Water Quality Evaluation at the Tinanan-Kulaman River Confluence: A Multi-Site Physicochemical Assessment

This study evaluated the physicochemical water quality parameters at four sampling sites along the confluence of the Tinanan and Kulaman Rivers in Arakan, Cotabato, Philippines. The parameters assessed included temperature, electrical conductivity (EC), total dissolved solids (TDS), pH, and salinity. Sampling was conducted on May 30, 2026 at the following sites: Site 1 (50 m upstream of the confluence along the Tinanan River), Site 2 (at the confluence), Site 3 (50 m upstream of the confluence along the Kulaman River), and Site 4 (50 m downstream of the confluence). Three replicate measurements were collected per site using a calibrated pH meter capable of measuring multiple physicochemical parameters. Mean ± standard deviation values were computed and compared using one-way ANOVA. Results revealed that all physicochemical parameters were within the acceptable limits set by the Department of Environment and Natural Resources (DENR) Administrative Order 2016-08. No significant variation in salinity was observed across all sites. However, notable differences were detected in EC and TDS between the Tinanan River site and the Kulaman River site, reflecting the distinct hydrological characteristics of each tributary. The confluence zone exhibited intermediate parameter values, suggesting mixing effects. The findings indicate that both rivers maintain good water quality at the point of confluence, providing baseline data for future long-term monitoring and watershed management.

water quality, physicochemical parameters, river confluence, Tinanan River, Kulaman River, TDS, EC, pH, salinity, DENR DAO 2016-08

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