Investigating Effect of Pumping Ratio on Effectiveness of Barrier Wells for Saltwater Intrusion: Lab-Scale Experiments and Numerical Modeling

Shinichi Ozaki,Tatsuya Nagino,Christel Abi Akl,Yoshinari Hiroshiro

doi:10.3390/w13152100

Abstract

Saltwater intrusion, leading to the salinization of fresh groundwater, is the most challenging problem in coastal regions. Saltwater pumping from a barrier well is widely applied to prevent saltwater intrusion. Owing to its easy installation, many studies have investigated saltwater pumping. However, quantitative relationships between the barrier and inland production wells have not been revealed. In this study, lab-scale experiments were conducted to examine the effectiveness of a barrier well on the possible flow rate of freshwater from a production well. Moreover, a two-dimensional numerical model was created and simulated under the same conditions as those used in the experiments to analyze the experimental results. Consequently, a critical pumping ratio of 1.9 was obtained. In the numerical simulation, it was confirmed that an upconing of highly concentrated saltwater toward the barrier well was observed when the pumping ratio was less than the critical ratio. In conclusion, there is a critical pumping ratio between the barrier and the production well, and saltwater intrusion can be controlled by keeping the pumping rates under the critical ratio. Although further studies have yet to be conducted on a practical scale, this study showed the potential of the pumping ratio control to manage saltwater intrusion.

Highlights

The experiments showed that a barrier well can restore an aquifer to the previous state, despite the salinization at the production well, as compared in Steps 2 and 4
To analyze the experimental results, a numerical model based on the groundwater flow equation and pumping ratio between them was 1.9 under the experimental conditions
To analyze the experimental results, a numerical model based on the groundwater flow equation and solute transport equation was created and simulated under the same conditions as the experiments

Summary

Introduction

Saltwater intrusion is the lateral encroachment of seawater toward the coastal aquifer, leading to the salinization of groundwater and reduction in available freshwater sources. It is the most challenging problem in coastal regions. Saltwater intrusion is known to contaminate significantly large areas, spanning several kilometers in some cases [1]. According to Sherif et al [2], seawater intrusion has reached more than 100 km away from the coast in the Nile Delta aquifer, Egypt, even though it is perhaps the only case that seawater has intruded more than 100 km. The area requires long-term management to be restored to its initial condition [3]. Ebeling et al [4] showed that it can take as long as decades or centuries to remediate saltwater intrusion even with a mixed hydraulic barrier

Methods

Results

Conclusion