Storage dams in the Nile Basin

Storage Dam in Ethiopia

Data obtained from NBI member states show that as of 2014, there are 14 storage dams basin-wide with a total storage capacity of about 203 BCM. The growth in aggregate storage capacities of all dams in the basin is shown in the adjacent figure. It is interesting to note that, after a period of four decades of near stagnation in dam construction during 1968 – 2007, the basin is witnessing more and more storage dams added to the system. In addition, the Owens Fall (Nalubalee) dam built at the outlet of Lake Victoria in Uganda provides an additional 200 BCM of live storage to the Lake. Dams on the Nile conserve water and provide sustained supply for meeting demands. Lake Nasser, in Egypt was formed after the construction of the Aswan High Dam in 1970. The total capacity of the Aswan reservoir (162 BCM) consists of dead storage of 31.6 BCM, active storage of 90.7 BCM and emergency storage for flood protection of 41 BCM. After the construction of the High Aswan Dam, completed in 1970, no storage was added to the Nile Basin till 2009 when the Tekezze dam with capacity of 9.29 BCM was built. Other storage dams constructed since then include, the Merowe dam (12.39 BCM capacities) and Roseries heightening (to 5.9 BCM) completed in 2009 and 2012 respectively. Bujjagali dam with capacity of 0.75 BCM was built in Uganda. In Sudan, the main reservoirs are the Jebel Aulia reservoir on the White Nile, Senar and Roseries storage reservoirs on the Blue Nile, Merowe reservoir on the Main Nile and Khashm El Girba reservoir on Atbara.

In 2012, work began on Ethiopia’s Grand Renaissance Dam, which has become the key project in the nation’s plan to increase its electricity supply fivefold by 2015. It will have an estimated installed capacity of 6000 MW, and a reservoir capacity (74 BCM). The dam together with its power house, when finished, will be Africa’s largest hydroelectric power plant.

Per Capita Water Availability in the Nile Partner States

Population growth, urbanization and socio-economic growth are the major reasons for the decreasing per capita water availability in the Nile Basin states. With per capita internal water resources availability less than 1000 m3, Sudan, Rwanda, Kenya, Egypt and Burundi can be categorized as water scarce. The per capita storage capacity of the partner states is low. These trends call for improved storage in these Nile Basin States.

With an aggregate basin-wide storage capacity of just over 200 BCM (excluding the Nalubaale dam), most of the Nile Basin countries have the least per capita water storage by world standards. In a region with severe seasonal and intra-annual variability and anticipated climate change, absence of adequate storage capacity means more vulnerability to impacts of climate shocks.

There is a trend between a country’s Human Development Index (HDI) and per capita water storage. Water storage in countries with a high HDI (>0.85) tends to be in the range of 2,500 and 3,000 m3/capita. Countries with HDI of 0.55 tend to have has a storage of about 173 m3 per capita.

Storage and Economic Performance in Kenya

Water storage has been positively correlated with performance of Nile economies. Where economic performance is closely linked to rainfall and runoff, growth becomes hostage to hydrology. Kenya’s limited water storage capacity leaves the country vulnerable to climate and hydrologic variability. Kenya’s total water storage capacity is 4.1 bcm, or 103 m3 per capita, which is very low. Of the estimated 103 m3 per capita, 100 m3 per capita is single-purpose storage for hydropower production only. This means that only 3 m3 per capita of storage is available for water supply and other uses such as irrigated agriculture and livestock. No major dams have been constructed since Ndakaini dam in the mid-1990s, which supplies water to Nairobi. Kenya also experiences significant hydrologic variability throughout and between years. Without sufficient water storage to lessen the effects of variability, frequent and severe floods and droughts have been resulting in devastating economic and livelihood consequences. Kenya, with a HDI of 0.548 in 2015, has a per capita storage of 103 m3, which is low (adapted from UNDP, 2015)

Storage and Economic performance in Ethiopia

GERD dam under construction
Storage and Economic performance in Ethiopia Hydrological variability seriously undermines growth and perpetuates poverty in Ethiopia. The economic cost of hydrological variability is estimated at over one third of the nation’s average annual growth potential, and these diminished rates are compounded over time. Yet, with much greater hydrological variability than North America, Ethiopia has less than 1% of the artificial water storage capacity per capita to manage that variability. Economy-wide models that incorporate hydrological variability in Ethiopia show that projections of average annual GDP growth rates drop by as much as 38% as a consequence of this variability. In Ethiopia, so sensitive is economic growth to hydrological variability that even a single drought event within a twelve year period (the historical average is every 3-5 years) will diminish average growth rates across the entire 12-year period by 10%. During the 1984–5 drought, for example, GDP declined by 9.7%, agriculture output declined by 21%, and gross domestic savings declined by 58.6%. Drought also severely undermines hydropower generation, Ethiopia’s main source of electricity. If rains fail, or simply come too early or too late, the entire agricultural cycle can be disrupted, because there is inadequate water storage capacity to smooth and schedule water delivery. Flooding meanwhile causes significant damage to settlements and infrastructure, and the inundation and water-logging of productive land undermines agriculture by delaying planting, reducing yields, and compromising the quality of crops, especially if the rains occur around harvest time

Evaporation from Dams along the Nile

Hydropower is one of the purposes most dams in the Nile Basin serve. The aggregate installed capacities of 22 hydropower plants basin-wide is approximately 5660 MW. The distribution of the existing hydropower installed capacity and annual generation capacity as of 2014 is shown in the figures below.

Hydropower offers an important low-carbon energy solution to meet the massive unmet demand and provides reliable baseload power in the Nile Basin states. Hydropower options remain the preferred source of energy in the region because they have long economic life which translates to very low per unit cost of energy and a renewable source of energy at that and with proper preparation of the reservoir, are pollution free and could be eligible for carbon credits.

Dam Period Net Evaportion 
Gebel Awlia 1950 – 2014 2.4
Khashm el Girba 1964 – 2014 0.190
High Aswan Dam 1970 – 2014 12.35
Fincha Dam 1973 – 2014 0.14
Koga dam 2007 – 2014 0.04
TK-5 2009 – 2014 0.18
Merowe 2009 – 2014 1.54
Amerti-Neshe dam 2011-2014 0
Roseries (heightened) 2012 – 2014 0.75
Alwero 1995 – 2014 0

Looking into the future, existing national plans indicate a substantial increase in installed capacity in the period 2017 – 2050. Projected growth in aggregate installed capacity in the Nile Basin is shown in the adjacent chart. The total increase in installed capacity by about 2050 will be over 20,000 MW bringing the total installed capacity to about 26,000 MW. Most of the increase is expected to be in the Blue Nile sub-basin. The GERD will inject 6000 MW of installed capacity. The Rusumo falls project, which is the first hydro-electric power project cooperatively implemented by Burundi, Rwanda and Tanzania with the facilitation of NBI will produce 81 MW.