Sediment Transport and Water Quality Analyses of Naic River, Cavite, Philippines

The study aimed to investigate the relationship between sediment transport and water quality change in Naic River, Cavite — a body of water exposed to various environmental and anthropogenic stressors such as urbanization, pollution and flooding. This research seeks to contribute to the limited research-based understanding of the dynamic, and potentially harmful relationship between sediments and water quality. To fill the gap, this study utilized the Hydrologic Engineering Centre-River Analysis System (HEC-RAS) model to forecast the river’s sediment volume and water quality from the period of January 2020-2021 using average weather flow under existing river geometry and characteristics. Additionally, water samples collected from three stations of the river were used for the analyses. This research has found that significan sediment volume will accumulate in the river, BOD will also increased, and the DO on the other hand decreased by the end of the year. Statistical analyses have also revealed a strong inverse relationship between the DO and the cumulative sediment volume; and a weak direct relationship between the cumulative sediment volume and the BOD. A potential increase in sediment volume will be particularly significant in the river's outlet based on the projection made which suggests that the Naic River might receive high amounts of pollutants. Furthermore, there was a strong agreement between the actual data and the HEC-RAS predicted data — which accounts for the efficiency of the method used in the study. Finally, because its water quality falls short of DENR's standards, this research confirms that the river is polluted. The results of this study may be used for close monitoring of the parameters that cause degradation of the water quality in the river. Various engineering solutions such as decentralized wastewater treatment and sustainable sediment management strategies are suggested to improve river water quality.