend on other countries for renewable water resources: the
Source: Wor ld R es o urc e s 20 00 -2 0 01 , People and Ecosystesm: The Fraying Web of Life, World Resources Institute (WRI)
Washington DC. 2000.
Republic of Moldova for more than 91%, Ukraine for 62%, and
Latvia for 53%. All other countries in the region have more
than 2000 m3/inhabitant/year and four countries have more
than 10,000 m3/inhabitant/year.
Region 6: Africa - The region, occupying 22.4% of the
world’s land area, and 9% of the world’s water, can be divided
into seven climatic subregions on the basis of geography:
Northern Africa; Sudano-Sahelian; Gulf of Guinea; Central
Africa; Eastern Africa; Indian Ocean Islands; Southern Africa.
Northern Africa has very limited water resources, with less
than 10 mm/year on average and faces very severe water
scarcity, with values per inhabitant varying between 200 and
700 m3/year. In terms of internal water resources, it is the
poorest subregion in Africa (1.2% of the continent’s total
internal water resources) and it is the subregion with the highest
percentage of external water resources (63%) due to the Nile
River, which serves only one country. However, the Sahara
has very important fossil groundwater reserves of major
sedimentary aquifers.
The Gulf of Guinea internal resources represent 25% of
the continent’s total water resources, and groundwater acconts
for 30-50% of the subregion’s total water resources. In the
Central Africa, with abundant water resources, represent 48.4%
of the continent’s internal resources and is a major provider of
water to neighbouring subregions. The Eastern Africa has the
Africa’s largest lake (Lake Victoria), yet, the water resources
are limited (6.5% of the continent’s internal resources) In terms
of water resources, after the Democratic Republic of Congo,
Madagascar is the continent’s second richest country. The other
small islands have abundant groundwater resources, scattered
within their territories. The Southern Africa has various major
trans-boundary river basins, and the water resources constitute
7% of the continent’s total. With only 13% of the world’s
International Scenario
population, the region’s water availability is 4979 m³/
inhabitant/year. Considering the region as a whole, transfers
of water from humid to arid zones represent 50% of the water
resources of the arid zones. Another specificity of the region is
the non-renewable important groundwater reserves located in
the large sedimentary aquifers systems (Continental aquifer,
Nubian sandstones, Sahel and Chad watersheds, Kalahari, etc.),
with reserves estimated to be many thousand million cubic
metres. The Libyan Arab Jamahiriya depends heavily on fossil
groundwater to cover its current water demand.
Region 7: Near East - The region can be divided into
subregions: (i) Arabian Peninsula; (ii) Caucasus; (iii) Middle
East. The Near East region covers an area of 6.34 million km2
and includes 250 million people. The region has the lowest per
capita water resources. Precipitation in the region is very low
and variable, and the water resources are particularly sensitive
to drought. While the Near East region covers 4.7% of the
world’s total land area, the water resources are only about 1.1%
of the world’s water. The countries of the Near East region
have less water resources per person than the world average.
The Arabian Peninsula has very limited water resources, with
less than 10 mm/year of rainfall on average, and is in a situation
of very severe water scarcity, with 200 to 700 m3/inhabitant/
year. Some oil-rich countries convert saline water from the sea
or from poor-quality aquifers (brackish water) into drinking
water. The total use of desalinated water in the Near East region
is estimated to be 3.93 km3/year. In absolute terms, Saudi
Arabia, the United Arab Emirates, and Kuwait are by far the
largest users of desalinated water, accounting for 77% of the
total for the region.
Region 8: Central Asia - The region can be divided into
two subregions: Aral Sea countries; and Other countries.
Although the region covers 3.5% of the world’s total land area
and contains 1.3% of its population, its water resources are only
about 0.7% of the world’s WR. The average annual renewable
surface water resources in the Aral Sea Basin are estimated at
116 km3, of which 78 km3 in the Amu Darya Basin and 37 km3
in the Syr Darya Basin. The present day inflow to the Aral Sea
is estimated at 1-2 km3/year from the Syr Darya and 5-10 km3/
year from the Amu Darya.
Region 9: Southern and Eastern Asia - The region
occupies about 20.4 million km2, or 15% of the world’s total
land area. China and India combined together account for about
63% of this area. The region can be divided into five subregions
as follows: (i) Indian Subcontinent; (ii) Eastern Asia; (iii) Far
East; (iv) Southeast Asia; and (v) Islands. In the Indian
Subcontinent (area of 3.96 million km2, or about 18% of the
region’s total area), consisting of a large portion of floodplains
along the Indus and Ganges river basins, about 80% of the total
precipitation occurs during the two monsoon periods: the
southwest monsoon (June-September), which brings most of
the rainfall; and the northeast monsoon (November-March).
The average annual precipitation in the subregion is about 1279
mm, varying from less than 150 mm in the northwest desert of
Rajasthan, India, to more than 10 m in the Khasi Hills in
northeast India.
In the Eastern Asia (area 11.3 million km2 or about 55% of
the region’s total area and 8.4% of the world’s total land area),
the average annual precipitation is 597 mm, varying from less
than 25 mm in the Tarim and Qaidam basins in China to 1520
mm in DPR Korea. In the Far East subregion (area is 0.48 million
km2 or 2% of the total area of the region), the average annual
precipitation is 1634 mm, most falling during the summer
months from June to September. In the Southeast Asia (area
1.94 million km2, or 9.5% of the total area of the region), the
average annual rainfall is 1877 mm, ranging from 500 mm in
International Scenario
the central dry zone in Myanmar and 650 mm in Phan Rang in
Viet Nam to more than 4000 mm in the mountains of Rakhine
in Myanmar and Bac Quang in Viet Nam. In the Islands
subregion (3.0 million km2, or about 15% of the area of the
region), the average annual rainfall is 2823 mm, ranging from
less than 1000 mm in Port Moresby to more than 8000 mm in
some mountainous areas in Papua New Guinea.
The region has quite humid climates (with annual
precipitation above 10 m) in some placesand in other parts, a
very arid climate. As a result, the region shows a very uneven
distribution and use of its water resources. In India, the flow
distribution of selected rivers in the monsoon period represents
75-95% of the total annual flow. In north China, 70-80% of the
annual runoff is concentrated in the rainy season. Overall, the
region is relatively well endowed with water resources. While
occupying 15.8% of the world’s land surface, it receives 22%
of its precipitation and produces 27% of its water resources.
However, in terms of water resources per inhabitant, the Indian
Subcontinent, Eastern Asia and Far East subregions show the
lowest figures while the figures for the Southeast Asia and
Islands subregions are considerably higher than the world
Region 10: Oceania and Pacific - The region covering an
area of 8 million km2 or 6 % of the world’s total land area, can
be subdivided into two subregions: Australia: Australia; and
Other countries. The countries of this region are mostly islands
of very different types. Some of the islands have a tropical
climate governed mainly by the change between the wet season,
with heavy rainfall, and the dry season. About 75% of the total
rainfall occurs during the wet season. This results in a large
difference in the water level in rivers between the wet and the
dry seasons. The large islands such as Australia and New
Zealand have very dry to humid climates. Australia is dry, with
an uneven geographical and seasonal distribution of rainfall.
River flows are highly variable. Australia has one of the world’s
largest aquifer systems, the Great Artesian Basin estimated at
1.7 million km2 and a storage volume of 8.7 km3.
Global Groundwater Situation
Throughout the world, groundwater balance is shrinking day
by day. Groundwater is also critical in supplying the industrial
water demand in most countries. In some of the most populous
and poverty-stricken regions of the world—particularly in
South Asia—groundwater has emerged at the center-stage of
the food-agricultural economy. In regions with high population
density, dynamic tube-well-irrigated agriculture, insufficient
surface water, and inadequate drainage, many consequences
of groundwater problems are becoming increasingly evident.
The most daunting challenges that the world faces in the water
sector are decline in water tables due to overdraft; waterlogging
and salinization; and pollution due to agricultural, industrial
and other human activities. The estimates of 1997 suggest that
the groundwater use for the world as a whole is around 750–
800 km3 annually, which appears modest compared to overall
water availability. But an overwhelming majority of the world’s
cities and towns depend on groundwater for municipal water
Half of the US population draws its domestic water
supply from groundwater. During 1990s, India, China, the US
and Pakistan together used about 325 km3 of gro undwater ev ery
year; and over 35 countries of the world used more than 1 km3
of groundwater annually. In comparison, world’s aggregate
groundwater resources appear abundant. Groundwater, both
stock and flow, constitutes over two-third of the world’s
freshwater resource, if we exclude glaciers and permanent
snow cover. Even if 8% of the 33,000 km3 floodwater that runs
International Scenario
off to the oceans annually recharge the groundwater, we have
a renewable supply of over 2,500 km3 of gr oun dwa ter annually,
which seems several times more than the world uses.
According to FAO’s AQUASTAT, the Russian Federation uses
less than 5% of its 900 km3 of annual recharge; West Africa
uses less than 1%; China’s renewable groundwater supply is
estimated at over 800 km3; but it uses just around 70%; even
India, which has serious overexploitation problems uses only
33% of the estimated annual recharge of some 450 km3.
Urban industrialization is also a major contributor to
urban groundwater problems. In the Fuyang river basin of
North China the water table has fallen from 8 to 50 meters
during 1967–2000 and industries are polluting the upper zones;
in South Korea’s industrial cities such as Seoul, Pusan and
Daegu, water tables have dropped by 10–50 meters over a 30-
year period due to industrial pumping. In the Cheju island,
seawater intrusion in coastal aquifer has been the direct result
of industrial pumping of groundwater. Mexico’s aquifers too
are amongst the most overdeveloped; Guanajuato State, one
of Mexico’s agriculturally dynamic regions, water tables in 10
aquifers are declining at average annual rates of 1.79–3.3
meters/year during recent years. Groundwater problems in
West and South Asia are as pernicious as or even worse than
those in China. Bangkok, Jakarta and Mexico city have been
facing acute problems of land subsidence because of
groundwater depletion. Aquifer pollution—from both point
and nonpoint sources—is becoming extensive worldwide. In
the Gediz basin of Anatolia, Turkey, nonpoint pollutants—
mostly agrochemicals—have polluted the groundwater and the
river downstream. One of the most serious ill effects of
depletion is from seawater intrusion in coastal aquifers as in
Egypt, Turkey, China and India.
Access to an improved drinking water source: Increased
from 77% of the population in 1990 to 83% in 2002. Despite
this progress, still over one billion people have yet to benefit,
International Scenario
(Accessed on 16.10.2006)
with coverage in rural areas lagging seriously behind that in
urban areas, with 95% of the urban population having access
to improved water sources in 2002 compared to 72% of the
rural population. Inadequate water supply and sanitation
affects multiple dimensions of poverty, including health,
education and degradation of the environment. In 2002, about
3,900 children under five died each day because of diarrhea
attributed to unsafe water supplies and poor sanitation and
hygiene. Access to an improved water source would be an
important step toward improving health outcomes.
Indian Scenario
India, with a total area of 3,287,263 Km2, is endowed with
abundant water in the perennial resources of Himalayan
glaciers, the water generated by monsoons, the groundwater
resources and a long coastline. Yet, the actual distribution over
space and time is strongly influenced by a number of climatic
and geographic factors, and freshwater crisis exists in many
parts at different times of a year. Two-third of available
freshwater is lost due to evaporation and runoff into the Sea.
Over the years, the annual per capita availability of renewable
freshwater has shrunk alarmingly, to meet the demands of
different sectors. From around 5,277 cubic metres in 1955 it
dipped to below 1,820 cubic metres in 2001. India is the second
largest water consuming country in the world, after China, and
per capita water consumption is less than the world average
by 7.6%. The domestic sector demand accounts for only 5% of
the annual freshwater withdrawals, and over the next twenty
years is likely to increase from 25 billion m3 to 52 billion m3.
With increasing population and depleting water resources, the
per capita water consumption in India is expected to decrease
at a compound annual growth rate of approximately 1%, during
the period 2003-2006. With increase in industrial production,
water consumption for this sector has grown and will continue
to grow at a rate of 4.2% per year. According to the World Bank,
demand of water for industrial, energy production and other
uses will rise from 67 billion m3 to 228 billion m3 by 2025.
Agriculture remains central to the Indian economy and
is heavily dependent on irrigation. Due to a large annual
regional and seasonal variation in rainfall, agriculture receives
a greater share of the annual water allocation. Water demand
for agriculture in 1990 was 46 mhm, and is likely to go up to 77
mhm by 2025. Irrigation accounts for over 95% of freshwater
withdrawals consumed in several States and roughly 80%
nationwide. India has the largest irrigation infrastructure in
the world, but the irrigation efficiencies are low, at around 35%.
By the yardstick of irrigation efficiency and not by the net area
irrigated, doubtless, groundwater is the most important
resource. Groundwater alone accounts for 39% of the water
used in agriculture and surface water use often comes at the
expense of other sectors such as the industrial and domestic
supply. Over 80% of the rural domestic water comes from
groundwater sources. This dependence on groundwater is
particularly critical where dry season surface water levels are
200 million people do not have access to clean drinking
water. Currently, only 85% of the urban and 79% of the rural
population has access to safe drinking water and fewer still
have access to adequate sanitation facilities. Although, most
urban areas in India are serviced by a municipal water supply
system, usually originating from local reservoirs or canals, or
imported through inter-basin transfer, these schemes often do
not adequately cover the entire urban population and are
inefficient and unreliable with zonal disparity. Since colonial
times and after independence, these systems did not receive
as much attention as desirable, in favor of large dam and canal
irrigation projects, which could provide water to selected parts
of India. Yet, high economic, social and environmental costs
have not provided their overall benefit. Still, in rural areas
where water is scarce, women have to travel long distances to
wells or streams to fetch water.
Physiography: India can be divided into well-defined
regions: (i) The Northern Mountains, comprising the mighty
Himalayan ranges; (ii) the Great Plains, traversed by the Indus
and Ganga-Brahmaputra river systems; (iii) the Central
Highlands, consisting of the Aravalli ranges in the west and
terminating in a steep escarpment in the east. The area lies
between the Great Plains and the Deccan Plateau; (iv) the
Peninsular Plateaus comprising the Western Ghats, Eastern
Ghats, North Deccan Plateau, South Deccan Plateau and
Eastern Plateau; (v) the East Coast, a belt of land of about 100-
130 km wide, bordering the Bay of Bengal land lying to the
east of the Eastern Ghats; (vi) the West Coast, a narrow belt of
land of about 10-25 km wide, bordering the Arabian Sea and
lying to the west of the Western Ghats, and (vii) the islands,
comprising the coral islands of Lakshadeep in Arabian Sea and
Andaman and Nicobar Islands of the Bay of Bengal.
Climate: The great mountain mass, formed by the
Himalayas and its spurs on the North and the ocean on the
South are the two major influences governing the climate. The
first acts as an impenetrable barrier to the influence of cold
winds from central Asia and gives the sub-continent a tropical
type of climate. The second is the source of cool moisture-laden
winds giving it the oceanic type of climate. The Indian climate
ranges from continental to oceanic, from extremes of heat to
extremes of cold, from extreme aridity and negligible rainfall
to excessive humidity and torrential rainfall. The climatic
condition influences to a great extent the water resources
utilization of the country.
Indian Scenario
Rainfall: The main sour ce o f wa ter in the country - an nua l
rainfall including snowfall, is adequate and estimated to be of
the order of 4000 (400 mhm), 75% occurs just in the four
months June to September of the monsoon period and 50%
falling in just 15 days. With an average annual rainfall of 1,170
mm, India is one of the wettest countries in the world.
However, there are large variations in the seasonal and
geographical distribution of rainfall over the country. At one
extreme are areas like Cherrapunji, in the northeast, which
receives each year with 11,000 mm rainfall, and at the other
extreme are places like Jaisalmer, in the west, which receives
barely 100-200 mm of annual rainfall. Though the rainfall over
India is slightly above global average, its erratic and uneven
distribution leads to occasional floods and droughts, in
different parts. Only 28% of annual rainfall is available for
utilization; 70 m ha m surface water and 42 mhm groundwater.
The amount of water that can be actually put to beneficial use
is much less due to the constraints in the technology for storing
water and inter-state issues. The storage capacity of all the
surface water storage reservoirs/tanks, existing, under
construction and contemplated, add up to 40 mhm, which is
only about 60% of the utilizable surface water potential and
meager 3% of the average annual rainfall.
Surface Water Resources: India is endowed with many
rivers. There are 15 major basin (drainage area >20,000 km2),
Water Resources Availability
(In Billion Cubic Metre)
Total Precipitation : 4000
Total Water Availability : 1869
Total Utilisable Water : 1122 (690 SW + 432 GW)
India’s Water Resources : 4% of Global Water Resources
45 medium (2,000 to 20,000 km2) and over 120 minor (<2,000
km2) rivers, besides numerous ephemeral streams in the
western arid region. Over 90% of river flows occur in just four
months. For large-scale analysis of water-resources, the country
is often separated into 19 major river basins that constitute
about 83-84% of the total drainage area. This, along with the
medium river basins, accounts for 91% of the total drainage.
12 are classified as major rivers, whose total catchment area is
252.8 million hectare (m.ha). Of the major rivers, the Ganga-
Brahmaputra-Meghana system is the biggest with a catchment
Rainfall Distribution in India
(Source: India Meteorological Department;
Indian Scenario
area of about 110 m.ha, which is more than 43% of the
catchment area of all the major rivers. The other major rivers
with catchment area of more than 10 m.ha are the Indus (32.1
m.ha.), the Godavari (31.3 m.ha.), Krishna, (25.9 m.ha.) and
the Mahanadi (14.2 m.ha). The catchment area of medium rivers
is about 25 m.ha and the Subernarekha with 1.9 m.ha.
catchment area is the largest among the medium rivers in the
country. The average flood discharge of Ganga is 50,000 cubic
meter per second and that for the Brahmaputra is 60,000 cubic
meter per second.
The resource potential of the country, which occurs as a
natural run-off in the rivers, is about 1869 km3/year, (as per
the basin-wise latest estimates of the Central Water
Commission) including regenerating flow from groundwater
and the flow from neighbouring countries, considering both
Green water represents the fraction
of rainfall that generates soil
moisture and which supports
terrestrial ecosystems. It is not
returned to groundwater and rivers,
but will eventually evaporate or
transpire through plants
4% Water bodies
1% Wetlands
5% Arid, shrub and barren lands
26% Forests
20% Savannas and grasslands
9% Croplands
Blue water represents the fraction of the precipitation that runs into rivers and aquifers,
and that has a potential for withdrawal. Out of this, the environmental water flow is the
amount of water needed to sustain ecosystem services. The rest of the blue water
flow is available for possible societal use.
Return flow
Rainwater partitioning:
Source: Stockholm Environemnt Institute. Sustainable Pathways to Attain the Millenium
Development Goals Assessing the Key Role of Water, Energy and Sanitation. 2005.
surface and ground water as one system. Of which only 690 km3
are considered as utilizable in view of the constraints of the
present technology for water storage and inter-state issues. A
significant part (647.2 km3/year) of these estimated water
resources come from neighbouring countries: 210.2 km3/year
from Nepal, 347 km3/year from China (Chinese data) and
90 km3/year from Bhutan. An important part of the surface
water resources leaves the country before it reaches the sea:
20 km3/year to Myanmar, 181.37 km3/year to Pakistan
(Pakistani information) and 1 105.6 km3/year to Bangladesh.
The Central Water Commission estimates the groundwater
resources at 418.5 km3/year. Part of this amount, estimated at
380 km3/year, constitutes the base flow of the rivers. The total
renewable water resources of India are therefore estimated at
1 907.8 km3/year.
Major River Drainage Basins in India
(Source: Gupta and Deshpande, 2004).
Indian Scenario
1 Indus
2a Ganga
2(b+c) Brahmaputra + Meghna
3 Godavari
4 Krishna
5 Cauvery
6 Pennar
7 East flowing: between
Mahanadi and Pennar
8 East flowing: between
Pennar and Kanyakumari
9 Mahanadi
10 Brahmani-Baitarni
11 Subernarekha
12 Sabarmati
13 Mahi
14 West flowing: Kachchh,
Saurashtra and Luni
15 Narmada
16 Tapi
17 West flowing: Tapi to
18 West flowing: Tadri to
19 Inland drainage in
20 Minor rivers draining into
Bangladesh and Myanmar
The availability of water resources in various river basins
of the country is highly uneven. The utilizable water resource
has been assessed as 1,132 BCM. The Ganga-Brahmaputra-
Meghna system, covering only 33% of the area is the major
contributor to water resource, accounting for about 60% in the
total potential of the various rivers and about 40% of utilisable
surface water resources. In a majority of river basins, the present
utilisation is significantly high and is in the range of 50-95% of
utilisable surface resources. But in rivers such as the Narmada
and Mahanadi, the percentage utilisation is quite low, 23% and
34% respectively. While 32% of the total water resources are
still available in the Brahmaputra basin, and 28% of the total
water resources in the Ganga basin, this availability is merely
0.2% in the Sabarmati basin. Catchments of the western coast
rivers occupy only 3% of the land area, and account for 11% of
the water resources. Thus 71% of water resources are available
to only 36% of the area and the rest 64% of area has to do with
remaining 29% of the water resources.
The inland water resources of the country are classified
as rivers and canals; reservoirs; tanks and ponds; beels, oxbow
lakes, derelict water; and brackish water. The total area of
inland water resources is unevenly distributed over the country
with Orissa, Andhra Pradesh, Gujarat, Karnataka and West
Bengal accounting for more than 50% of the inland water
bodies. Other than rivers and canals, the total water bodies
cover about 7 m.ha. Of the rivers and canals, Uttar Pradesh
occupies the first place with a total length of rivers and canals
as 31.2 thousand km, which is about 17% of the total length of
rivers and canals. The other States following Uttar Pradesh are
Jammu & Kashmir and Madhya Pradesh. Among the
remaining forms of the inland water resources, tanks and ponds
have a maximum area (2.9 m.ha.) followed by reservoirs (2.1
m.ha.). The States of Andhra Pradesh, Karnataka and Tamil
Nadu, West Bengal, Rajasthan and Uttar Pradesh, account for
62% of the total area under tanks and ponds in the country. As
far as the reservoirs are concerned, major States like Andhra
Pradesh, Gujarat, Karnataka, Madhya Pradesh, Maharashtra,
Orissa, Rajasthan and Uttar Pradesh account for a large portion
of the area. More than 77% of area under beels, oxbow lakes
and derelict water lies in the States of Orissa, Uttar Pradesh
and Assam. Orissa ranks first as regards the total area of
brackish water and is followed by Gujarat, Kerala and West
The distribution of water resource potential in the country
shows that as against the national per capita annual availability
of water at 2208 cu.m., the average availability in the
Brahmaputra and the Barak rivers is as high as 16589 cu.m.
while it is as low as 360 cu.m. in the Sabarmati basin. The
Brahmaputra and the Barak basin with 7.3% of geographical
area and 4.2% of population of the country have 31% of the
annual water resources. Per capita annual availability for the
rest of the country excluding the Brahmaputra and Barak basin
works out to about 1583 cu.m. Any situation of availability of
less than 1000 cu.m. per capita is considered by international
agencies as a scarcity condition. Out of 12 major and 48 medium
river basins in India, the government predicts that by 2025 the
deficit river basins will be Ganga, Subernarekha, Krishna, Mahi,
Tapi, Cauvery, Pennar and Sabarmati. The surplus basins
would be Brhamaputra, Barak, Narmada, Brahmani-Baitarani,
Mahanadi, Godavari and Indus.
Renewable water resources of India are about 4% of the
global availability. In India, annual average per capita fresh
water availability dropped from 5,177 cu.m. in 1951 to 1,820
cu.m. in 2001. It is predicted that by 2025, per capita annual
average fresh water availability will be 1,340 cubic metre
approximately. Already, the potential of most river basins is
being exploited beyond 50% and several basins are considered
Indian Scenario
to be water scarce. About 200 million Indians do not have access
to safe and clean water. An estimated 90% of the country’s
water resources are polluted with untreated industrial and
domestic waste, pesticides, and fertilizers. According to the
United Nations Environment Programme, India will be ‘water-
stressed’ before 2005 (a country is considered ‘water-stressed’
if its water availability is between 1000 to 1700 cubic metres
per person). While rural water demand is assessed on an
allocation of 40 litres per capita per day (lpcd), the
corresponding urban demand is against a norm of 135 lpcd.
Population and water availability trends in India
Note : Government projections; increasing secotral demands
planned to be met through new construction
Source: Population Action International 1995; World Bank, 1977a
If the accepted level of allocation (135 lpcd) is to be
sustained in the year 2050, each of the metros will have to search
for fresh sources of water to meet the growing demand. Water
tariffs have remained lowest in the country’s urban centres. In
Delhi, Mumbai and Chennai, water is supplied at Rs 0.5, 1.6
and 2.7 per cubic metre respectively. This means that the rich
pay a fraction (less than 10%) of the actual cost of producing
potable water. Such low tariffs can only encourage wasteful
water utilisation.
Trends in ground-water use, 1950-2000
Ground water is a valuable resource in India, and is vitally
important in supplying water for everyday water needs. India’s
groundwater resources are almost ten times its annual rainfall.
According to the Central Ground Water Board of the
Government of India, the country has an annual exploitable
groundwater potential of 26.5 million hectare-meters. Over 80%
of the domestic water supply in India is dependent on
groundwater. However, groundwater is fast depleting. Water
tables have fallen significantly in most areas at the rate of one
to three meters every year and there is a significant pollution
of groundwater from natural as well as manmade sources.
Nearly 85% of currently exploited groundwater is used only
for irrigation. Groundwater accounts for as much as 70-80% of
the value of farm produce attributable to irrigation. Besides,
groundwater is now the source of four-fifths of the domestic
water supply in rural areas, and around half that of urban and
industrial areas. Furthermore, the estimates suggest that India
is using its underground water resources at least twice as fast
they are being replenished. Already, excessive ground water
mining has caused land subsidence in several regions of Central
Uttar Pradesh.
Ground water is used to irrigate crops and supply homes,
businesses, and industries with water, where surface water
sources are scarce or inaccessible. The majority of ground water
goes towards crop irrigation, with the next largest use being
Indian Scenario
Water quality in major river systems of India
Class A: Water fit for drinking after proper disinfection.
Class B: Water is fit for bathing.
Class C: Water fit for drinking only after proper treatment
Class D: Water fit for fish and wildlife.
Class E: Suitable only for industrial cooling, irrigation, etc.
Source: www.
(accessed on 24th Oct, 2006)
water withdrawn for public-supply purposes, and it provides
over 50 billion gallons per day for agricultural needs. It is the
source of drinking water for about half the total population and
nearly all of the rural population. Groundwater development is
about 106% in Delhi, 94% in Punjab, 84% in Haryana, 60% in Uttar
Pradesh, 41-51% in the western states, 17-30% in the central states,
and 24-60% in the southern states (CGWB, 1998). Against a critical
level of 85%, there are blocks in Gujarat, Punjab, Haryana and
Rajasthan, where over-abstraction is 100-260%. Many areas of
India are experiencing ground-water depletion, a term often
defined as long-term water-level declines caused by excessive
ground-water pumping, which is a key issue associated with
ground-water use.
Extensive urbanization and land use changes in many
parts of India have caused compaction of the top sub-soil and
significant shrinking of the exposed land surface to direct
infiltration of rainfall (Datta, 2000). Groundwater recharge from
rainfall varies widely from region to region and within the parts
of a region, depending on the frequency, intensity and
distribution of rainfall, evaporation, soil clay content and
landuse. In Delhi area, contemporary recharge is very limited
and ranges from <5-30%, with most parts receiving <5%
recharge (Datta et al, 2001). The average recharge from rainfall
has been reported to be 18% in Punjab, 15% in Haryana, 20%
in western Uttar Pradesh, 1-14% in Rajasthan, 8-14% in Gujarat,
11% in the alluvial deposits of Maharashtra, and 8% in Andhra
Pradesh, (Datta, 2000). A comparison of the results for the
Sabarmati basin with those of the Ganga, the Ramganga and
the Yamuna basins in the Indo-Gangetic Plains indicated a
relatively higher efficiency of winter rains in inducing
groundwater recharge [Datta et al, 1979]. Higher potential
evaporation during monsoon months in Sabarmati basin may
be expected to reduce the net groundwater recharge for a certain
amount of water input [Datta et al, 1980a]. The radiocarbon
Indian Scenario
concentrations of confined groundwaters in Gujarat and
Rajasthan indicated significant amounts of fresh water recharge
even in areas far away from the principal recharge areas of
aquifers [Borole et al, 1979].
The volume and level of ground water is decreasing in
many areas of the country due to excessive pumping at a faster
rate than it can be recharged. Over the last three decades, the
rapid expansion in the use of groundwater primarily for
irrigation has contributed significantly to agricultural and
economic development in India. Groundwater irrigation
potential, the number of wells and the number of energized
pump sets have grown exponentially since the early 1950s. With
more than 17 million wells nationwide, groundwater now
supplies more than 50 percent of the irrigated area and, due to
higher yields in groundwater irrigated areas; it is essential for
an even higher proportion of the total irrigated output. The
practice of sale of water, either on cash or on crop sharing basis
has also encouraged rich farmers constructing deep tubewells
Unbalanced groundwater recharge and lowering of the water table: Some
Groundwater over-development in India by region
and over-pumping the groundwater. According to some
estimates, 70-80 percent of the value of irrigated production in
India may depend on groundwater irrigation. Current
projections suggest that the rapid rate of development will
continue until the full irrigation potential estimated to be
available from groundwater is reached in about 2007.
In highly urbanized areas, such as Delhi area, annual
recharge being very small, as compared to the groundwater
withdrawal, water table declined by 2-8 m in different parts
during the last decade and 2-20 m during 1960-2000 (Datta et
al, 2001; Rohilla et al, 1999). In the past two decades, water
table in 77% area of the Punjab State, with exploitation as high
as 98%, has fallen by 25-30 cm a year and is now stationed at
50-60 m. Increase in cropping intensity and replacement of less
water consuming crops with more water requiring crops
yielding better economic return has resulted in more water
demand (Datta, 2000; CGWB, 1998). During the last decade,
groundwater table declined by 0.2-3.0 m in Uttar Pradesh, 3-8
m in Haryana, and 7-10 m in Rajasthan. In different blocks of
the north-western Uttar Pradesh, during 1977-1996, water table
declined from 1m to 10 m. In Gujarat, decline in the
groundwater table increased from 1m y-1 in 1970 to 2-8 m y-1 in
1997 (CGWB, 1998). The water table in the Thar Desert, Gujarat
and parts of peninsular India has sunk by 20-60 metres in the
past 35 years. In Jalgaon district of Maharashtra State, during
1981-1996, water table declined by 13.30 m. Considerable
decline (>4 m) in groundwater table, during 1988-1998, has
been observed in other States also. If ground-water levels
decline too far, then the well owner might have to deepen the
well, drill a new well, or, at least, attempt to lower the pump.
Also, as water levels decline, the water yield may decrease,
more energy is required to lift upto the land surface. Using the
well can become prohibitively expensive.
Indian Scenario
Deterioration of water quality: some case studies
The country is facing a water quality crisis. Water pollution is
a serious problem surface water resource and biological, toxic
organic and inorganic pollutants already contaminate a
growing number of groundwater reserves. With so many
avenues for its contamination, being a universal solvent, water
tends to dissolve anything and everything that comes its way,
thus changing its quality every minute. One water-quality
threat to fresh ground-water supplies is contamination from
saltwater intrusion. Under natural conditions the boundary
between the freshwater and saltwater tends to be relatively
stable, but pumping can cause saltwater to migrate inland and
upward, resulting in saltwater contamination of the water
supply. Due to public ignorance to environmental
considerations and lack of provisional basic social services,
indiscriminate disposal of increasing anthropogenic wastes on
land, into river and unlined drains, and unplanned application
of agro-chemicals and improperly treated sewage water
continued, resulting in excessive accumulation of pollutants
on the land surface. Sub-surface leaching of contaminants from
landfills as well as seepage from canals/river and drains caused
severe degradation of the groundwater, at many places,
exceeding the WHO prescribed maximum permissible limits
in drinking water.
The groundwater in different parts of Delhi has become
considerably vulnerable to pollution with a wide range of
contaminants. Large part of Delhi area is severely affected by
fluoride (<1-16.0 mg l-1) and nitrate (<20-1600 mg l-1) pollution
of groundwater (Datta et al, 1996a, 1997)). Fluoride and nitrate
levels increased by 2-6 times, during the last decade. In Punjab,
Haryana, Gujarat, Maharashtra and Karnataka, groundwater
nitrate level ranges from <25 mg l-1 to 1800 mg l-1, and fluoride
level 1.5-45.8 mg l-1. High concentration of fluoride (1.5-45.8
mg l-1) has been reported from different parts in the other states
also. Highly skewed distribution and wide range of fluoride
and nitrate suggest contamination from both point and non-
point sources. In the absence of known major geological source
of fluoride and nitrate in the NCR, excessive application of
fertilizers and discharges from steel, aluminum, brick and tile
industries, barn yard and silo wastes, and disposal of crop
residues are major causes of pollution.
In West Bengal, the consequences of arsenic
contamination are evident. Trace to excessive amounts of heavy
metals, such as, Zn (3-41 μg/l), Cu (5-182 μg/l), Fe (279-1067
μg/l), Mn (<1-76 μg/l), Pb (31-622 μg/l), Ni (<1-105μg/l), Cd
(<1-202 μg/l) is found mostly in the groundwaters at some
places of Delhi near industrial sites (Datta et al, 1999), Haryana,
Uttar Pradesh, Andhra Pradesh and Madhya Pradesh. Slow
infiltration of agricultural and urban surface run-off, carrying
alongwith pollutants present in agro-chemicals and wastes
generated by human activities, causes contamination (Datta et
al, 1996a, 1997)). Adsorption/dispersion processes in the soil
zone, degrees of evaporation/recharge and lateral inter-mixing
of groundwater determine the level of contaminants in
groundwater. Over-exploitation induced changes in hydraulic
head cause intermixing of contaminated groundwater with
fresh water along specific flow-pathways (Datta et al, 1996),
increasing lateral extension of contaminated groundwater and
decrease in the available fresh water potential. Obviously, limit
of vulnerability to depletion has reached.
Water Demand and Consumption Patterns
Indians consume 470 cubic meters of water per person per year;
Chinese consume 407 cubic meters water per person per year.
In China, one dollar of GNP is produced per every 370 liters of
water; in India 880 liters of water are required. In the USA,
water consumption at 1,606 cubic meters per person per year,
Indian Scenario
Ministry/Institution Portfolio
Ministry of Water Resources Principal agency responsible
for all water in the country
Ministry of Rural Development Watershed development and
water supply in rural areas
Ministry of Urban Development Drinking water supply in
urban areas
Ministry of Power Development of Mega
hydroelectric projects
Ministry of Non-Conventional Development of micro and
Energy Sources mini hydel potential.
Ministry of Environment Quality of surface and
and Forests groundwater
Ministry of Agriculture Providing resources for
irrigation of agricultural
Ministry of Industry Planning and development of
water for industry
Central Pollution Control Board Monitoring and regulation of
industrial water pollution
Central Ground Water Regulation of quantity and
Authority quality of groundwater
Water Quality Assessment Apex body set up by
Authority MoWR and MoEF, yet to start
effective functioning
Present and Future Water Demand
Sector Water Demand in BCM
Year 2050 2025 2010 2000
Irrigation 1072 910 6885 41
Domestic 102 73 56 42
Industry 63 23 12 8
Energy 130 15 5 2
Others 80 72 52 41
Total 1447 1093 813 634
(Source: Standing Sub-committee on assessment of
availability and requirement of water)
a dollar of GNP requires only four liters of water. In the more
water-frugal European Community, where each person
consumes 605 cubic meters of water per year, a dollar of GNP
requires a mere three liters of water. A region where renewable
fresh water availability is below 1700 cubic meters/capita/
annum is a ‘water stress’ region, and one where availability
falls below 1000 cubic meters/capita/annum experiences
chronic ‘water scarcity’. The annual per capita availability of
Water Resources: Country profile - India
Internal Renewable Water Resources(1977-2001, in cubic km)
India Asia
Surface water produced internally 1222 10985
Groundwater Recharge 419 2472
and surface water) 380 2136
(surface water + groundwater - overlap) 1261 11321
Per capita IRWR, 2001 (cubic meters) 1211 3241
Total, 1977-2001 (cubic km) 1897 X
Per capita, 2002 (cubic meters per person) 1822 X
From other countries (cubic km) 647 X
To other countries (cubic km) 1307 X
Year of Withdrawal Data 1990
Total withdrawals (cubic km) 500 X
Withdrawals per capita (cubic m) 592 X
Renewable Water Resources 32.5 % X
Agriculture 92 % X
Industry 3 % X
Domestic 5 % X
Indian Scenario
renewable freshwater in India has fallen from around 5,277
cubic meters in 1955 to 2,464 cubic meters in 1990. Given the
projected increase in population by the year 2025, the per capita
availability is likely to drop to below 1,000 cubic meters i.e., to
levels of water scarcity. If per capita water availability is any
indication, ‘water stress’ has just begun to show in India.
As per the estimation of the National Commission for
Integrated Water Resources Development, the demand in 2010,
2025 and 2050 is likely to be 710, 843 and 1180 BCM respectively,
assuming gradually increase in irrigation efficiency to 60 %
from 35 - 40 % at present. Though water is constitutionally a
state subject, Government policies, multiplicities of activities
and economic incentives have also influenced the water
distribution and consumption across India. While the
Constitution mandates panchayats to control and manage
water at the local level, water remains under the control of a
number of ministries and institutions.
Future Scope
Functions of any area are generally linked to short-term and
long-term land use changes and have consequences on the
water resource. It has been difficult to accurately assess world
water resources and their response to the important factors
of global change, namely: climatic variability; land cover
change, industrialization and population growth; and the
control of the natural water cycle through hydraulic
engineering. Carefully maintained and reliable records of
global hydrologic change to judge the cumulative impact of
human activities on the world freshwater systems are not
available. For example, the public usually has neither any
notion about groundwater quantity nor have any
infrastructure to assess its quality at hand. The common man
judges its availability for general purposes in terms of the
depth to groundwater below the surface and quality in terms
of color, odor and taste, and thus determines their land use
characteristics. Their demands on land and groundwater and
the consequences of these demands have been characterized
scarcely. To manage with the situation, an ad hoc and tactical
approach has been taken. The regulation of groundwater
exploitation is mainly achieved through control of borehole
drilling or licensing their pumping. Due to absence of any
pricing mechanism and strict regulation, indiscriminate
groundwater exploitation, its wasteful utilization, and land
disposal of wastes continued.
Most of the hydro-geological and groundwater
development/protection research has been largely
fragmented, technocratic and relates to groundwater flow
and remediation. The research related to groundwater use
in the social and economic context being relatively small,
the research on its own is of relatively little use for practical
management purposes. Despite the highly technical work
presented in the literature, the status of knowledge of the
aquifer systems is often limited at the level at which a
management response is required. With deterioration in
routine monitoring networks in many parts of the world,
for all practical purposes, an accurate assessment is
extremely difficult. There is a need for detailed studies of
complex drainage basins that collectively represent the
domain over which anthropogenic change and its impact on
water resources and the sustainability of the biosphere can be
reasonably assessed.
To optimize the water-use in the long term, and to protect
and conserve it as required, some of the important aspects
with which water resources managers are confronted,
include characteristics of river water flow, discharges,
groundwater renewal, flow velocity and direction, its
interaction with each other as well as with surface water
bodies, the sources of pollution, trace the movement of
pollutants and containment of spreading from known
sources, quality of water and causes of quality deterioration.
These parameters must be measured under both the steady
and non-steady conditions. Efficient irrigation systems and
water management practices can help reduce the impact of
irrigated production on offsite water quantity and quality.
Producers may reduce water use by applying less than full
crop-consumptive requirements, shifting to alternative crops
or varieties of the same crop that use less water, or adopting
more efficient irrigation technologies. In some cases, the
effectiveness of improved practices such as irrigation
scheduling and water-flow measurement may be enhanced in
combination with other farming practices such as conservation
tillage and nutrient management.
This calls for a thorough scientific knowledge and precise
understanding of the key interaction processes of the system
with the biophysical and hydrological environment, in different
regions and within the parts of a region. Generally, studies on
regional flow systems adopted a hydraulic approach, based
on gravity-induced flow from high to low head. However,
the usual method of water level distribution analyses
provides a short-term feature of the hydraulics. Modeling
can be used to study impacts and trends resulting from
various development options, addressing and simulating not
only economic efficiency and technical merits, but also the
preferences and priorities of stakeholders. Nonetheless,
several opportunities exist for analyzing the global status
of the land phase of the hydrological cycle and associated
water resources. Scope exists therefore to “upscale” local-
scale knowledge to estimate and to develop the hydrological
and water management strategies for ecological, social and
economic sustainability over larger domains. The basin scale
is appropriate for comparing water resources (precipitation,
groundwater, surface water) and water use or water demand
(domestic, industrial, agricultural). However, the mechanisms
that govern water demand are not well outlined and relevant
parameters are yet to be suggested.
Future Scope
There remains much to do in order to obtain sound
statistics on water resources, and particularly standardized data
sets, at global level. Therefore, the methodology used to
compute water resources is intentionally simple and based on
transparent rules. More effort needs to be focused on the
assessment of the variability of water resources in space
(watershed level), in time (dry-year resources) and according
to constraints (exploitable resources). National averages hide
local differences and, for large countries, are of little use for
assessing the country’s water situation. The use of global data
sets (meteorological, etc.) coupled with water-balance models
can contribute to improving the assessment of water resources.
The emergence of improved models, high quality isotopic and
biophysical data, remote sensing imagery, information
technology, higher level of computational capability, and data
assimilation schemes, provide a unique opportunity to monitor
the state of the hydrological cycle over broad domains and in
near-real time, with a much higher spatial and temporal
resolution. In India, isotope techniques and remote sensing
have been used extensively, for over three decades, to
understand the water cycle, surface water status, soil water
movement, groundwater flow regime, recharge and
contamination characteristics, residence time (age) in the
aquifer, groundwater-surface water interactions, groundwater
hydrodynamic zones, flow-pathways and mixing processes in
groundwater system.
Emphasis is now being given also to the nature of water
as an economic resource in global debates. Yet, water tariffs in
many areas are very low for public supply and there is no
mechanism of pricing for extraction of groundwater. The level
of subsidy is extremely high for domestic consumption.
Majority thinks water is available free of cost. This leads to
more consumption and wasteful utilisation, resulting in low
level of revenue collection. This falls far short of covering the
cost of production and hinders the investment capacities of
the public utility. The massive investments required to avoid
pollution, remediate polluted aquifers and control overdraft
prompted the planners, developers and managers to think of
the estimates of the value of groundwater.
With an extremely uneven natural space-and-time water
resources distribution, an intensive man’s activities, and a rapid
population growth, even at the present time a significant fresh
water deficit exists in many countries and regions, especially
during dry years. In the decades to come, the most of Earth’s
population and many countries in the world would have a
critical situation with water supply. Water resources deficit
becomes a factor deteriorating the living standard of population
retarding the economic and social development in most
developing countries of the world. It is already clear that in
the first half of the 21st century the water problem will be of
the most importance even among such global problems of
humankind as food and power production. Scope exists to
cover all levels and aspects of education, information transfer
and training, a clear priority is to be given to higher education,
including institutional capacity building and networking,
education for research at postgraduate level, continuing
professional education and to activities targeting “training of
trainers”, within the domain of education and training.
The central issue is re-defining water governance. To
improve the situation alternative institutional arrangements
have to be examined along with the effective control of the
existing institutions. In the context of groundwater, there is
a need to develop management principles addressing
ecological, equity and sustainability concerns. It is also
desirable to identify, strengthen and provide legal validity to
Future Scope
local institutions, which can ensure equitable and sustainable
use of water, within ecological confines. In addition to the