UNESCO-IHP-International Sediment Initiative
Sediment in the Nile River System

Abdalla Abdelsalam Ahmed 
assisted by Usama Hamid Ahmed E. Ismail III 

Executive Summary

Water of course is everyone’s business. Hardly a day goes by, when we don’t hear of flood, drought or/and pollution spill into surface waters or groundwater. Each of these issues has a direct or indirect impact not only on human security but on livelihoods and development. The topic of this study is related to all these aspects and more. This report is the first attempt to study the Nile sediment at its regional level. It covers a wide range of issues related to sedimentation, with special emphasis on the Nile river system.

The main objective is to assess and understand the sedimentation process (erosion, transportation and deposition) in the Nile river system, and discuss its impact on the socio-economic development and the environment. Moreover, it serves as a practical reference in dealing with sedimentation and its related fields in the Nile Basin. This study does not propose to cover all or even most of the complex subjects like sediment in the Nile river system, but rather to shed light on the issue as a first effort in this respect. Sedimentation as an ecological and environmental phenomenon is increasingly affecting the sustainable development of human societies worldwide, especially in the Nile Basin.

The study is structured in nine chapters to cover in details the different aspects of the sediment in the Nile river system.

Capter One gives a background and introduction to the Nile river system and the Nile Basin countries.

Chapter Two presents the Nile river hydrology with details on its seven sub-basins. It gives in geographically and in tabular form the water flows through the Nile system. It should be realized that although the Nile is the largest river in the world, but not with much water. Its discharge is dwarfed by those of the Congo, the Niger, the Amazon, the Mississippi and the Mekong…etc.

Chapter Three explains the methods used to predict soil erosion and sediment yield, including the basic characteristics and monitoring. The chapter demonstrates the watershed degradation and sedimentation. It shows in details the rate of soil erosion and the portion that is delivered to the drainage system. The chapter documents on the erosion and land degradation in the ten countries of the Nile basin with emphasis on the Ethiopian Highland.

Chapter Four elaborates on the Nile bank erosion. The contribution of the bank erosion to the sedimentation process is explained. On the other hand, assessment of the extent, trend and impacts of the sand encroachment is also reported coupled with its influence on the agricultural land and the Nile water course. Reservoirs play a significant role in human society, including flood control, water supply, power generation, irrigation, navigation, recreation…etc. In the Nile system, especially tributaries with sediment-ladder, reservoirs lose a certain percentage of their storage capacity due to sedimentation.

In Chapter Five, the subject of reservoirs sedimentation and its socio-economic and environmental impacts is expanded upon. Sedimentation in seven selected existing reservoirs in the Nile system is discussed. Rosaries reservoir presented as a case study. Trap efficiencies for almost all the existing reservoirs are presented. Sediment management and the control methods in these reservoirs are elucidated. This chapter shows in brief the extent of reservoir sedimentation problems.

Future dams and reservoirs on the Nile river system are described in Chapter Six. This includes those under construction and planned dams. The sedimentation process, which is going to face these reservoirs, is fairly discussed. The expected life span of each of reservoir is estimated. As it is well known a considerable part of the Nile Basin is dry, therefore, irrigation is widely experienced. Irrigation networks suffer from sedimentation and management difficulties.

Chapter Seven explains the sedimentation problems in the irrigation canals and the interrelationship between the sediment and the aquatic weeds growth.

Chapter Eight deals with one of the most important issues, the socio-economic and environmental impacts of sedimentation in reservoirs and irrigation canals system. Gezira Irrigated Scheme experience, as the largest scheme in the world under a single management, is overviewed. Moreover, the effect of the sedimentation on the domestic water use plant treatment is explained. Therefore, water quality and sediment as pollutant, especially when dealing with safe drinking water, is highlighted.

Chapter Nine provides general concluding remarks on the study “Sediment in the Nile River System”.

Finally the document presents the References