Groundwater Quality Dynamics in the Coastal Aquifer of Tipo-Tipo, Basilan, Philippines

Abstract

In coastal areas like Tipo-Tipo, Basilan, groundwater isn’t just a resource; it’s a daily necessity. Families rely on it for drinking, farming, cooking, and cleaning. But this lifeline is quietly being threatened by saltwater intrusion.  The study aims to assess the hydrochemical characteristics of groundwater in the coastal aquifer of Tipo-Tipo, Basilan, by measuring key physico-chemical parameters such as pH, electrical conductivity, salinity, total dissolved solids, and major ions, determine the possible saltwater intrusion and its impact on groundwater quality, and compare the quality based on the WHO and PNSDW standards. The groundwater samples were collected from existing wells during both high and low tides and tested for key indicators, including EC, pH, TDS, Temperature, Cl, SO4, TA, Ca, Mg, Na, K, CO3, and HCO3. The findings revealed clear changes in water quality between high and low tide. During low tide, the concentration of salt and minerals, such as chloride, sodium, and magnesium, increased noticeably, indicating that seawater was intruding into the freshwater supply. The shift in water composition, from magnesium–sulfate to magnesium–chloride, confirmed that saltwater was intruding into the inland; however, all results were within safe limits, based on WHO and PNSDW. This study provides relevant information that the coastal groundwater of Tipo-Tipo needs to be protected and managed more carefully.