Effect of Seasonal Variations and Wastewater Point Sources on Water Quality in the Phetchaburi River

Abstract

The objective of this research was to investigate the effects of seasons on the water quality of the Phetchaburi River by analyzing the physical, chemical, and biological water quality. Water samples were collected from multiple locations along the Phetchaburi River, including agricultural areas, residential communities, fishing farms, and mining sites, resulting in a total of 39 sampling points. The study found that the rainy season and dry season significantly affected the electrical conductivity (EC), total suspended solids (SS), total dissolved solids (TDS), total solids (TS), pH, biochemical oxygen demand (BOD), ammonia (NH₃), Orthophosphate (PO₄^3-), salinity, Total Coliform bacteria (TCB), Fecal Coliform bacteria (FCB) and Escherichia coli. These effects were statistically significant at a 95% confidence level. The research identified fishing farms as the most significant source of water pollution. Additionally, areas with agricultural activities, residential communities, and mining sites showed high levels of nutrients, and bacterial contamination, especially during the dry season when dilution by higher water volumes in the Phetchaburi River was less effective.  The findings of this study are crucial for monitoring and verifying water quality to restore the quality that is not sea water of the Phetchaburi River's water and to sustainably maintain the river's ecosystem.