Peri-urban water quality monitoring in the Sisa-Oda catchment of Kumasi

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The Sisa-Oda Catchrnent spans across the eastern part of Kumasi and comprises many rivers including Rivers Sisa, Subin and Weewee. It drains southwards thereby having extensive and intimate interactions with the city with debilitating effects. As a growing city with several socioeconomic and environmental challenges, the management of this resource seems quite a remote priority as it continues to be glaringly abused. The purpose of this study is to contribute towards its management through water quality assessment. The study involved discussions and observations of some industrial and communal activities, as well as water sampling from nine sites involving six rivers and two sampling regimes corresponding to the local weather — the dry and wet seasons. Water quality analysis involved physical, chemical, and biological parameters and the results were compared with EPA guidelines. There were also river flow measurements and comparison with other works. The results showed that pollution was highest near the city centre, especially River Subin at Asafo while areas near the outskirts were the least polluted, especially River Weewee at Ahinsan. Faecal coliform was the most severe pollutant as its pollution index generally varied by about 45000 to 3,000,000%, while nitrate was the least severe with about 0 to 2% pollution index. The volume of water flowing out of the catchment polluted was estimated at 5.2m3/s as against 1.0m3/s of treated water consumption for the whole the Kumasi Metropolis. Water treatment was more difficult for this catchment as the Odaso Water Works downstream consumed 130 bags of alum/day for a capacity of 2.5m gallons against 100 bags for Barekese Water Works elsewhere with a capacity of 18m gallons/day. Furthermore, river pollution was on the increase and innovative measures, such as public education and wastewater treatment systems were needed to address it.
A thesis submitted to the Department of Mineral Processing and Extractive Metallurgy, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the award Master of Science, 2002