Accepted Papers - 3.pdf - UNESCO

and weathering also control the water bearing
capacity of laterites. Numerous voids and joints/
fractures present in laterites provide free flow of
ground water whereas lithomargic clay acts as
effective aquiclude.
Perspective of the area
These areas are characterized by inherently
heterogeneous and low yielding formations either
exposed on surface or under moderately thin cover
of soil. The soil is generally fragile and prone to
severe erosion from hill slopes. The soil is deep
black having low permeability that can hold only a
fraction of water that falls on it. The ground water
recharge is mainly through fissures and joints in
exposed rocky strata. Although some of the areas
coincide with high rainfall (2000-3000mm), yet the
high topographic gradient and massive nature of
underlying formations generate a high runoff and
less of ground water recharge. Thus, development
of water table is not very pronounced. Water occurs
only as a small under ground pool in the form of
perched water table along the elevated regions.
However, in moderately sloping areas, the
development of water table is common, but of steep
gradient. The steep gradient leads to outflow of
significant quantity of ground water from higher
level to lower level as effluent base flow into rivers.
Thus, depletion of water level is very quick in dug
wells as well as in bore wells, which results into
water scarcity soon after the monsoon season. These
adverse topographic and hydrogeological conditions
are inconducive for ground water development.
Hence, construction of dug wells and bore wells is
not techno- economically viable.
Measures to Tackle Water Scarcity
The techniques and methods used to
overcome water scarcity vary from region to region
depending upon their specific problems, nature of
terrain, climate, hydrogeological conditions etc.
Some of the appropriate techniques in such areas
are enumerated below;
Rain Water Harvesting
Rainwater harvesting is old concept as far as
India is concerned. Our ancestors had been doing it
according to the means available then. Nevertheless,
slowly with the advent of tap water supply the
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rainwater harvesting has lost its importance. As in
areas where water scarcity has become a common
feature due to inadequate availability of source
water, rainwater harvesting has become most viable
option. It is necessary to resort to long-term
measures in harvesting the rainwater to meet the
daily demand. Though the objective of water
harvesting in most cases is to store water for lean
part of the year it also imparts indirect benefits such
as recharging drinking water wells and hand pumps.
In hilly areas, where water harvesting has been
practiced together with afforestation and other
methods of watershed development and land
improvement, desaturated aquifers have also been
recharged and water is available in abundance from
ground water sources. For the hilltop villages,
especially those included in the list of tanker
villages, the water harvesting system could be the
best solution for meeting the water demand during
the dry months by impounding water in reservoirs.
The other alternatives, such as drilling or digging
wells, are not appropriate. Various methods of water
harvesting are feasible in hilly terrain are as
discussed below.
Roof Top Rain Water Harvesting
This system is useful mainly for drinking
water purposes. The system consists of three
components i.e. collection of rainwater, conveyance
and storage. In this system, rainwater falling on
roof of houses and other buildings is collected and
conveyed through a system of pipes and semicircular
channels of galvanized iron or PVC and is
stored in tanks suitably located on the ground or
underground. The practice is in vogue at the
individual household level in remote hilly areas with
high rainfall and also in some areas of moderate to
low rainfall. This type of tank storage is common
in areas where under ground storage in aquifer is
not feasible. Roof catchments have the advantage
that they can be constructed directly near the users,
if the roof is suitable for this purpose. The amount
of harvested water depends on roof area and its
nature, and rainfall regime.
Masnory Storage Tank
In hilly areas where rainfall is high and
number of rainy days widely spread over long
period, Masonry storage tank structures of various