Pumping Tests in Patchy Aquifers

ABSTRACT A numerical simulation and analytical study of a constant‐rate pumping test, for a well situated at the centre of a disc of anomalous transmissivity and storage coefficient, have been used to aid in the interpretation of tests performed in a “patchy” aquifer in India. Equations describing the long‐time behaviour of drawdown show that Jacob's method can be employed to estimate the regional transmissivity from drawdowns measured at any point in the aquifer or in the pumping well. However, these equations also show that an average storage coefficient should be calculated from drawdowns measured outside the aquifer discontinuity. The results of this study support the hypothesis that the average transmissivity of a heterogeneous aquifer can be calculated from rates of drawdown observed after long periods of pumping.