Water of the Nile (The quality) 1 By Bashir Mohamed El Hassan 2 and Isam Mohmed Abdel-Magid 3 Introduction It has always been assumed that the water of the Nile and its tributaries are safe from chemical, physical and bacteriological points of view. This assumption was mainly based on the rather limited water and land usages in contrast with the abundance of available water. This led to the rather indiscriminate use of water. The consequences, of such attitude, resulted in gradual deterioration of water quality, spread of water-related diseases and water shortages. This has been magnified by negligence, unawareness, lack of health education as well as lack of sound environmental planning for water resources. The research that has been carried so far by different health authorities suggested a direct link between water quality and the health status of the inhabitants. The increase in water use without proper water management and the adopted irrigation practices resulted in an increase of prevalence of certain diseases such as diarrhea, malaria, infectious hepatitis, typhoid, schistosomiasis, gastroenteritis etc. Table 1 shows incidence of some water related diseases prevailing in some provinces in the Sudan: Table (1) Incidence of some water related diseases in some provinces of the Sudan. Disease % infected population of total province population Khartoum Blue Nile El Gezera Malaria 6 10 5 Eye diseases 6 5 3 Diarrhea NA 4 6 Dysenteries 5 4 3 Schistosomiasis 0.5 1.5 3 Typhoid NA 0.1 NA Infectious Hepatitis 0.4 0.5 0.3 No. of population per province (millions) 1.8 1.06 2.04 1 Published in the Proceeding of International; Conference on Water Resources Needs & Planning in Drought Prone Areas, Khartoum, Dec. 1986, pp 609-619 2 Dean, School of Hygiene, Khartoum, Sudan 3 Civil Engineering Dept., Faculty of Engineering & Architecture, University of Khartoum, Sudan 609
Historical Background: This could be divided into two phases: Phase (1): It relates to the work that has been carried out by the Welcome Laboratories by Beam and others {1}. Phase (2): Started in 1953 by the establishment of the Hydro biological Research Unit (Talling and others, 8). The former work has been carried out with a bias to the health impact and relationship; whereas the latter work has been conducted from an ecological point of view. Latecomers in this field included various research bodies and the water supply authorities. They covered to great extent health aspects, treatment methodologies and requirements together with consumer interests. Results and Discussions Based on literature survey that has been accumulated in the various governmental departments, private collections and laboratory investigations carried by postgraduate candidates in different faculties of the University of Khartoum, a general view has been adopted. This is to survey historically the documented obvious changes in Nile water quality with emphasis on physical, chemical, bacteriological and biological parameters. The gathered data were subjected to analysis in order to focus on the quality trend changes, if any, and try to identify reasons that would justify these changes. A. Physical Parameters: Certain parameters were stressed upon due to practical laboratory limitations. The emphasis followed for parameters that could indicate any suspected changes. The selected parameters included suspended solids concentration, turbidity value and conductivity measurements. It is to be noted that the significance of other parameters such as temperature, taste, odor and color etc., cannot be neglected. A. 1. Turbidity and suspended Solids: The measurements of turbidity for the Nile (as shown in Fig.1) revealed a seasonal fluctuation with a maximum occurring in July, August and September; while the minimum value resulted during December, January and February. The variation of suspended solids follows a similar seasonal variation to that of turbidity (Fig1) Figure (2) shows the general trend for dissolved solids variation for a span of ten years. The figures indicate the seasonal variation of turbidity and solids with a maximum during the food season and a minimum value during winter months. This could be attributed to the variable sediment load carried by the river during those months; as well as the mode of operation of dams along the river and the hydrological characteristics on the catchments areas The illustrated figures demonstrate also the trends of gradual increase of solids load over the years. This could be attributed, with reservation, to the changes that the river has been subjected to; such as dams control structures, agricultural schemes and industrial activities, 610
along with increase of settlements of inhabitants alongside riverbanks. Likewise climatic conditions play role. B. 2. Conductivity: Figure (3) reveals the general trend of variation over a period span of 20 years. It is clear that the persistent trend signifies a higher conductivity value for the White Nile in comparison to that for the Blue Nile. The reason behind this could be traced down to difference in characteristics of the catchment areas, pattern and origin of river flow, water and land use activities around the river basin. B) Chemical Characteristics: Although complete data on chemical analysis are available, yet the authors of this paper selected only those parameters that could be indicators of pollution or deterioration of river water quality. Therefore, picked parameters including chlorides, nitrogen compounds (N-NO 3 - ) and dissolved oxygen. Unfortunately data on trace compounds, pesticides and fertilizers are not attainable; since they are not performed on routine bases and due to absence of monitoring stations. B.1 Chloride concentration: Figure (4) shows the obvious differences in chloride content between the White and Blue Niles; with the higher concentration always found in the White Nile along the years. Likewise, there is a gradual build up in chloride concentration in both rivers for the chosen span of twenty years. For instance, in absolute terms, the chloride content of the Blue Nile increased from a value of 5 mg/1 (1961) to about 20 mg/1 (1981); an increase of approximately four folds. The White Nile increase in chloride content from about 8 mg/t to around 22 mg/l (approximately three folds) The significant increase in chloride content could possibly indicate a gradual buildup of pollution. This may be due either to natural or man-made activities. C. 2. Nitrogen compounds: (Organic and inorganic) The analysis of available data on nitrates, nitrites, ammonia, albimonid nitrogen suggests the absence of significant organic contamination over the years, This is contrary to the general belief. This may be ascribed to the high dilution factor and the rather efficient self-purification persisting in the rivers up to date. 611
D. 3. Dissolved oxygen: Figure (5) indicates the rather stable variation of DO over a span of ten years. This conforms to the findings regarding nitrogen compounds. C) Bacteriological Characteristics Table (2) shows bacteriological analysis of waters of the rivers in terms of fecal cloiform/100ml..the readings illustrate possible changes and seasonal variations. This could be reflection of effects of flow characteristics, flood, and catchment area contribution as well as effects of climatic factors such as temperature. Table (2) Bacteriological analysis waters of rivers in terms of fecal cloiform/100ml Blue Nile White Nile Main Nile 5 1000 2-1750 5-2000 Table (1) demonstrates the rather high prevalence of the reported water related diseases, which is a good indicator of the water quality and the improper environmental management; together with poor health educational level. Conclusions and Recommendations Graphs summarizing the findings of this paper show the seasonal variations as well as gradual changes in water quality of the Nile. These could be interpreted as being unfavorable conditions that if uncontrolled, or improperly managed, could lead to pollution of the water. The high subsistence of water related disease-vectors throw some light of the mismanagement as well as low socioeconomic status of the people. The deterioration of river water quality will undoubtly, interfere with any beneficial usages of the water locally and regionally. This calls not only for internal sound management of the river water quality, but also calls for close integration and coordination between countries of the river Nile basin. This is to activate the ongoing joint research among the countries of the river Nile Basin. References 1. Beam, W, Chemical Composition of Nile Water, 2 nd report, 1906, Nile waters, 3 rd report, 1908; Welcome Research Laboratory, Khartoum. 2. El Moghraby, A. I. (Edi), 1984, "Water and Land Use in the Blue Nile Basin", Institute of Environmental Studies, University of Khartoum. 3. El Zubeir, M.E.G 1985: A Study on the Supplied Water Quality at Khartoum", M.Sc. Thesis. Civil Eng. Dept. University of Khartoum. 4. Habiballa, H.I. 1981, " A Comparative Study of the Resources of Domestic Water Supply in Khartoum and their Associated Problems, M.Sc. thesis, Institute of Environmental Studies, University of Khartoum. 5. Mahgoub D.M. 1984, Coliform bacteria in the Nile at Khartoum:, M.Sc. Thesis, Inst. Environ. Studies, University of Khartoum. 6. Ministry of Energy and Mining, Records of water quality 1960-1986" unpublished data, Khartoum Central Laboratory. 612
7. Mohamed, Y.A. 1982 " Study of water quality for the Blue Nile and White Nile", M.Sc. Civil Eng. Dept, University of Khartoum. 8. Talling J. F. 1957 "The longitudinal succession of water characteristics, in the White Nile", Hydrobiologia J. Vol. XI(1). 9. The Chemical Laboratories-Ministry of Health records and data, Unpublished, 1955 1956, 1961 1972. 613
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