The Nile Basin Initiative, established in 1999, has initiated the preparation of the Nile Basin Water Resources Atlas as part of their quest for basin-wide cooperation, enabling water resource management and water resource development. The primary objective of the Atlas is to support collaborative monitoring the water and related resources of the Nile Basin by Riparian States and thereby contribute towards achieving their shared vision objective “to achieve sustainable socio-economic development through the equitable utilization of, and benefit from, the common Nile Basin water resources”.
The Atlas provides a snap-shot of the present water resources situation and aims to give overviews of the conditions and the huge variations in water resources parameters in the Nile Basin that is roughly 10% of the African continent and comprises eleven countries. In such a huge area with large variations the Atlas will give aggregated information. The Nile flows from its spring in the highlands southwest of Lake Victoria and join the Kagera River, which empties into Lake Victoria. Totally the Nile flows roughly 6700 km to the north before reaching the delta and eventually the Mediterranean Sea. The physiography of the basin represents the result of the processes, which have formed the landscape over millions of years. In historical time, humans have started influencing erosion and sedimentation, land cover, soils and the wetlands. The physiography divides the Nile Basin into two broad sub-systems. The Equatorial Nile sub-system comprises the sub-basins of Lake Victoria, Lake Albert, Victoria Nile, Bahr el Jebel, White Nile and Bahr el Ghazal. The Eastern Nile sub-system comprising the Main Nile sub-basin and the sub-basins of Tekeze-Atbara, Blue Nile and Baro-Akobo-Sobat. Totally, there are ten sub-basins with large variations in characteristics. The Nile and its tributaries is the lifeline for a population of 257 million or more than 10% of the population of the African continent. The Nile and the socio-economy of the 11 riparian countries are intimately connected. Agriculture, hydropower production, wetlands, water supply, navigation, fisheries and tourism are among the many sectors depending on water resources and providing livelihoods for the riparian population.
The settlement patterns also reflect the availability of water, which seems to overshadow other factors such as social and economic infrastructure. In the downstream countries, population is concentrated along the course of the Nile and in the Nile Delta. Upstream population densities are highest in the Equatorial Lakes region and in the Ethiopian Highlands, both being regions of high rainfall and abundant water resources. The trend in migration is from rural areas to urban areas. For the Nile Basin as a whole, the rural population is larger than the urban population. Projections for 2050 shows that the urban population will reach above 60% of the total population in 4 of the 11 Nile Basin riparian nations. In the remaining seven nations the urban population will increase but stay well below 40%. Urbanization will increase the pressure on urban services and facilities as well as on the natural resources and the environment. Water pollution will be one of the serious challenges for the water resources management.
The Human development index (HDI) is an aggregation of the average achievement in the key dimensions, a long and healthy life, being knowledgeable and having a decent standard of living. All Nile Basin countries fall into the Low Human Development category with the exception of Egypt, which is in the middle category. However, all basin countries show improvements compared to year 2000. The higher the HDI, the higher the potential for involvement of the broad population in the stewardship of the environment, the water resources and the battle against water pollution. Poverty is widespread and by income, around 40% of the population of the basin countries live below a poverty line of USD 1.25 per day.
The full dependence of the socio- economy on shared basin water resources makes a fact based management and development essential. Monitoring of water resources is therefore done by all countries and close to 1,000 meteorological stations for rainfall and temperature recording exists. Almost 450 hydrometric stations for gauging of streamflow were registered. Technical and financial resources to operate the networks of stations have been dwindling in most countries and station densities can become inadequate. The need for improvements have been realized by the Nile Basin Initiative, which has completed a design of a Nile Basin Regional Hydromet System based primarily on upgrading of existing stations adding water quality monitoring and laboratory strengthening. Groundwater monitoring is generally very sparse. Automated water level registrations and telemetric transfer of data are still underused. Calibration of hydrometric stations is often not adequate and data reliability suffers.
Climatically, the Nile Basin has large variations ranging from the tropical climate in the Equatorial Lake region to the Mediterranean climate of the Nile Delta. This is brought about by the latitude range (4o S to 32o N) and the variation from sea level to an altitude of around 3,000 m. Regarding rainfall, the Equatorial Lakes region and the Ethiopian Highlands receive an average annual rainfall above 1,000 mm, while the high altitude areas (Rwenzori mountains, Mount Elgon and the Ethiopian Highlands receive an average annual rainfall in excess of 1,500 mm. The northern part of Sudan and Egypt receives less than 50 mm and there are years, which are completely dry. This accentuates Egypt’s and Sudan’s full dependence on a steady flow of the Nile as very little surface runoff is generated there. Temperature is a significant factor in for instance evapotranspiration and is, together with water, essential for plant growth. In the Equatorial Lakes region and the Ethiopian Highlands, maximum temperatures are recorded in the range of 30oC while parts of the Blue Nile, Tekeze-Atbara and the White Nile in Sudan are measuring maximum temperatures of 45oC. High temperatures entail large evaporation losses from water surfaces like lakes and reservoirs.
Climate change as a result of global warming, is a challenge for water resources management and development. Adaptation is the immediate response to climate change and trends and statistics have to be closely monitored as they are no longer stable. Even small changes in temperature averages or extremes can have serious consequences for water resources availability, floods and droughts, agriculture, power and transportation systems, the natural environment and even health and safety.
The Nile Basin streamflow patterns are influenced by the variations in meteorological parameters such as rainfall and evaporation as well as by the physiography in terms of among others, topography, land cover, soils and geology. This is evident when comparing the White Nile and the Blue Nile being key tributaries to the Main Nile. The Blue Nile is highly seasonal with most of its flow occurring between July and September, while the White Nile flow is almost stable over the year mainly due to the regulating effect of Lake Victoria, Lake Kyoga, Lake Albert and the Sudd (a huge wetland in South Sudan). The Blue Nile contributes almost 160 percent of the annual flow of the White Nile and has a large potential for development of dams and reservoirs, among others, for hydropower production. Seasonality is a dominant hydrologic feature in the Nile riparian nations. This exposes the countries to floods and droughts with a devastating effect on the national economies and the affected communities. Kagera River is the southernmost river discharging into Lake Victoria. The reservoir effect of Lake Victoria makes the outflow almost constant and Jinja Dam is operated to simulate the natural outflow of roughly 900 m3/s as an annual average. The Nile continues through Lake Kyoga and the surrounding wetlands and run through a stretch with a good hydropower potential before it joins Lake Albert at Murchison Falls. The Nile continues through South Sudan and enters the Sudd, one of the largest wetlands in the world. A huge amount (approx. 50%) of the Nile inflow is lost to evaporation when passing the Sudd. The Nile proceeds towards Khartoum, where it is joined by the Blue Nile and now, combined flows of close to 2300 m3/s are recorded. The last significant contribution to the Nile flow comes from the Tekeze-Atbara Sub-basin where about 350 m3/s is received on the average. The Nile enters the reservoir created by High Aswan Dam. The reservoir, Lake Nasser, has capacity to regulate Nile flows on an inter-annual basis, but causes a huge water loss by evaporation estimated at roughly 10 – 12 BCM on the average. The Nile ends its 6700 km journey at the two branches at the Delta and close to 12BCM reaches the Mediterranean Sea – with a good proportion of this volume being drainage water from irrigation fields in Egypt. Surface water quality is mainly influenced by human activities relative to urban areas and industrial activities. Sediment production takes place in the upland areas with the Ethiopian Highlands as the main source compared to other parts of the Nile Basin.
Another source of water is groundwater, which is, however, not well studied and inadequately exploited. The most significant groundwater aquifer is the Nubian Sandstone underlying part of Egypt, Sudan, Chad and a part of Libya.
The water resources in the basin are essential for sustaining life, the economy and a healthy environment. Water is used off-stream (withdrawn e.g. for agriculture or domestic use), in-stream (e.g. hydropower, fisheries, environment) or on-stream (e.g. transport, tourism). The total area under irrigated agriculture in the Basin is estimated at 5.4 million hectares – over 97percent of the area lie in Egypt and Sudan.
By far, the largest consumptive use is for irrigation, which has been estimated at 82 BCM per year with over 96 percent of this occurring in Egypt and Sudan. In a region that is beset with strong seasonal and inter-annual variation of climate, storage dams provide one way of reducing vulnerabilities of water use sectors to climate shocks. The total storage capacity of dams in the Nile Basin is estimated at about 200 BCM. Water demand for municipal and industrial use, estimated at 12.9 BCM per year is rapidly increasing from the present estimates of roughly 400 m3/s. Forecasts for 2030 are expecting a five-fold increase and the Nile Basin population seen as a whole, will become unable to meet the water demand. The Nile Basin is expected to undergo substantial changes as more and more hydraulic infrastructure is realized to meet the growing water demands the riparian states. According to consulted national planning documents, the total storage capacity of dams in the Basin is expected to double by around 2040 – 2050; total area under irrigation can grow to 8.7 Million Hectares – an increase of some 60 percent of current size of irrigated areas; aggregate installed capacity of hydropower plants is expected to grow from a current value of 5600 MW to over 25,000 MW.
Unless actions are taken to enhance the water supply and manage the growth of consumptive demands, in a not too distant future, the Nile Basin will thus be in a critical situation, where increases in consumptive use in one sub-basin will have to be covered by decreases in consumptive use in another sub-basin and reallocation of water will have to be negotiated. Changes in climate could very well aggravate the situation. These conditions require a very high degree of trust, cooperation and sharing of water and benefits between the riparian nations. The Nile Basin Initiative has a vital, strategic mission in facilitating the cooperation, promoting Integrated Water Resources Management, providing access to Decision Support Systems and reliable databases and raising awareness on known or innovative ways of demand management, water conservation and efficiency in water use.