Abstract
Groun in a very complex way. In this work, multivariate statistical analysis was used to evaluate the factors controlling the groundwater chemistry of Kapas Island (Malaysia). Principal component analysis (P dwater chemistry of small tropical islands is influenced by many factors, such as recharge, weathering and seawater intrusion, among others, which interact with each other CA) was applied to 17 hydrochemical parameters from 108 groundwater samples obtained from 18 sampling sites. PCA extracted four PCs, namely seawater intrusion, redox reaction, anthropogenic pollution and weather factors, which collectively were responsible for more than 87% of the total variance of the island’s hydrochemistry. The cluster analysis indicated that three factors (weather, redox reaction and seawater intrusion) controlled the hydrochemistry of the area, and the variables were allocated to three groups based on similarity. A Piper diagram classified the island’s water types into Ca-HCO3 water type, Na-HCO3 water type, Na-SO4-Cl water type and Na-Cl water type, indicating recharge, mixed, weathering and leached from sewage and seawater intrusion, respectively. This work will provide policy makers and land managers with knowledge of the precise water quality problems affecting the island and can also serve as a guide for hydrochemistry assessments of other islands that share similar characteristics with the island in question.
Highlights
Groundwater is becoming the main source of freshwater for domestic, agricultural and other human activities in many places, in coastal areas [1] where rapid population growth and intensive economic activities are pushing the demand for fresh water to its limits [2]
Physical and chemical parameters of Kapas Island were successfully analyzed with Principal component analysis (PCA) and hierarchical cluster analysis (HCA)
PCA results suggest that the first component is the highest and the most influential factor regarding the chemistry of the groundwater, and it involves multiple processes, the dominant of which is seawater intrusion
Summary
Groundwater is becoming the main source of freshwater for domestic, agricultural and other human activities in many places, in coastal areas [1] where rapid population growth and intensive economic activities are pushing the demand for fresh water to its limits [2] This is even more severe in small tropical islands such as Manukan Island (Malaysia) where groundwater has no substitute in providing fresh water [3], despite the high amounts of annual rainfall (more than 2,000 mm) such islands receive, especially during monsoon season [4]. Effective pollution control and sustainable water resources management are necessary to tackle such challenges of water quality [9] These require a lot of research work that can provide an in-depth understanding of the current quality situation and of any factors influencing the groundwater chemistry [10], which is sadly lacking [11]; very little is known about the hydrochemistry status of groundwater in small tropical islands [5]. To effectively and properly protect groundwater, it is crucial to be able to evaluate the factors influencing the groundwater chemistry and translate this information (which is currently lacking) into a reliable and sustainable water management strategy that will guide end-users, such as land and water-resources managers, to prevent or minimize harmful impacts on groundwater quality and to ensure sustainability of fresh water resources for both human use and ecosystems in general
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