Modeling approach to evaluation of environmental impacts on river water quality: A case study with Galing River, Kuantan, Pahang, Malaysia

One of the major issues in Kuantan, Pahang, Malaysia is the water quality of Galing River which is flowing through the area. Currently, overall water quality of the river is very poor, i.e., Class IV (based on the Malaysian water quality standards), mainly due to wastewater discharged from residential area and industries without being properly treated. Due to severe pollution, aquatic ecosystem has not been properly developed. Thus, it is being considered to construct a new wastewater treatment plant (WWTP) to prevent discharge of pollutants and to improve the river water quality. Therefore, this study was conducted to identify the pollution sources along the river and assess their impacts on the water quality. In addition, a numerical model was formulated with the Environmental Fluid Dynamic Code (EFDC) to find a best plan to improve the water quality. Through the model simulation, it was found that wastewater from all the U-drains and culverts along the river should be collected by sewer, transported to a WWTP for treatment, and then pumped to the upstream of the river for discharge. It was also found that if the WWTP would reduce pollution load by 80%, the current water quality of the river would improve by 80% to achieve Class II.