抄録
An efficient well is essential to arrange a pumping test for aquifer's hydraulic properties determination or for quick water withdrawal purpose. A step-drawdown pumping test is needed to determine the aquifer formation loss coefficient B_f, the entry loss coefficient C_f and the turbulence coefficient n through which well efficiency is determined using the Jacob's equation. As the relationship is non-linear, generally its solution is obtained by the graphic, simultaneous equations solving or one dimensional optimization methods. But all of these methods have some disadvantages. Therefore, the genetic algorithm (GA) is employed to estimate these parameters and thereafter to determine the efficiency of a tubewell located in Tangail district, Bangladesh. Results show that there is a good agreement between the simultaneous equations solving method and GA. Moreover, GA has minimum sum of square of errors value and sum of absolute deviations value with unique solution. But the results by the graphic method differ significantly from those by both of these methods. Therefore, GA could be considered as an efficient technique for Jacob's parameters estimation and well efficiency determination. An inverse methodology of well efficiency determination for same design capacity wells running in the same aquifer is also proposed.
