Coastal groundwater salinization due to saltwater intrusion – new insights from a preliminary in-situ assessment

International Aquatic Research

دوره 15، شماره 1، خرداد 2023، صفحه 65-74   

نوع مقاله: Short communication

شناسه دیجیتال (DOI): 10.22034/iar.2023.1963612.1304

نویسندگان

Thomas D Kishore¹؛ Alvin Lal^{* 2}

¹Discipline of Civil Engineering, School of Information Technology, Engineering, Mathematics & Physics, University of the South Pacific, Suva, Fiji

²Global Centre for Environmental Remediation (GCER), College of Engineering, Science and Environment, The University of Newcastle, Callaghan, NSW 2308, Australia; crcCARE, The University of Newcastle, Callaghan, NSW 2308, Australia

چکیده

Access to clean water is a major problem for many countries including low-lying volcanic Island nations. Many of these volcanic Island nations are therefore heavily dependent on groundwater resources for their freshwater supplies. Saltwater intrusion compounded by rising sea levels, excessive abstraction, and anthropogenic activities often contaminates limited fresh groundwater resources. For the first time, available coastal groundwater salinity data obtained from an in-situ assessment is used to determine groundwater salinity levels in a low-lying volcanic atoll in Aitutaki, a major urban centre in the Cook Islands. The study examines groundwater quality data obtained during three different periods i.e., at the end of the rainy season in 1996, at the end of the dry season in 2015, and at the end of the rainy season in 2018. Also, groundwater salinity levels at different depths of monitoring wells were analysed to establish a groundwater salinity-depth trend. The results suggest that climatic conditions play a crucial role in the variation of the groundwater salinity levels in aquifers. It is observed that at the end of the dry season, the salinity levels are higher at lower aquifer depths. However, at the end of the rainy season, salinity levels increase with increasing depth. In addition, the study also reveals that the location of the groundwater pumping wells has a direct correlation with groundwater salinity levels. Groundwater pumping wells closer to the shoreline were observed to have high salt concentrations when compared to those sampling points that were further inland. Overall, the key findings suggest that groundwater salinity levels in the Aitutaki aquifer are increasing and there is an urgent need for saltwater intrusion protection and management interventions.

کلیدواژه‌ها

Low-lying volcanic Islands؛ Saltwater intrusion, Coastal aquifers, Coastal groundwater quality, Climate change