Rainy seasonal analysis of Physico-chemical parameters of Mukungwa River at NGARU point
Abstract
Water availability and quality are important factors that determine not only where people can live, but also the quality of life. The Mukungwa river is affected by rainy season especially at Ngaru point before discharge in Nyabarongo river, where its physico – chemical properties are seasonally changed. This may cause serious problems on all forms of life in the river. Objective of this work was to assess the impacts of rainy season on physico-chemical properties of Mukugwa River before discharging into Nyabarongo River at Ngaru. The parameters such as pH, temperature, turbidity, electric conductivity, total dissolved solids (TSS), phosphates, nitrates, and ammonium were monitored in three rainy seasons: April, 2012; October, 2012 and May, 2017 respectively. In this research, pH, temperature, electric conductivity were analyzed in situ using multifunction pH-meter and others parameters, were analyzed in laboratory using electrometric, volumetric, turbidity tube and colorimetric methods. The measured values for each parameter in three seasons were analyzed using MS Excel, and then compared to their international standards for surface water delivered by World Health Organization (WHO). The findings showed high variation of TSS (134mg/l, 178mg/l, and 582mg/l), turbidity (322NTU, 317NTU and 1560NTU) and ammonium (0.498mg/L, 0.536mg/L and 0.78mg/L) in three rainy seasons assessed. The quality of Mukungwa River needs prevention measures in order to control its pollution by erosion.
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Introduction
Surface waters include lakes, rivers, streams and reservoirs (Meybeck & Helmer, 1996 ). Physical, chemical measurements can be used together to describe the overall quality or health of aquatic ecosystems. Many factors influence water quality including climate and precipitation, soil type, geology, vegetation, groundwater and flow conditions as well as human activities (Sahuquillo, 2017).
The availability and quality of water always played an important part in determining not only where people can live, but also quality of life (Weaver, Granato, & Fitzgerald, 2019). Water is needed for agricultural, pastoral and industrial as well as for human consumption both in rural and urban areas, for socio-economic development purposes. It is used as a source of hydroelectric energy and for river and lake transport (Michel, 1993). All these forms of use have often harmful consequences on water resources which are often characterized by physical, chemical and biological disturbances (Castree, 2006). Rivers are like roads carrying water, organisms and important gases and nutrients to many areas. They help drain rainwater and provide habitats for many species such plants and animals (Michel, 1993). Aquatic environmental chemical phenomena involve chemical processes, including acid-base, solubility, oxidation-reduction, and complexation reactions. The chemistry of rivers is complex and depends on inputs from the atmosphere, the geology through which it travels and the inputs from man'sactivities (Manahan, 2000).
According to (KABALISA et al., 2005), Water pollution in Rwanda is mainly coming from domestic waste, agro-pastoral and industrial activities. In Rwanda water resources are very important for sustainable development. Hence the Rwanda Government puts high priority in monitoring the quantity and the quality of the water resources in the country (KABALISA et al., 2005).
Based on the field observation, the selected study area is densely populated and mountainous which resulted in serious problem of erosion in the rain season. The crops such as rice, bananas, and beans were the most agriculture forms applied around the river. Through erosion, soil, organic materials, plant nutrients from agriculture, micro-biological pollution from domestic wastes and destruction of latrines at home, may change the quality of Mukungwa river water at this site. This may lead to the contamination of aquatic biota in the River as well as human health. That is why physico – chemical analyses have been conducted, to assess the impacts of rainy seasons on the quality of natural water resources in Rwanda especially in Mukungwa river at Ngaru point. The Mukungwa River water quality is affected by chemical pollution from human activities around the River. This research has been conducted on Mukungwa River; to analyze the change of physical and chemical parameters in rainy seasons before discharging in Nyabarongo River at Ngaru. The main cause of water pollution will be identified and its impact on environment, then formulate recommendations.
Conclusion
The study showed high variation of TSS (134mg/l, 178mg/l, and 582mg/l), turbidity (322NTU, 317NTU and 1560NTU) and ammonium (0.498mg/L, 0.536mg/L and 0.78mg/L), in three seasons analyzed compared to their world health organization standards on surface waters. Other parameters their seasonal changes were below standard values and present no concern about the protection of aquatic life. The quality of Mukungwa River needs prevention measures in order to control its pollution by erosion. This paper gives information on impact of rainy season on Mukungwa water quality to future researchers and decision makers to protect natural waters and regular monitoring of river waters in Rwanda. Based on the above conclusions it can be recommended that: The Rwandan government should take efforts for natural water resource monitoring each year in order to detect any new pollutant released in Rwanda water resources and to evaluate its source, hence take protective decisions. As general observation, all contaminants originate from anthropogenic activities. It is in that regards that Rwandan population should be mobilized about water and sanitation measures in order to protect our water resources from pollution. From field based observation, Mukungwa river basin is highly populated and mountainous affected by erosion which collects all materials from homes and bring them into river. So people around there should grow many trees to prevent erosion. Mukungwa River is really contaminated by chemical pollution. People around the river, must be informed that the Mukungwa water is not safe for domestic uses except for irrigation.
Due to the data available and instrumentation, we have been limited to analyze other chemical parameters, but we recommend future researchers to expand parameters to be seasonally analyzed.
