Exploring deep potential aquifer in water scarce hard rock terrain
Introduction
Water scarcity is a well known problem in world particularly in the hard rock terrain of arid and semiarid Climatic condition, where groundwater level has considerably declined due to over-exploitation and atypical rainfall. Bore-wells upto 60 to 70 m deep are not yielding enough water to fulfill the requirement. The underground reservoirs are expected to dry by few decades in many regions, if the present level of exploitation and excess use of underground water continues. Even though, the groundwater is replenishable due to rainfall, the disturbance between recharge and Pumping is widening due to increasing population accompanied by agriculture and industrial development. The groundwater in the hard rock region can be occurred into two distinct systems i.e. shallow depth aquifer and deep aquifer. The shallow depth aquifer is more vulnerable to both scarcity and contamination when compared with deep aquifers.
Few decades back, deepness to groundwater was very shallow, and exists in the weathered or laminated portion of the hard rock areas. However, due to the waxing stress on the groundwater system, water levels declined to the deep seated fractured zone. Even the deeper wells also turns dry due to confined potential of fracture system and extensive development. The fissured/fractured zone connected with lineament still has better chances of supplying the water. As density of fracture decreases with depth, exploration of deep fractures becomes a strenuous task. Groundwater in crystalline rocks such as granites, gneisses and schists are mainly restricted to Weathered and fracture zones. In response of heterogeneity in the hard rock, especially in t...
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... the field. Invert the acquired data by RES2DINV inversion program (This program use to alter and represent field data of electrical geophysical prospecting of electrical resistivity and induced polarization). Inverted resitivity images arrange as per their layout and interpret result. As the high electrolytic conduction is mainly responsible for current flow in granite, the low resistivity is an indication of weaker, i.e., weathered-fractured zone saturated with water. Such thick and deep anomalous zone is considered as an indication of deep tectonic fractures saturated with water.
To validate the result, drill a well at recommended site down to a recommended depth. If fractured zone is encountered with ingress of water, install a motor to exploit the water. Further validation may be carried out by hydrochemical analysis and synthetic 2D resistivity modeling.