The Nile river basin is the longest river in the world (around 6,800 Km) and the third largest watershed worldwide (around 3.3 Million Km2) after the Amazon river basin (7.2 Million Km2) and the Orinoco river basin (3.8 Million Km2) (Williams, 2018). The Nile is a transboundary watershed that spans over 35° of latitude and crosses 11 countries: Burundi, Democratic Republic Congo (DRC), Egypt, Eretria, Ethiopia, Kenya, Rwanda, Sudan, South Sudan, Tanzania, Uganda. The Nile is the only river around the world that crosses a desert. The watershed has three main tributaries : the white Nile, the Blue Nile, and the Atbara. The white Nile originates in the Equatorial uplands in Uganda, Rwanda, and Burundi, from lake Victoria and flows through lake Kyoga (Uganda) and lake Albert (between Uganda and DRC), then the Sudd swamps in south Sudan until it reaches the confluence point with the Blue Nile in Khartoum Sudan. The Blue Nile and Atabra basin both originate in the Ethiopians highlands and contributes to 60 % , and 20% of the main Nile flow respectively (NBI, 2016; Pacini & Harper, 2016).
Figure 1: Map Showing the Nile Basin and Riparian States. Sources: Nile basin boundaries (Lehner & Grill, 2013), Countries boundaries (ESRI, 2021)
Although the Nile River is shared by 11 countries, the distribution is not equal. As shown in Figure 2, the Nile Basin covers nearly the entire territory of Uganda, followed by South Sudan (85.36%), Rwanda (75.46%), and Sudan (68.93%). In contrast, the basin represents only a small portion of other countries such as Tanzania (8.91%), Kenya (7.93%), and the Democratic Republic of Congo (0.94%).
Conversely, the extent to which each riparian country occupies the Nile Basin area also varies. According to Figure 3, Sudan holds the largest share, with slightly less than half of the total basin area lying within its territory (43.57%), followed by South Sudan (18.43%), Ethiopia (12.24%), and Egypt (10.95%).
Figure 2: Percentage of area included in the Nile Basin, compared to the total country’s area. Source: calculated from the map – Figure 1
Figure 3: Shares of Nile Basin area per country from the total basin area. Source: calculated from the map – Figure 1
References:
- ESRI. (2021, April 29). Africa Countries [Shapefile]. doi:https://hub.arcgis.com/datasets/africa::africa-countries/about
- Lehner, B., & Grill, G. (2013). Global river hydrography and network routing: baseline data and new approaches to study the world’s large river systems. Hydrological Processes, 27(15), 2171–2186. doi:https://doi.org/10.1002/hyp.9740
- NBI. (2016). Chapter 2- Nile Basin Physiography. In N. B. (NBI), Nile Basin Water Resources Atlas (pp. 21-48). Nile Basin Initiative (NBI).
- Pacini, N., & Harper, D. M. (2016). Hydrological characteristics and water resources management in the Nile Basin. Ecohydrology & Hydrobiology, 16(4), 242- 254. doi:https://doi.org/10.1016/j.ecohyd.2016.09.001
- Williams, M. (2018). 1 – The Nile Basin: An Introduction. In M. Williams, https://doi.org/10.1017/9781316831885.002 (pp. 1-7). Cambridge University Press. doi:https://doi.org/10.1017/9781316831885.002