Introduction
Drinking water is one of the essential requirements
for existence for live beings. Surface and ground water are the
two major sources of drinking water. Drinking water supply in urban
areas is mostly centralised and is mostly from surface sources like
natural or impounded reservoirs. As the population density and usage
levels are comparatively high in urban areas, water agencies construct,
operate and maintain huge surface water dams and reservoirs for
meeting their water demands. However, the individual house holds
in urban areas have their own bore wells/open wells to cater the
water needs other than potable. The no.of such wells is very high
due to high density of the houses. In rural areas, ground water
is the main source of drinking water. In earlier days people use
to collect drinking water from open wells and ponds that belonged
to the community
.
With the advent of bore well technology and the consequent effort
by various water organisations, the scenario of rural water supply
has considerably changed. The traditional methods and practices
are given least importance. Government Organisations have given
priority to provide protected water supply to the villages through
rural water supply scheme. Bore wells are drilled and water from
overhead tanks is distributed through supply mains. Statistics reveal
that about 85% of rural water supply are from the ground water sources.
People are happy with these water supply systems as it entails them
low cost or no cost and freedom from maintenance responsibilities.
New trends in ground water exploration, increased access to drilling
rigs and accessories, combined with the Government policies on subsidised
power supply to agricultural pump sets resulted in massive increase
in the number of Agricultural bore wells. Such localised extraction
of ground water for drinking and irrigation purposes beyond the
recharge potential of the areas resulted in gradual decline in ground
water level.
Indiscriminate exploitation of ground water rendered many bore wells
dry either seasonally or completely. To overcome such a situation,
bore wells and tube wells are drilled to greater depths. This has
further complicated the situation in some areas where higher concentration
of hazardous chemicals such as fluorides, arsenic and nitrates are
observed in these waters, in addition to lowering the water table.
Discharge of untreated effluents into surface water streams and
lakes by industries resulted not only in contaminating these surface
waters but also the ground water bodies. In coastal areas like Chennai,
over exploitation of ground water resulted in sea water intrusion
thereby rendering ground water bodies saline in these areas. Identification
and promotion of simple, reliable and environment friendly technologies
are necessary to overcome the above problems.
Reviving the traditional practices of water harvesting using scientific
methods is a potential option.
In most of the cities, the water supply sector is facing a number
of problems and constraints. The pace of urban development and the
increase in population in the urban areas have resulted in exploitation
of water resources to the extremes. Fresh water sources are being
heavily exploited to meet the demands of urban populace. Frequent
failure of monsoon further makes the situation worse.
As surface water sources fail to meet the ever increasing demands,
ground water reserves are tapped, often to unsustainable levels.
Chennai city and its suburban areas often get affected with water
scarcity during the periods of low rainfall. As the dependence on
ground water increases during such periods the ground water table
depletes faster than normal rate resulting in dry wells and also
the incidences of saline water in certain coastal belts. In addition
to quantity, we also face problems of water quality due to over
extraction of ground water. Unplanned and uncontrolled extraction
of ground water would disturb the hydrological balance along the
coastal areas which results in possible sea water intrusion. Hence,
it is necessary to take up measures to conserve and augment the
renewable water resources in all possible ways. Ground water recharge
by rain water harvesting (RWH) is the simple and cost effective
way. |
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