TITLE:
Identification of Groundwater in Hard Rock Terrain Using 2D Electrical Resistivity Tomography Imaging Technique: Securing Water Scarcity at the Time of Seasonal Rainfall Failure, South Andaman
AUTHORS:
Maniruzzaman Sk, N. Ramanujam, Vysakh Champoil, Swapan Kumar Biswas, Qazi Akhter Rasool, Chandrakanta Ojha
KEYWORDS:
Aquifer, 2D Electrical Resistivity, Wenner-Schlumberger Array, Ground Water, South Andaman, Ophiolite
JOURNAL NAME:
International Journal of Geosciences,
Vol.9 No.1,
January
29,
2018
ABSTRACT:
Like many of the tropical islands, the population of Andaman and Nicobar
Islands, though not directly, relies predominantly upon rain water harvesting
to quench their need and also depends on the groundwater sources. In the
background of climate change, severity of hydrological cycle is much anticipated
which may cause more extreme and unusual precipitation. It is quite essential to
have other alternatives. Accordingly, groundwater could be exploited as a potential
alternative. The present study intends to find out the potential groundwater
source and estimate aquifer parameters in Kodiyaghat (KD) and Burmanallah
(BN). As these areas are composed of very hard rock, Wenner-Schlumberger
array has been used to carry out a 2D Electrical Resistivity Tomography survey
to find out the fracture zone as well as to delineate the aquifer. KD and BN
show maximum resistivity of 25,416 Ωm and 5985 Ωm indicate very hard
rock terrain. Similarly, the minimum values of resistivity (21.6 Ωm and 30.4
Ωm) were observed at KD and BN define the presence of freshwater aquifers
respectively. The aquifer identified was found to be at a depth of 5 m to 19.9
m at KD and 2.5 m to 20 m at BN. The calculated Hydraulic conductivity
(14.85 m/day and 30.14 m/day), transmissivity (86.25 m2/day and 271.27
m2/day) and porosity (28.7% and 31.24%) values at KD and BN confirmed
that, the located aquifer was of fresh ground water quality and can be utilized
for drinking and house hold purposes. According to the results, almost 70% of
the study area is hard rock terrain and 30% comes under potential aquifer
zone. The results also show that, both the areas were characterized by Horst and Graben topography and suggest possible groundwater sources for future
exploration.