Assessment of Seasonal Variation in Water Quality in River Rwizi Using Multivariate Statistical Techniques, Mbarara Municipality, Uganda

Abstract

Assessment of seasonal variations in surface water quality characteristics is an essential aspect for evaluating water pollution due to both natural and anthropogenic influences on water resources. In this study, temporal variations of water quality in river Rwizi section within Mbarara municipality, Uganda, were assessed using multivariate statistical methods. This river section is a major source of water for the inhabitants of Mbarara municipality. Water samples from five sites were analyzed for physicochemical parameters such as pH, EC, turbidity, temperature, TSS, TDS, alkalinity, salinity, colour, NH 3 -N, 2 4 SO − , total hardness, BOD, COD, DO, Ca, Mg, Fe, and Mn. About 50% of sites recorded colour above 800 Pt Co, 60% of sites recorded turbidity above maximum permissible limit of 100 mg/l, attributable to erosion and mineral matter. pH for dry season ranged between 6.5 and 8.5 whereas for rainy season was below 6.0. All study sites recorded total Fe above 0.3 mg/l and Mn below 0.5 mg/l, attributable to chemical weathering of host rock materials as well as from industrial effluent. About 60% of sites recorded COD above 100 mg/l, 40% and 80% of study sites showed BOD above 50 mg/l in dry and rainy seasons respectively. Hardness ranged between 50 and 100 mg/l indicating that the water is moderately soft. Colour, turbidity, alkalinity, TSS, TDS, salinity, pH, hardness, Fe, Mn, NH 3 -N, BOD, COD, and DO were higher in rainy season, as a result of erosion, discharge of domestic and industrial waste. Mg, Ca, and 2 4 SO − were higher during dry season due to high evaporation of water from the river. PCA/FA determined that 81.2% of the total variance was explained by the first factor for the dry season and 69.2% for rain season. These results revealed that water pollution resulted primarily from domestic waste water, agricultural runoff and industrial effluents.

The Physico-Chemical Quality of Effluents of Selected Sewage Treatment Plants Draining into River Rwizi, Mbarara Municipality, Uganda

“…Traversing Mbarara Municipality is river Rwizi which originates from the hills of Buhweju transecting through districts of Mbarara, Sheema, Ntungamo, Isingiro, Kiruhura, and Bushenyi before it pours its waters into Lake Victoria via the network of Lake Mburo, Lake Kachera, Lake Nakivale and Kijanebalola among others. River Rwizi is the main Source of domestic water supply and drainage system for Mbarara Municipality [7]. Sewage effluent samples were obtained from the two divisions of Mbarara Municipality that is Kakoba and Kamukuzi which have sewage plants i.e.…”

The Physico-Chemical Quality of Streams and Channels Draining into River Rwizi, South Western Uganda

“…Different studies have been done on River Rwizi mainly for a small part of the River in Mbarara Municipality with results indicating higher physicochemical parameters of the river than the NEMA standards attributable to pollution from domestic, waste water, agricultural runoff and industrial effluents [12] [13].…”

Pollution mapping in the urban segment of a tropical river: is water quality index (WQI) enough for a nutrient-polluted river?

“…Khan et al (2016) applied correlation analysis, PCA and CA components for identifying possible pollution causes, studying the seasonal variations and clustering of monitoring places of Yamuna and Ganga Rivers in Uttarakhand State of India. These statistical techniques have previously been used and approved by different workers at different regions/rivers systems (Diamantini et al 2018;Nguyen et al 2017;Ojok et al 2017;Chowdhury et al 2016). Statistical approaches like PCA and CA methods were used for classifying the sampling sites and identifying the underlying pollution source (Najar et al 2017;Xue et al 2017; López-Morales and Mesa-Jurado 2017).…”