Conceptualizing seawater intrusion processes in small tropical island via geochemical modelling

Abstract

Geochemical modelling approach has been applied to demonstrate seawater intrusion phenomena in a coastal aquifer of Manukan Island, Sabah. Geochemical modeling output using PHREEQC showed that the migration of seawater into the fresher parts of the aquifer has resulted to a calcification of the aquifer. The chemical compositions of near coast zone and further landward area have a significant effect on the processes during the intrusion. Moreover, previous numerical modeling output showed upconing process leads to the migration of seawater and the possible route of seawater to influence the groundwater chemistry. Results of geochemical modeling output are the basis for future groundwater management strategies and protection in Manukan Island. SWOT analysis output has highlighted the strengths, weakness, opportunities and threats to facilitate assist in the management of environmental as well as groundwater of Manukan Island. The output of this study has also provided a foundation, which can be used in other small islands of similar hydrogeological condition to illustrate seawater intrusion using geochemical modeling approach.