Simple approximation of well function for constant drawdown variable discharge artesian wells

A simple approximation of the well function for a constant drawdown is developed. This approximation is used to estimate the storage coefficient and transmissivity of the aquifer from observed unsteady discharge under a constant drawdown condition, using an optimization method. Another simple approximation for calculating the total production volume during a time span is also developed. The developed approximations for the well function and production function are accurate within a maximum error of 0.7% for the practical range of the argument.