Performing application of cooper-jacob method for identification of storativity

Abstract

Transmissivity is estimated by fitting a straight line between time versus drawdown on semi-logarithmic paper. The test data of both confined and unconfined aquifers were analyzed by many practitioners that are used cooper-Jacob method to estimate the drawdown equation, regardless of the differences between theoretical and practical conditions. The other parameter is storativity overestimated, so the aim of this research is to analyze ten pumping test data located in Makassar area by using cooper-Jacob’s (1946) time drawdown approximation of Theis method to estimate the aquifer parameters, also in order to determine the reasons which are affecting the reliability of the storativity value and obtain the important aspect behind that in practice. The pump well is installed to a depth of 20 m, the end is 2 meters into the hard consistency clay layer. The radius of the pump well used in a single well test to estimate the storativity value of the type of aquifer layer unconfined with the Cooper-Jacob method gives excessive value, but if the radius of the pump well is used larger by inserting the radius of the gravel filter layer is obtained a significant value that approaches the storativity value that has been estimated by Theis method uses one pump well and nine observation wells.