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.
Highlights
Aquifers in fractured rocks are generally considered of minor importance compared to those in primary porous media, on which the attention has mainly been focused up until now
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
The purpose of this study is to explore the capabilities of the resistivity imaging method for the detection of fractures and/or fractured zones buried an overburden by using 2D imaging methods, and demonstrating case study examples from experiments in hard rock environments in Kodiyaghat and Burmanallah where to meet the rising incapable demand of water of the island and surrounding areas
Summary
Aquifers in fractured rocks are generally considered of minor importance compared to those in primary porous media, on which the attention has mainly been focused up until now. The amount of ground water available in fractures is generally limited, at least in arid and semi-arid regions. This type of aquifer is a primary source of water for man in vast area throughout the world, where aquifers with primary porosity are practically non-existent and surface waters are ephemeral [1]. In hard rock environments fractures and overflowing streamlines are the main indicators of groundwater [2]. Both vertical and lateral fractures in hard rock areas influence and determine groundwater infiltration and migration. The purpose of this study is to explore the capabilities of the resistivity imaging method for the detection of fractures and/or fractured zones buried an overburden by using 2D imaging methods, and demonstrating case study examples from experiments in hard rock environments in Kodiyaghat and Burmanallah where to meet the rising incapable demand of water of the island and surrounding areas
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