Risk quotient analysis and total maximum daily load estimation for Kedah River, Malaysia

Abstract

Kedah River plays an important role in providing habitat for aquatic plants, animals, and it has been widely used by humans for recreation purposes. However, rapid development and urbanization activities along the river have significantly impacted the surface water quality in the watershed. Nowadays, Total Maximum Daily Load (TMDL) is one of the best approaches for restoring an impaired watershed. TMDL is used to identify the maximum concentration of pollutants that a waterbody can receive without violating the water quality standards. This study was intended to conduct a TMDL assessment for five water quality parameters which are turbidity, suspended solids (SS), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and Ammoniacal Nitrogen (NH3N). The calculation includes identifying the existing load, target pollutant load, and the endurance capacity of load using secondary data adopted from DOE. Risk Quotients (RQs) analysis was included in this TMDL study to address the water health systematically. From the result, most of the existing pollutant from year 2013 to 2017 exceeded the standard value of Class IIA by NWQS especially for SS, BOD, and NH3N.