ANALYSIS OF TEST, PUMPING DATA FOR UNCONFINED AQUIFERS

Abstract

Hydraulic characteristics of aquifers are essential to the understanding and solution of aquifer problems and the proper utilization of ground water resources. For a reliable determination of these parameters the necessary data is obtained through field tests. Analysis of systematic observation of water level changes and of other test data yield values of the aquifer characteristics. The reliability of these analyses are dependent on several factors amongst the importants, one is the method of analysis. The most widely used method of analysis has been that of type curves which has certain limitations and also inherent subjective bias. To include the effect of delayed yield (the slow drain-ing behaviour of unconfined aquifers) as well as the effect of partial penetration which is the most encountered case in prac-tice, because of the large number of dimensionless parameters which wi-'l come up in the drawdown expression, it would be 0 impossible are at least greatelydifficult to prepare a set of type curves for the entire range of field application. In the present work, based on one of the powerful theories of unconfined aquifers, a computer routine is prepared. For the calculation of aquifer parameters a non linear optimization scheme is proposed. The proposed scheme calculates the optimal values of the aquifer parameters based on the minimization of the sum of squares of the differences between the observed and calculated drawdowns.