Abstract
In determinating the producibility of a well, the s-Q curve obtained by step drawdown test can be approximated in many cases by the Jacob's empirical equation of s＝BQ＋CQ2, and there is no discontinuity in the curve.
Mathematical maximum curvature point in Jacob's empirical equation is given by 0.5126B/C when plotted on log-log graph, but it cannot be said to the critical pumping rate of a well.
In some cases, an obvious discontinuity appears on a s-Q curve that cannot be approximated by the Jacob's empirical equation. Some of these cases, it is common that high pervious unconfined aquifer is underlain by impervious formation and well screen is installed also in the impervious layer. This discontinuity indicates the limit of pumping rate of a well and varies with water table fluctuation.
