A New Approach for Detection of Hidden Aquifer Using DC Resistivity Data Transforms

Direct current resistivity is most commonly used as a potential tool in finding new resources of groundwater This task is achieved by conducting Schlumberger and Wenner resistivity soundings Usually, no signatures of the presence of a conducting layer/aquifer sandwiched between two resistive layers in hard rock regions are observed in apparent resistivity curves In such a difficult situation, detection of hidden aquifer employing one dimensional conventional approach of interpretation becomes a tedious job A new non conventional method based on apparent resistivity data transforms is attempted to overcome these difficulties Assummg as many layers as the number of observations, and apparent resistivities as true resistivities, ratio of transverse resistance of the layer to total transverse resistance of all overlying layers (QOT) and ratio of longitudinal conductance of the layer to total longitudinal conductance of overlying layers (QLC) are computed The plots of QLC and QOT against half current electrode spacing on bilogarithmic graph show sharp contrast at interfaces of layers As a result, useful information about thicknesses of layers is extracted from these curves for inversiOn of observed data The efficiency of this approach is tested on synthetic data and finaally it is applied on fleld data to delineate hidden aquifer and to enhance the resolution of model parameters in interpretatiOn This approach is found very useful to Identify the hidden aquifer when no a priori informatIOn IS available.