BACTERIAL MODELLING OF A RURAL TROPICAL STREAM USING THE QUAL2K MODEL

Abstract

Previous studies showed that the Serin River and its tributaries water and sediment were contaminated with Escherichia coli (E. coli) due to human activities along the river. Since the water of this river is important as a source of drinking water, body contact recreation, laundry and fsh culture, it is important that E. coli count be kept at a safe level for the health of the communities. Therefore, the objective of this study is to utilize the water quality model to simulate E. coli concentration in the river water for its designated use. The QUAL2K model was calibrated and validated using feld data from October 2009 to March 2010. The results showed that 80% of the predicted concentrations fall in the range of the observed values. Subsequently, the model was applied to simulate two different scenarios of designated use. The model simulation results showed that for the river water to be suitable as drinking water, no E. coli should be discharged from the headwater and from Bukah tributary. As for the suitability of the river water for recreational purposes, the maximum allowable concentrations of E. coli for the headwater, and the following tributaries, namely, the Bukah River, Pam River and Bukar River were 400 CFU/100mL, 900 CFU/100mL, 1000 CFU/100mL and 380 CFU/100mL respectively during low water level. During high water level, the maximum allowable concentrations from those tributaries are higher than that during low level due to increased dilution.