Seasonal impact on water quality and model development of a tropical urban river / Siti Asiah Muhammad

Siti Asiah , Muhammad (2017) Seasonal impact on water quality and model development of a tropical urban river / Siti Asiah Muhammad. Masters thesis, University of Malaya.

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Abstract

Seasonal climatic variations in Malaysia may contribute to inadequate water supply, unexpected flooding, and river pollution issues.The Penchala River Basin located in Petaling Jaya, Selangor, Malaysia, is noted as being under environmental stress due to several pollution sources, which has amplified the intention to assess the water quality. Therefore, this research aims to study the seasonal impact on water quality and to develop a river model. Four stations from upstream toward downstream were selected along the Penchala River and was monitored from November 2013 until October 2014 on monthly basis. The chemical parameters were analyzed in laboratory guided by the Standard Method. The water quality index (WQI) was calculated using the 6 parameters, namely the Biochemical Oxygen Demand, Chemical Oxygen Demand, Ammoniacal Nitrogen, Total Suspended Solid, Dissolved Oxygen and pH. The result showed physico-chemical parameters have a significant difference between sampling stations (ANOVA, P<0.05) except for pH, turbidity and velocity. WQI classifies Penchala River in Class II (clean) for upstream, Class III (slightly polluted) for middle stream and class IV (polluted) for downstream. The WQI shows better values during wet season compared to dry season by increasing the WQI class from Class IV to Class III at Station 4 during wet season and dragged the WQI class from Class III to Class IV at Station 3 during the dry season. Heavy metals which elements exceeded the limits are Arsenic, Iron and Aluminium. The three elements that have a significant difference between the stations are Manganese, Magnesium and Iron (ANOVA, P<0.05). The heavy metals value during wet season show good value compared to dry season whereby the Arsenic values exceed the limit at Station 2 to 4 during wet season compared to the whole Penchala River during dry season. Model development used the InfoWorks River Simulation for hydraulic and water quality river model. The calibration and verification of flow at Kg. Ghandi and Jalan 222 showed a good agreement with the R2 values greater than 0.85 whereas, the calibration and verification stage showed a very good agreement at Kg.Ghandi but very poor agreement at Jalan 222. For water quality model, the BOD calibration showed an excellent agreement while DO and pH showed a very good agreement at middle and downstream of the Penchala River. In conclusion, Penchala River can be considered as having clean water at upstream, slightly polluted water at middle stream and polluted water at downstream. Seasonal variations contribute significantly on water quality and metal contamination at the downstream of the river.

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