Assessing the protective effect of cutoff walls on groundwater pumping against saltwater upconing in coastal aquifers. (1st December 2022)

• Record Type: Journal Article
• Authors: Abdoulhalik, Antoifi; Abdelgawad, Abdelrahman M.; Ahmed, Ashraf A.; Moutari, Salissou; Hamill, G.
• Is Part Of: Journal of environmental management. Volume 323(2022)
• Publication Date: 2022-12-01
• Subjects: Seawater intrusion -- Subsurface barriers -- Groundwater abstraction -- Coastal aquifer management -- Saltwater upconing -- Pumping well salinisation -- Laboratory experiments -- Numerical modelling; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2022.116200
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Subsurface physical barriers are amongst the most effective methods to mitigate seawater intrusion in coastal aquifers. The main objective of this study was to examine the impact of cutoff walls on saltwater upconing using laboratory and numerical modelling experiments. Physical experiments were first completed to reproduce the saltwater upconing process in a laboratory-scale coastal aquifer model incorporating an impermeable cutoff wall. Numerical modelling was used for validation purposes and to perform additional simulations to explore the protective effect of cutoff walls against saltwater upconing. The results suggest that the cutoff wall did not substantially delay the saltwater upconing mechanism in the investigated configurations. Laboratory and numerical observations showed the existence of some residual saline water, which remained on the upper part of the aquifer on the seaward side of the wall following the retreat of the saltwater. The protective effect of cutoff walls was noticeably sensitive to the design parameters. Specifically, cutoff walls installed close to the pumping well enabled the implementation of higher pumping rates, therefore a more optimal use of the freshwater, especially for deeper wells. The results highlighted that the penetration depth of the cutoff walls may not necessarily need to exceed the depth of the pumping well to ensure effectiveness, which is of great importance from construction and economic perspectives. Highlights: The influence of subsurface barrier on saltwater upconing mechanism was examined. The cutoff wall did not substantially delay the occurrence of the upconing process. Walls closer to the well and deeper induced higher percentage increase values. The wall depth need not exceed the depth of the well to ensure good protection.