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The Nile is Sudan’s most prominent topographical feature and the country’s primary source of water. It has two major tributaries: the White Nile, which originates in the Great Lakes
region of central Africa, and the Blue Nile, which begins in the Ethiopian Highlands. The two tributaries meet at the capital Khartoum, from where the river is called the Nile as it continues northwards into Egypt. The White Nile gets its name from whitish clay that is suspended in its waters. When the Nile floods, deposits of silt act as a rich fertilizer for the soil.
Other important tributaries of the Nile are the Atbara, Dinder and Rahad. There is also a group of large seasonal wadis, including Wadi al-Malik, Wadi Hawr, Wadi al-Magadam and Wadi Azoum in the west, and Wadi Khor Baraka and Wadi al-Gash in the east. Several other wadis flow from the Red Sea Hills westwards into the interior and, conversely, from the west towards the sea.
The vast plains in central Sudan are bordered on three sides by mountains: the Red Sea Hills to the north, the Marrah Mountains to the west and the Didinga Hills to the east. The Red Sea Hills represent the western edge of the Great African Rift Valley, which stretches from East Africa across the Red Sea to the Jordan River Valley and the Sea of Galilee in Israel. The volcanic highlands of the Marrah Mountains rise out of the Darfur Plateau to elevations of
between 900 and 3,000 metres above sea level. In south-central Sudan, rugged granite hills rise sharply from a wide clay plain, the largest group of which forms the Nuba Mountains.
Sudan’s landscape is characterized by isolated mountains and hills that rise up suddenly from deserts and clay plains. These are mostly the remnants of igneous or sedimentary rocks from different geological eras that withstood erosion.
Sedimentary rocks are found in large parts of the country. Nubian sedimentary rocks cover large parts of the northern, eastern and western regions. Volcanic rock formations are scattered across the north and along the eastern border with Ethiopia. Modern sediments of mudstone, sandstone, clay and iron also cover large areas.
The oldest geological formations belong to the Precambrian period, represented by basement rocks, and cover most of the eastern, western, central and southern regions. Dating from the first and second geological era, especially the Cretaceous period, are the Nubian sandstones that cover vast areas of the northern and central regions. In the central region is the Um-Rawaba, a formation rich in groundwater that dates from the third geological era. Rock formations settled throughout the fourth geological era up to the present day.
Climate and Climatic Regions
Rainfall in the central and eastern parts of the country ranges from less than 100mm north of Khartoum to 1,000mm in the far south. The eastern plains derive most of their heaviest rainfall from winds coming from the east.
Sudan has enormous water resources, including 1,000 billion cubic metres (BCM) of annual rainfall and 1,085BCM of Nile water, in accordance with the 1959 water-sharing agreement signed with Egypt. However, water is scarce during the dry season in areas that are not located on the river. The amount of renewable groundwater is estimated to be around 4.02BCM.
Two thirds of northern Sudan is affected by desertification, largely as a result of decreasing rainfall, soilerosion and deforestation. In addition to natural factors, human activity is exacerbating the problem, especially overgrazing, agricultural expansion and logging. Land affected by desertification is confined to areas between latitudes 10-18 degrees north, comprising a total area of 126,000 square kilometres or roughly 51% of the country’s total area.
Other environmental issues include deteriorating water resources, periodic droughts, pollution caused by herbicide and pesticide use, loss of biodiversity and declining wildlife populations due to excessive hunting.
Projects launched by the General Directorate of Energy Affairs, the Energy Research Institute and the Community Development Fund have been able to install around two megawatts (MW) of solar energy in remote rural areas. The government aims to increase that amount to around 20,000MW within the next 20 years.