The Application of Total Maximum Daily Load (TMDL) Approach in Water Quality Assessment for The Batu Pahat River

An increased number of rivers categorized as polluted is alarming that their repercussions are so severe that the rivers can no longer be rehabilitated. This pollution might result from rapid urbanization and population growth, uncontrolled development, which produces a high volume of water pollution that is discharged into the river. Rapid development has led to a large discharge of point source (PS) and nonpoint source (NPS) pollution into the water supply. As a result, the deterioration in water quality, a decline of safe water supply, and the difficulties in accessing clean water have emerged as massive concerns for water authorities attempting to fulfill the increasing supply of clean water resources. To resolve these issues, several approaches were implemented to determine the best approach that could effectively control water quality pollution in Malaysia. One of the best methods that could be used to manage the water quality is Total Maximum Daily Load (TMDL). TMDL seeks to establish or restrict the amounts of a pollutant allowed to enter the river and is assisted by identifying physical, chemical, and organic qualities in the river water body. In this study, six parameters were measured such as dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammoniacal nitrogen (NH^3-N), total suspended solids (TSS), and pH. QUAL2K software was utilized to model the water quality and test several scenarios to reduce the pollutant concentration. The analysis shows that the commercial sector poses the most contributor to the pollution loading (kg/day) in Batu Pahat River, mainly from workshop, wet market and restaurant. In addition, low tide flow produced a higher pollution load (kg/day) than high tide flow due to larger discharge during high flow. In conclusion, the development TMDL plan could improve water quality at the Batu Pahat River by analysing pollution loading reduction and future management of watersheds area.