Would Mixed Physical Barriers be able to Desalinate Coastal Aquifers from Seawater Intrusion Under Pumping Conditions?

Abstract

This study used the SEAWAT model to investigate the potential of using mixed physical barriers (MPB) to control SWI under pumping conditions in typical homogenous and layered heterogeneous coastal aquifers. The numerical models were based on controlled two-dimensional (2D) laboratory tests and field studies in the Biscayne aquifer, which is situated in the Cutler Ridge region close to Deering Estate, Florida, USA. The modelling results revealed critical insights into SWI behaviour under pumping conditions. Specifically, it was observed that the intrusion wedge extended significantly further inland in layered heterogeneous aquifers and homogeneous aquifers compared with the base case without pumping. Results showed that coastal aquifers with bottom low-hydraulic conductivity have smaller SWI compared with top and middle-layered aquifers. The SWI repulsion reached +27% by installing the MPB, while the groundwater salinity increased to +25%, -0.30% and -60% by increasing the abstraction well rates by 10 m3/day, 15 m3/day and 20 m3/day, compared with no pumping at the baseline case and MPB. The current study results are very interesting for coastal aquifer management and require economic study to ensure the feasibility of using this method.