19 January 2021
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The Blue Nile And The Threats of Pollution


 Water bodies are vulnerable to pollutants such as heat, acids, detergents, hydrocarbons, heavy metals, agrochemicals and organic contaminants. Therefore, the determination of the water quality in our freshwater bodies, by testing for specific chemicals and certain variables, is an important task which must be carried out regularly. Algae can play an important role in the determination of water quality in rivers. Algal species composition and to a lesser degrees species richness respond sensitively to excessive nutrient loads, turbidity, pesticides and heavy metal contamination and therefore can be used as indicators of eutrophication and water pollution.

 The Nile is considered as one of the greatest natural resources of this country and should be kept clean. Its waters, for thousands of years, had been, and fortunately still are, of excellent quality for domestic use, irrigation, fishery, industrial use, navigation, tourism, bathing and recreation. The water quality for drinking is well within allowable limits set by the Sudanese Standards and Metrology Organization (SSMO). In view of the fact that Sudan, among other African and Arab countries, is regarded as a water-stressed country and in view of the fact that acute shortage of water may occur in the future, due to excessive demand and pollution threats, efforts need to be exerted to manage the available amount of water properly, so as to ensure water security for a variety of uses.

 In recent years (2000-2011), appreciable increases in the summer recurrent algal peaks of May-June have been noticeable features (Sinada, unpublished data). In May 2003, and January 2009 in particular, a profuse growth of a cyanobacterium (a blue-green alga) called Anabaena flos-aquae formed an unprecedented water bloom visible to the naked eye, was a cause of public concern. The occurrence of those unexpected cyanobacterial blooms cannot be explained. However, it is not unreasonable to assume that, unwelcome enrichment with nutrients from the catchment area during early showers in May, which may wash agricultural run-off through non-point sources or basement flow of underground water, might have been the cause resulting in mild eutrophication. Needless to say that this hypothesis concerning potential sources of contamination or any other hypothesis, needs to be verified through extensive sampling programmes of the Blue Nile and its tributaries between the Roseires Dam and Khartoum. 

 Sources of contamination

 There are many possible sources of contamination endangering the water quality of the Blue Nile. The river is used over a large part of its length by towns, industry and agriculture. There are numerous point sources of industrial effluents and non-point sources of contamination from surface run-off from agricultural land and urban storm water. Along the Blue Nile many factories were built during the past fifty years and certainly many more shall be built in the future. These factories include textile, sugar, tanneries, food, soap, and oil mills. Unfortunately, untreated waste waters from some of these factories with their impurities, nutrients and toxic compounds pour directly into the Blue Nile course (Desougi and Sinada, 1982). It is rather sad that the nature and quantities of industrial wastes discharged into the Blue Nile are not documented in any kind of publication. It is not unreasonable to assume that agricultural practices may adversely affect the water quality of the Blue Nile. In Sudan, for decades, increasing amounts of fertilizers, herbicides, insecticides and pesticides are constantly applied in Gazira, Managil, Rahad and other agricultural schemes. Sub-standard agricultural practices were adopted in which overdoses of fertilizers and pesticides are applied. Excess agro-chemicals falling on the soil are expected, eventually, to reach the Nile from diffuse sources during wet seasons.

 Agricultural chemicals were introduced into Sudan in 1940s in the Gezira scheme (AQUASTAT FAO, 2005). Since then, the application of chemicals has intensified and proliferated into other agricultural schemes and in the private vegetable and horticulture fields, as well as for control of desert locusts, birds and rodents. A total of about 200 active ingredients are registered in Sudan in over 600 different formulations of pesticides (AQUASTAT FAO, 2005). An average of about 450 tonnes of insecticides and 150 tonnes of herbicides were applied annually during the period 1993-1997. The annual consumption of fertilizers in the whole of Sudan is estimated at 80,000-200,000 tonnes of urea and 20,000-40,000 tonnes of super phosphate (AQUASTAT FAO, 2005). According to AQUASTAT FAO (2005) serious contamination has been detected in the Gezira canals as well as in boreholes in the Qurashi area (Hassahessa Province).


Although the River Nile is one of the longest rivers in the world, and possesses a network of hundreds of kilometers of water courses, it has received little attention, particularly the Sudanese stretches. Published data on the water characteristics and quality of the Blue Nile within Sudan are meagre. It is generally assumed that the development of any degree of pollution or contamination of the Nile within the Sudan has not occurred yet. This assumption needs to be verified. Lessons must be learned from pollution of water resources in developed countries which was detected over a hundred years ago. Sooner or later the Nile system within Sudan may be confronted with similar problems if not properly managed. Sinada and Abdel Karim (1984) agree that even a mild degree of eutrophication as a result of industrial and agricultural development could have adverse effects on the Nile because of the high temperature and radiation input. Therefore the prevention of deterioration of the water quality of the Blue Nile is a matter of urgency. This can be achieved through the regular assessment of water quality of the Blue Nile. A detailed continuous monitoring programme is needed to establish the status of the quality of the Blue Nile waters and other rivers, to detect changes and their causes, so as to give early warning of contamination. It is unfortunate that no national independent agency has been set up in the Sudan to monitor the physical, chemical and biological water quality of the Nile within the Sudan. Such studies could provide sufficient information on the ecology and water quality of our rivers that will help in pollution detection and control.

 Impact of deforestation of riparian vegetation

 The Blue Nile, as a sub-tropical river, is expected to support extremely dense and productive riparian vegetation. Riparian vegetation, which includes all plant communities along the river margins and banks, is extremely important because of the many functions it serves. It forms a buffer zone between the aquatic and the terrestrial ecosystems, playing significant roles in ecology and environmental management as bio-filters, thus maintaining high water quality in rivers. It occurs in many forms including grassland, woodland, and wetland. The riparian zone has many important benefits. To mention here but few, riparian vegetation stabilizes river banks preventing soil and bank erosion, and reduces wind speeds at the soil surface thus preventing the loss of nutrient-rich top soil. Trees and shrubs provide deep root systems which hold the soil and hold river banks in place, preventing erosion. The riparian zone prevents sediment reaching water bodies and traps agricultural diffuse pollutants in surface run-off water from reaching the Blue Nile, contributing to downstream water quality. For example riparian zones play a role in lowering nitrate and pesticide contamination in surface runoff from agricultural fields in waters reaching the Blue Nile. It reduces the risk of flooding since rivers in high flow can be slowed down by riparian vegetation alleviating flood problems. Riparian vegetation adds significant aesthetic value, increasing people’s enjoyment of the environment, and provides green recreation space.

 One of the major environmental threats to the Blue Nile within Sudan which must be researched, is the impact of deforestation of riparian vegetation. Vegetation clearing leads to degradation and erosion of river banks and siltation, which may cause considerable deterioration of the water quality of the Blue Nile. As a result of population increase along the Blue Nile banks, during the last 50 years, the riparian vegetation was much stressed by clearance of trees and shrubs for fuel, residential, bank farming and landscaping purposes as well as by grazing. Because of the many functions it serves, healthy riparian vegetation must be maintained along the banks of the Blue Nile. Therefore there is a need to update the meager information, fill gaps in our knowledge and establish baseline data about the riparian vegetation along the Blue Nile between Roseires and Khartoum so that this important buffer zone may be properly managed.

  Concluding remarks

 In conclusion, while the physical and chemical characteristics of the water of the Blue Nile did not change significantly during the past sixty years, nonetheless long-term physical, chemical, and biological monitoring programmes are recommended. The detection of unwelcome enrichment, which might occur as a result of introduction of industrial contaminants, or diffusion of agrochemicals into the course of the river, may serve as an early warning of deterioration of the water quality which needs urgent attention. No attempt has ever been made to evaluate the effect of stormwater and urban surface runoff on the water characteristics and quality of the two Niles at Khartoum or other major cities. It is highly recommended to carry out thorough studies to determine the impact on the Nile of stormwater and surface runoff of major cities and towns lying along the Nile and its tributaries.



 Desougi, L.A. and  Sinada, F. (1982) The Nile and the threats of pollution. Proc. 4th Conf. Nile Valley. University of Khartoum, Sudan.

 Sinada and Karim (1984) Sinada, F. and Abdel Karim, A. G. (1984) Physical and chemical characteristics of the Blue Nile and White Nile at Khartoum. Hydrobiologia. 110: 21–32.

 AQUASTAT FAO (2005) Irrigation in Africa in figures. Aquastat Survey, FAO Report No. 29, Sudan, Rome, 1-16.


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Dr. Faisal Abdalla Sinada FLS

B Sc (Botany), M Sc, Ph D

 Associate Professor, Department of Botany

 Faculty of Science

 University of Khartoum


Research interests: The status of the environment of the Main Nile, the Blue Nile and the White Nile and the threats of pollution, contamination and eutrophication. Bioremediation of produced water and refinery oily sludge to reduce the concentrations of TPH to desired limits.


Email: This email address is being protected from spambots. You need JavaScript enabled to view it.