OPTP is a simple, user-interactive DOS program for computing the optimal discharge of a well in terms of benefit (of water produced) versus pumping cost, using a single-variable (i.e., discharge) constrained nonlinear programming algorithm. Required variables include pump efficiency, cost of energy to pump [$/kwh], static lift required [m or ft], and value of water produced [$/cu.m or $/gpm]. The coefficients C1, C2 and exponent P of the objective function are to be determined from a step-drawdown pumping test. The program calculates the optimum range of discharge rates for given accuracy, the related values of the objective function, the actual accuracy, and the resulting drawdown. The calculated drawdown is checked against a user-specified maximum drawdown.

The OPTP package includes the program PTEST which computes the coefficients C1 and C2 and the coefficient P of the non-linear drawdown equation s = C1.Q + C2.Q^P (Rorabaugh, 1953) using three-step data from a step-drawdown pumping test. In this equation, the term C1.Q represents the aquifer head loss component of the drawdown, and the term C2.Q^P the well loss component. Q is the discharge rate. To solve for the coefficients in this equation it is assumed that the well is pumped intermittently at different discharge rates, and that the water table is allowed to recover fully at the end of each pumping step.

OPTP is a public domain program which sends non-graphical output to both the screen and to an ASCII text file. The program runs as a DOS application under MS Windows. Distribution includes source code, runtime versions, and example output files.

SYSTEM REQUIREMENTS

Intel 80i86 based computer with math coprocessor, 256 Kb free RAM, DOS 2.1 or higher.

Authors: G.N. Paudyal and A. Das Gupta (Asian Institute of Technology).