Nile River Basin By Duaij AlRukaibi Introduction The Nile River Basin is a natural surface water system of strategic significant on the continent of Africa and an unrivaled historic, social, energy and economic important to ten riparian countries of Burundi, Democratic Republic of the Congo, Kenya, Uganda, Ethiopia, Rwanda, Tanzania, Eritrea, Sudan and Egypt. It is provide source of livelihood to over 300 million people for its riparian nation. Nile is the longest river in the world that is located in the north-east of the continent of Africa, and the track starts from the source at Lake Victoria “the third largest lake in the world” - the central east of the continent - and then heading north to the mouth of the Mediterranean, with a total length of 6695 km (4187 miles) and annual average flow 2622 m3s-1. Nile Basin covers an area of 3 million km². Returns the name “Nile” to Greek term called NEILOS.Background Nile river Basin covers roughly 10 % of the African continent or 2 % of the total earth land surface. With all 10 countries that Nile River flows through them, Egypt and the Sudan are the two major users of this river with small contributor to the runoff from Ethiopia. The three tributaries, the Blue Nile, the While Nile, and The Atbara are the feeders for the main Nile River. The White Nile flows from high in the mountain around Lake Victoria that shared by Uganda, Tanzania and Kenya and the Rainfall from them flow into the lake. The Nile leaves Lake Victoria and flows 3216 Km until reaches the capital of Sudan “Khartoum”. In the other hand, the Blue Nile River represent 80% of the water feeding Main Nile river but the water reached in the summer just after the monsoon rains on the plateau of Ethiopia while the rest of the year nearly dry. It originates from the highlands of Ethiopia at Lake Tana and flows 1400 Km to Khartoum, where the Blue Nile and White Nile join to form the Nile proper. River Atbara which originates in Ethiopia north of Lake Tana, and is around 800 Km (500 mi) long joined them at Atbara city to form the main Nile river that flows into Egypt‟s Lake Nasser, the second an artificial lake in the world created by the construction of the Aswan High Dam. North of Cairo, the Nile goes to split into two branches that feed the Mediterranean Sea: the Rosetta Branch “west” and the Damietta “east”, forming between them the Nile Delta.Hydrological features of Nile River Basin The annual runoff of Nile River is comparably low regarding to the size of the basin “3 Million Km2”. For example, Niger River has less than drainage area but its runoff much higher than Nile River that just represents 35.9% from Niger River‟s runoff. In the figure below that illustrated the elevation difference from Lake Victoria to Mediterranean Sea. Nile Basin constitutes a unique diversified geographically, starting from the highlands in the south and its decrease until the hike up to the spacious plains in the far north. Therefore, the Nile River is the only river which flows from south to north and that according to earth‟s slope. . Source: http://www.mbarron.net/Nile A natural flow in the Nile River is 2622 m3s-1 at northern Sudan Dongola (FAO 1997) but is subject to significant spatial and temporal variation (FAO 1997). Nile river basin is divided tofour catchments and each catchment has outlet except blue and while Nile have the same outlet but different flow (Table 2) Catchments Outlet Flow (m3s-1) Nile Aswan 2666.79 Atbar Atbara 351.97 Blue Nile Khartoum 1531.58 White Nile Khartoum 824.45 As statistics, spatial analysis or spatial statistics of water flow the main Nile which study entities using their topological, geometric, or geographic properties. The total flow reaching the main Nile “table 1” approximately 80 % stem from Ethiopian plateau and the rest from the equatorial Lakes plateau (Lake Victoria, lake Kyogo, Lake Kwania, and Lake Albert). In the Sudd area in southern Sudan half of water flow that outflow from Lake Albert (995.68 m3s-1) is evaporated. The major on the Nile these Roseires Dam and Sennar Dan in Sudan, Aswan High Dam in Egypt, and Owen Falls Dam in Uganda that help those riparian countries in different ways. In other hand, temporal analysis of water flow that inflow to Lake Nasser illustrates a keen seasonal pattern between July and November and stem from the Blue Nile and Atbara while low flow between February and May. The peak for inflow to Lake Nasser in September with 8102m3s-1 and during the dry season, the minimum flows close to 579m3s-1. Source: http://www.mbarron.net/Nile Population Growth Rising Water demands that is consequences from population growth in all riparian countries. In table 4 shows the population for riparian countries and 75 % from the total population live within the basin (CPNile 2006). There is a report for IPCC confirms for us that “by 2020, between the range of 75 and 250 million people are projected to be exposed to an increase of water demand due to climate change”.In the figure below that illustrates the population density per unit area within Nile basin of riparian countries (3112369 Km2). Overall, the value of population density increase in river valley in Egypt and where the White Nile and Blue Nile join each other. Two other spots that have intensity population, the Ethiopian‟s Highland and the city surround Lake Victoria in the south of the basin.Climate change impact: Nile river basin is sensitive to climate change and there are various factors that show this area expose for the change in the future. Along its 3000 Km through northern Sudan and southern Egypt, the Nile loses a huge amount of water due to evaporation that makes the basin extremely sensitive to temperature and precipitation changes. For the precipitation factor that different area in the basin don‟t receive significant amount like central and northern parts of the basin. In contrast, there are two main areas which supply almost 100 % of the water in the main Nile flowing to Aswan High Dam: the Ethiopian Plateau and Equatorial Lake Plateau. In table 5 shows the average rainfall over Nile River Basin is 615 mm a-1. According to Global Average coefficient of Runoff, the total runoff coefficient