WATER RESOURCE

Water is an indispensable natural resource on this earth on which all life depends. About 97% of
the earth’ s surface is covered by water and most of the animals and plants have 60-65% water in
their body. The water we use keeps on cycling endlessly through the environment, which we call
as Hydrological Cycle. The water from various moist surfaces evaporates and falls again on the
earth in the form of rain or snow and passes through living organisms and ultimately returns to
the oceans.

Although water is very abundant on this earth, yet it is very precious. Out of the total water
reserves of the world, about 97% is salty water Natural Resources 15 (marine) and only 3% is
fresh water. Even this small fraction of fresh water is not available to us as most of it is locked
up in polar ice caps and just 0.003% is readily available to us in the form of groundwater and
surface water.

Groundwater
About 9.86% of the total fresh water resources is in the form of groundwater and it is about 35-
50 times that of surface water supplies. Groundwater is the water found underground in cracks of
the ground above aquifers. This is located in the fractured rock of the earth below the saturated
zone of the planet.

A layer of sediment or rock that is highly permeable and contains water is called an aquifer.
Layers of sand and gravel are good aquifers while clay and crystalline rocks (like granite) are not
since they have low permeability. Aquifers may be of two types:

Unconfined aquifers which are overlaid by permeable earth materials and they are recharged by
water seeping down from above in the form of rainfall and snow melt.

Confined aquifers which are sandwitched between two impermeable layers of rock or sediments
and are recharged only in those areas where the aquifer intersects the land surface. Sometimes
the recharged area is hundreds of kilometers away from the location of the well.
SURFACE WATER:
The water coming through precipitation (rainfall, snow) when does not percolate down into the
ground or does not return to the atmosphere as evaporation or transpiration loss, assumes the
form of streams, lakes, ponds, wetlands or artificial reservoirs known as surface water. The
surface water is largely used for irrigation, industrial use, public water supply, navigation etc.

WATER USES AND OVER-EXPLOITATION

Due to its unique properties water is of multiple uses for all living organisms. Water is absolutely
essential for life. Most of the life processes take place in water contained in the body. Uptake of
nutrients, their distribution in the body, regulation of temperature, and removal of wastes are all
mediated through water.
Human beings depend on water for almost every developmental activity. Water is used for
drinking, irrigation, transportation, washing and waste disposal for industries and used as a
coolant for thermal power plants. Water shapes the earth’s surface and regulates our climate.

With increasing human population and rapid development, the world water withdrawal demands
have increased many folds and a large proportion of the water withdrawn is polluted due to
anthropogenic activities.

Overuse of groundwater for drinking, irrigation and domestic purposes has resulted in rapid
depletion of groundwater in various regions leading to lowering of water table and drying of
wells. Pollution of many of the groundwater aquifers has made many of these wells unfit for
consumption. Rivers and streams have long been used for discharging the wastes.

Effects of Groundwater Usage

(i) Subsidence: When groundwater withdrawal is more than its recharge rate, the sediments in
the aquifer get compacted, a phenomenon known as ground subsidence. Huge economic losses
may occur due to this phenomenon because it results in the sinking of overlying land surface.
The common problems associated with it include structural damage in buildings, fracture in
pipes, reversing the flow of sewers and canals and tidal flooding.
(ii) Lowering of water table: Mining of groundwater is done extensively in arid and semi-arid
regions for irrigating crop fields. However, it is not advisable to do excessive mining as it would
cause a sharp decline in future agricultural production, due to lowering of water table.
(iii) Water logging: When excessive irrigation is done with brackish water it raises the water
table gradually leading to water-logging and salinity problems.

WATER CONSERVATION
Water being one of the most precious and indispensable resources needs to be conserved. The
following strategies can be adopted for conservation of water.
 i. Decreasing run-off losses: Huge water-loss occurs due to runoff on most of the soils,
which can be reduced by allowing most of the water to infiltrate into the soil. This can be
achieved by using contour cultivation, terrace farming, water spreading, chemical
treatment or improved water-storage system.
 Contour cultivation on small furrows and ridges across the slopes trap rainwater and
allow more time for infiltration. Terracing constructed on deep soils have large water-
storage capacity. On gentle slopes trapped run off is spread over a large area for better
infiltration.
 Water spreading is done by channeling the water-flow is controlled by a series of
diversions with vertical intervals.
 Chemical wetting agents (Surfactants) increase the water intake rates when added to
normal irrigated soils.
 Surface crop residues, Tillage, mulch, animal residues etc. help in reducing run-off by
allowing more time for water to penetrate into the land.
 Water-storage structures like farm ponds, dug-outs etc. built by individual farmers can be
useful measures for conserving water through reduction of runoff.
ii. Reducing evaporation losses.
iii. Reducing irrigation losses. Eg implementing drip irrigation and sprinkler irrigation.
iv. Re-use of water
v. Preventing wastage of water: This can be done in households, commercial buildings and
public places.
 Closing taps when not in use
 Repairing any leakage from pipes
 Using small capacity flush in toilets.
vi. Increasing block pricing.