Potential effect assessment of agricultural activities on water quality of rivers in Rwanda: “Case of Muvumba River in Nyagatare District”
Abstract
The problem caused by agricultural sector to Water Quality pollution remains a big challenge for Rwanda Government. The general objective of the study was to assess the potential effect of agricultural activities on water quality in Nyagatare District. Specifically, the study assessed agricultural activities in around Muvumba River, examine the level of water quality pollution in Muvumba River, and reveal the relationship between agricultural activities and water quality from Muvumba River. Data collected through interview, and laboratory tests of water samples applied once per month in three points sampling of Muvumba River. The action starting from 19th March 2019 up to 20th March 2020. To determine the correlation between agricultural input and Water Quality data at all selected physic-chemicals parameters, by Linear Regression Model using SPSS statistics with 95% confidence interval. The results indicated that agricultural activities on surrounding of Muvumba River, are presented by the existence of different type of crops, non-protection of anti-erosions, non-wetland margins, the farmers using chemical fertilizers and pesticides, the results revealed also that all selected parameters have not addressed positive relationship or pollution, but many of them did, as per to Rwanda Standards Board guidelines. For sampling point one has taken as baseline because it is upstream of Muvumba river at Nyagatare District, in sampling point 2, the parameters that presented pollution were; turbidity (r=0.193), nitrites (r=0.393), iron(r=0.122), manganese (r=0.008); for the sampling point3: were pH (r=0.319); turbidity (r=0.212); nitrites (r=0.143); nitrates (r=0.618); nitrogen ammonia (r=0.441); Iron(r=0.889); manganese (r=0.269); agricultural activities in surrounding of Muvumba River have significantly contributed to the water quality pollution of Muvumba River, through substances of chemical fertilizers, crop residues, and soil sediments that are transported into the River by erosion. Conclusion of the study that creation of anti-erosions in a surrounding Muvumba River areas, protection of buffer zones, performing vegetation covers, inducing water management bodies at cells level, introducing awareness of farmers how ecosystem functions.
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Introduction
The Water its function in ecosystem is to provide the lifeblood of the community, in the ecosystem makes water a key element for sustaining life as it is fundamental building block that supports biochemistry of all life in the planet (Laurie Brenner, November 15 2019).
In ecosystem Water is very important in lifeblood of the all live in the planet (UNESCO, 2006). It is a basic element for all forms of life for various uses such as drinking, cleaning, as a reproductive medium and as habitat for aquatic organisms and for irrigation purposes (Ninhoskinson, 2011). Water has 70% of the Earth’ssurface, and 40% of the population in the world, has shortage of Water.
The causes of this water shortage is the absence of freshwater, 95.7% water in the Earth is saltwater, and 2.5 % of water is fresh, while 70% of the freshwater is in the form of ice(Sandi, 2012). The World Health Organization (WHO), quoted by Mmbando J.et al (2007), under 1 % of Water which is able to be used by the different activities of the human. The main sources of the freshwater which is easy to access fund it in Lakes and river, but 25% of the users in the Earth relying on groundwater or deep aquifers for water supplies (Mmbando J.et al 2007). In the world there is no regular to supply freshwater to the users. The areas with the least available Water include most Africa, the Middle East, Asia and Europe. There is augmentation of famine, hunger and poverty. Population growth is greatest in Low Economic Developed Countries (LEDCs), and this accelerates environmental degradation and poverty. In LEDCs Half of all the populations, do not have safe water to drink. Waterborne diseases kill 25000 people’sdaily, and about 14 million children under five-year old die each year from illness and hunger (Mmbando J.et al (2007). However, the benefit of safe water for human is highly; generally are main source of water pollution, through outdated farm management activities The activities of Agriculture, is cited as one of biggest source of water systems deterioration and pollution, (MOSS, 2008). The Agricultural nutrients from farmlands are one of the top running contributors to the poor quality of water. An intensification of agricultural production generally produces an increase of externalities and potential for these by-products to, negatively, affect water quality (Ninhoskinson, 2011). The degradation of water quality by agricultural activities creates hazard life in downstream and requires tuff investments in water analysis and treatment infrastructures (Batchelor, 2000). The limited areas for agriculture activities is the barrier of adequate distance between farmland and water sources; the result from agricultural product through using varies fertilizers; manure and pesticides and mobile soil particles; each of these groups has serious negative impacts on degradation of both ground and surface water on the site and downstream(Libby, 1990)
Conclusion
The agricultural activities around Muvumba River and quality of water, used SPSS to determine the correlation between them; the result have indicated that there was positive relationship between these variables in sampling points, P2 and P3 compared to P1which is considering as water quality baseline in Muvumba river, and Rwanda Standard Board limit,. Talks about this relationship, all parameters have not presented pollution, but some of them did according to the positive correlation and Rwanda Standard Board guidelines. The parameters which had positive relationship for the sampling point two (P2) are turbidity (r=0.193), Nitrites (r=0.393), Iron (r=0.122), Manganese (r=0.008, and sampling point P3, the parameters that indicated positive relationship between agricultural input and result from water quality. parameters, were pH (r =0.319), turbidity (r=0.212), nitrites (r=143), nitrates (r=0.618; nitrogen ammonia (r=0.441; iron (0.859); manganese (r=269.
Briefly, agricultural activities in surroundings of Muvumba River, where characterized different crops, unprotected of anti-erosion structures, inefficient management of Muvumba marshland margins (buffer zones), utilized of chemical fertilizers and pesticides, and appearance of different types of rocks and soils. All these have contributed to pollution of water in Muvumba River.
The result demonstrated by the coefficient of correlation between agricultural inputs and water quality parameters such as pH; turbidity, nitrites, nitrates, Iron, manganese; nitrogen ammonia presented positive relationship between them; therefore, the research hypothesis confirmed that the agricultural activities have affected the pollution of water quality of Muvumba river. For sustainable wetland management the researcher suggested the following: Creation the protection anti-erosions in surrounding Muvumba river areas. To make a buffer zone land use in marshland of Muvumba river, through sensitizing local community and educating people using croplands surrounding Muvumba river in a way respecting Marshland margins (buffer zone) and have minimum knowledge the causes of water pollution. referring to the law on wetland protection applicable in Rwanda, To sensitize population the way to manage the agricultural wastes for protecting water to be polluted. To advise the district planers to consider long-term development matters, in order to sustain economic development of district; agricultural policy should not only be focused on the increase food production but also considering water quality stability. To consider environmental protection during the activities of agriculture and avoid the activities which can contribute to the pollution of water quality from the resource. To create the activities anti-erosion in order to maintain rainwater. Collaborate with district agronomist in order to take action of farming in order to be conformity of laws governing the use of land. To prepare agricultural activities which is not degrading the soil and the water quality. To mix organic manure with industries fertilizers in order to reduce induced by chemicals fertilizer and increase crop productivity. Create clubs for environmental protection in order to educate mass population about it.
