RWH Unit depth design process bedrock Purpose methods presence thickness importance Electrodes Objectives soil layers Applications straight line storage tanks aquifer zones critical tool common method VES) technique brief overview recharge wells Identification essential data allegianceindia various contexts optimal locations Geophysical survey water infiltration effective locations subsurface conditions Allegiance Enterprise electrical resistivity deeper subsurface layers Resistivity Measurements Schlumberger Configuration Allegiance Water Management rainwater harvesting systems Vertical Electrical Sounding groundwater quality variations rainwater harvesting structures