Determination of aquifer characteristics of semi-confined aquifers from single well tests

This paper describes a method to determine all the aquifer characteristics of semi-confined aquifers from data of single well tests only. They are always more abundant than aquifer tests with observation wells required at present. The method requires a semi-log time-drawdown or time-recovery data plot of a constant rate pumping lest corrected for the well loss derived from a step-drawdown test. First the transmissivity (KD) of the aquifer is determined by the Jacob method. Then the product of aquifer storativity and the vertical resistance of the aquitard (SC) is determined by matching the data plot with a calculated time-drawdown plot of the transmissivity of the aquifer and the product of any assumed value of SC. The steady state drawdown of the data plot yields the values of the De Glee function Ko(r/L) and r/L from which the product of the transmissivity and the vertical resistance KDC can be determined. With above parameter combinations the transmissivity and storativity of the aquifer and the vertical resistance of the aquitard can be determined separately. Application of the method to single well test data without well loss correction and the application of Walton's type curve method are examined.