In this paper, an attempt has been made
at Sweta sub basin, Kallar basin, Tamil Nadu, where sites
for groundwater exploration have been demarcated applying
geophysics and GIS technique using Arc GIS software. In
this paper, the geophysical output was taken to GIS platform,
where the point scoring of the individual theme followed
by the final map was assessed to predict the water bearing
formation. The total work is executed with the weighted
rating analysis in GIS environment. Spatial and non-spatial
data was analyzed in GIS in a quick and efficient way.
The term `geographic' in GIS refers to the locational attributes
which define the spatial positioning of the piece of information
on the face of the earth. The advent of digital computers
with high data processing speed and the development of
analytical tools in GIS have helped in handling geographically
referenced data with ease and flexibility. Of late, computer-aided
GIS has become a reality. Using of GIS in hydrogeology
is only at its inception, but there have been cases of
some successful applications.
Water is fundamental to everyone's existence
and we strongly believe that the best way to foster respect
towards water and the environment is to help people recognize
the importance of conserving water, protecting water resources,
understanding the water cycle, and discovering the interface
between water and other aspects of daily life. Groundwater
resources are dynamic in nature as they grow with the expansion
of irrigation activities, industrialization, urbanization,
etc. As it is the largest available source of fresh water
lying beneath the ground, it has become crucial not only
for targeting groundwater potential zones, but also for
monitoring and conserving this important resource. The
expenditure and labor incurred in developing surface water
is much more compared to groundwater, hence more emphasis
is placed on the utilization of groundwater which can be
developed within a short time. Besides targeting groundwater
potential zones it is also important to identify a good
quality zone.
Electrical resistivity method is useful
to investigate the nature of subsurface formation by studying
the variation in their resistance to flow of electrical
current and hence determine the occurrence of groundwater.
The objective of this method in the field of groundwater
exploration is to locate groundwater bearing formations,
evaluate thickness and lateral extent of aquifers, find
the depth of bed rock, etc. Among the geophysical method,
electrical resistivity has a particular advantage in hydrogeology
as it responds to variations in the conductivity of groundwater
bearing formations. Electrical resistivity method has gained
a considerable importance in the field of groundwater exploration
because of its low cost, easy operation and efficacy in
detecting the water bearing formations. The isoresistivity
contour maps of the region are prepared by contouring the
apparent resistivity values, corresponding to the electrode
spacing (AB/2). These maps are helpful in delineating low
apparent resistivity zones (Narayana and Lokesh, 2000).
The electrical resistivity helps in predicting the best
promising zones for groundwater and also in recommending
the drilling of borewells (Vaidya et al., 2002).
Khan and Mukesh (2003) discussed the isopach mapping technique,
using electrical resistivity method and the depth of bedrock,
thickness of saturated zone, and bedrock resistivity drop
ratio in Luni block, Jodhpur district of Rajasthan. |
