Groundwater Quality Variations during Wet and Dry Seasons in Agricultural and Forested Areas in the Philippines

The study analyzed the variations in groundwater quality in the Philippines. Groundwater samples were collected from wells and springs in agricultural and forested areas in the provinces of Ilocos Sur, Benguet, Nueva Ecija, Cebu, and Davao del Norte. Temperature, pH, DO, EC, and DOC were measured during the dry (March to May 2022) and wet (June to October 2022) seasons. Based on the MANOVA, there was an overall land use (Wilks’s λ = 0.00867, p < 0.001) and season (Wilks’s λ = 0.695, p < 0.005) effect on the groundwater quality. Nonetheless, there was no land use by season effect (Wilks’s λ = 0.947, p = 0.770) on the groundwater quality. These findings suggest that land use and season are crucial in shaping groundwater quality. PCA indicated that the cumulative variability of the components having eigenvalues ≥1.00 is 68.67%. Component 1 represents a positive association with all parameters except DO, while Component 2 represents a negative association with DOC. This study highlights the need for further research to establish the spatiotemporal variations in groundwater quality in several parts of the country. The study also recommends refining groundwater quality assessment and monitoring methods in the Philippines.