The terrain is generally flat plains, broken by several mountain ranges; in the west the Jebel Marra is the highest range; in the south is the highest mountain Mount Kinyeti Imatong, near the border with Uganda; in the east are the Red Sea Hills. The Blue and White Niles meet in Khartoum to form the River Nile, which flows northwards through Egypt to the Mediterranean Sea. Blue Nile's course through Sudan is nearly 800 km long and is joined by the rivers Dinder and Rahad between Sennar and Khartoum. The White Nile within Sudan has no significant tributaries.
The amount of rainfall increases towards the south. In the north there is the very dry Nubian Desert; in the south there are swamps and rain forest. Sudan’s rainy season lasts for about three months (July to September) in the north, and up to six months (June to November) in the south. The dry regions are plagued by sand storms, known as haboob, which can completely block out the sun. In the northern and western semi-desert areas, people rely on the scant rainfall for basic agriculture and many are nomadic, traveling with their herds of sheep and camels. Nearer the River Nile, there are well-irrigated farms growing cash crops.
Sudan (officially the Republic of Sudan) is a country in northeastern Africa. It is the largest in the African continent and the Arab World, and tenth largest in the world by area. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, Kenya and Uganda to the southeast, Democratic Republic of the Congo and the Central African Republic to the southwest, Chad to the west and Libya to the northwest. The country's name derives from the Arabic Bilad-al-Sudan, literally "land of the blacks." Sudan has recently emerged as the world's most unstable country according to the 2007 Failed States Index, mainly due to its military dictatorship and the ongoing war in Darfur.
Despite being the 17th fastest growing economy in the world, new economic policies, and infrastructure investments, Sudan still faces formidable economic problems as it must rise from a very low level of per capita output. Since 1997, Sudan has been implementing the macroeconomic reforms recommended by the IMF. In 1999, Sudan began exporting crude oil and in the last quarter of 1999 recorded its first trade surplus. Increased oil production (the current production is about 520,000 barrels per day (83,000 m³/d)) revived light industry, and expanded export processing zones helped sustain GDP growth at 6.1% in 2003. These gains, along with improvements to monetary policy, have stabilized the exchange rate. Currently oil is Sudan's main export, and the production is increasing dramatically. With rising oil revenues the Sudanese economy is booming at a growth rate of about 9% in 2007. Sustained growth is expected next year, not only because of increasing oil production, but also due to the boost of hydroelectricity (annual electricity yield of 5.5 TWh) by Merowe Dam, which will produce energy later this year.