Confined aquifer dewatering optimization with a modified simulation–optimization method capable of determining the optimal well screen length and depth

Abstract

Simulation-optimization methods are widely used in dewatering optimization. However, traditional simulation–optimization methods do not address the optimization of well screen length and depth. This study proposes a modified simulation–optimization method for confined aquifer dewatering optimization, which is capable of determining the optimal screen length and depth. The proposed method is based on the linear programming method, and the multivariate adaptive regression splines method is also introduced to develop the prediction model for the parameters required in the linear programming model. A hypothetical case of deep excavation dewatering was optimized using the proposed method to demonstrate its feasibility, with the optimal pumping rate, screen length and depth of each well computed. Furthermore, parametric studies were performed to investigate the effects of some key factors on the optimization results, such as the number of considered pumping wells, required drawdown, insertion ratio of the waterproof curtain, aquifer anisotropy coefficient, and prescribed well screen. The results show that optimal total pumping rate and screen length generally increase with increasing required drawdown and aquifer anisotropy coefficient, while they decrease with increasing well number and insertion ratio of the waterproof curtain. Adjusting screen length is more critical to the optimization results since lower screen depth is always preferred. Optimizing well screen is more essential for higher well number, insertion ratio of the waterproof curtain, and lower aquifer anisotropy coefficient.