Analysing the Combined Effect of Barrier Wall and Freshwater Injection Countermeasures on Controlling Saltwater Intrusion in Unconfined Coastal Aquifer Systems
- 100 Downloads
Freshwater recharge wells and underground flow barriers are among several methods proposed for controlling saltwater intrusion (SWI) into coastal aquifers. In this study, experimental and numerical studies were performed to determine the effect of using a flow barrier wall, a recharge well and a combination of these, to control SWI in unconfined coastal aquifer systems. The SEAWAT model was used to predict the SWI wedge and the behaviour of the retreating residual saltwater after installing the remediation measures. The results show that increasing the barrier wall embedment ratio (db/d) from 0.44 to 0.67 led to an increase in the repulsion ratio (R) from 20.8 to 46.87%. Moreover, increasing the freshwater injection rate ratio (Qi/Q) from 0.22 to 0.56 increased the repulsion ratio (R) from 10.93 to 22.39%. Barrier wall embedment with ratios (db/d) of 0.44, 0.51 and 0.57, combined with a freshwater injection ratio (Qi/Q) with a value of 0.56, achieved (R) of 41.14, 45.41 and 50.0%, compared with 20.8, 27.1 and 34.40% for the barrier wall only and 22.39% for freshwater injection only. Freshwater injection ratios (Qi/Q) of 0.22, 0.33, 0.44 and 0.56 combined with a barrier wall embedment ratio (db/d) of 0.508 achieved repulsion ratios (R) of 33.9, 36.5, 39.0 and 45.42%, compared with 10.9, 15.6, 18.8 and 22.4% respectively for freshwater injection only and 27.1% for the barrier wall only. A combination of flow barrier and freshwater injection forced the saltwater to retreat and achieved values of R greater than either the barrier wall or freshwater injection separately.
KeywordsSaltwater intrusion Freshwater injection Barrier wall Combination
The first author would like to thank Prof Jiro Takemura in helping to fabricate the sand box model in Tokyo Institute of Technology, Japan.
Compliance with Ethical Standards
Conflict of Interest
- Attanayake P, Sholley M (2007) Evaluation of the hydraulic gradient at an island for low-level nuclear waste disposal. IAHS Publ 312:237–243Google Scholar
- Bear J (1979) Hydraulics of groundwater. McGraw- Hill Book Co., Inc., New YorkGoogle Scholar
- Bruington AE, Seares FD (1965) Operating a seawater barrier project. J Irrig Drain Eng 91(1):117–140Google Scholar
- Guo W, Langevin CD (2002) User’s guide to SEAWAT: a computer program for simulation of three-dimensional variable-density ground-water flow. U.S. Geol. Surv., RestonGoogle Scholar
- Hasan Basri M (2001) Two new methods for optimal design of subsurface barrier to control seawater intrusion. PhD Thesis. The Univ. of ManitobaGoogle Scholar
- IPCC (2013) Summary for policymakers. In: Climate change 2013: the physical science basis. Contribution of working group I to the fifth assessment report of the intergovernmental panel on climate change. IpccGoogle Scholar
- Luyun RA (2010) Effects of subsurface physical barrier and artificial recharge on seawater intrusion in coastal aquifers. PhD thesis. Kagoshima University, JapanGoogle Scholar
- USEPA (2017) Report to congress: class V UIC study fact sheet - aquifer recharge Wells and aquifer storage and recovery Wells, EPA/ 816-R-99-014t. Office of Groundwater and Drinking Water, Washington, DCGoogle Scholar