Specific Capacity of Wells in Some Hard Rocks of Karnataka

Specific capacities of forty wells from the hard rocks of Karnataka-granites (19 to 103 Ipm/m drawdown) ; basalts (13 to 199 Ipm/m drawdown); Bhima limestones (12 to 180 Ipm/m drawdown); laterites overlying basalts (3 to 223 Ipm/m drawndown); Bhima shales (9 to 55 Ipm/m drawdown) and chlorite schists (29 to 135 Ipm/m drawdown) have been determined. The yield of wells in general ranges from 35 to 199 klpd from these tested wells. It is found that in general (i) specific capacity increases with an increase in cross-sectional area of the wells and (ii) specific capacity decreases with increase in recovery time.