Using a network of 18 geo-stationary satellites, NASA issues monthly very detailed maps of the Earth under the Blue Marble programme, thus monitoring the seasonal developments of Terra’s areas, as well as their long-term climatic changes. In March 2005 an overview of the African continent seen as ‘through an open window’ was possible by recomposing the photographs of the temporarily cloudless area (Fig. 1). The yellowish sand zones of the Sahara desert can be clearly distinguished towards northern Africa, with the local grey insertions of volcanic lava and copper-coloured sands of Kalahari desert in the south, and in-between all these the compact dark green area of equatorial forests, in the region of Congo River.
The African continent with an area of about 30 mill. km2 is the second largest after Asia (representing approx. 20% of the world’s land surface) and the only one stretching in the equatorial zone into both tropical areas of the northern and southern hemispheres. Sahara wasteland, with its southern part named Sahel is the greatest world desert with an area of 7.77 mill. km2 and, together with the Libyan desert of 1.68 mill. km2- actually an extension of Sahara, totals about 9.5 mill. km2, covering almost 30% of Africa’s surface. Such unproductive lands unsuitable for agriculture represent between 40% to 90% of the area of circum-Saharan countries, thus impacting their economy to a great extent.
Africa is a land belonging to the Earth’s most ancient geological era (Precambrian) that at more recent dates was pierced in certain areas by volcanic lava insertions, reaching here and there to 180 thick. After the subsequent tectonic moves, the highly cracked African crust provides the greatest land sinking of Terra, beginning with the Dead Sea, going along Nile’s upper course and in the area of the great lakes Albert, Tanganyika and Nyassa. The regions of Ethiopia, Kenya, Tanzania and Mozambique are going to get separated from Africa and become islands in time, such as Madagascar today (Fig. 2).
The mountains of Central Africa
In general the current landforms of northern Africa consist to a great extent of plateaus between 580-760 m high, with two concentric mountain rings (lake the water waves after throwing a stone). The first string of heights consists of Mounts Atlas in the northwest with summits of over 4,000 m, whose continuation can be found- with some interruptions because of sinking in the bed of the Mediterranean Sea- through Sicily, Peloponnesus and Mt. Taurus in Asia Minor, and further on into the heights of over 3,000 m bordering the Red Sea shores. To the south are the Ethiopian mountains and those of Uganda and Kenya, with summits of more than 5,000 m, being continued with over 2,500 m high peaks in Cameroon and Nigeria, delimiting the hydrological basin of Congo River to the south, and ending with Mt. Fouta Djallon of over 2,000 m high that accompanies the northern coast of Guinea Gulf along almost 1,000 km between Senegal and Liberia.
Inside such first mountain ring is the second one, consisting of Mt. Aïr of Niger with over 2,000 m high summits and of massif Ahaggar of Algeria, whose peaks exceed 3,000 m (peak Tahat- 3,003 m) and Mt. Tibesti of Chad reaching to 3,415 m with summit Emi Koussi; further on with Mt. Marra between Chad and Sudan, with peaks exceeding 3,000 m (Fig. 3). This second mountainous round outline bordered by high plateaus to its outside comprises within an almost closed basin, with no possible outflow of water from rare precipitation.
In time, precipitation water flows have silted through alluvia the bottom of this basin, generating either temporarily swampy areas during rainy intervals or deserts during the dry season, allowing winds to carry away the sand and to build up travelling dunes. It is again the flowing of precipitation water that reduced the water drain slope, leaving behind vast plane lands with scattered boulder stones which could not be carried away by water, consequently these areas have been called ergs. Such a region, named Great Erg Ténéré is found northeast of Mt. Aïr in Niger, while in Algeria there are the Great Western Erg and the Great Eastern one. The regions with ergs and sand dunes cover however only a tenth of Sahara’s area, the remaining part consisting of rocky mountains and high barren plateaus, with relief modelled by the great temperature differences between night and day, by winds and water, ergs providing very few oases.
The waters of Central Africa
The great rivers of Africa- the Nile, Congo and Zambezi getting their water from wet equatorial regions- although providing high flow rates do not facilitate the navigation of big boats because of the rock thresholds (waterfalls) and cascades along their course. The closest river of northern sub-Sahara is Niger, springing from the feet of Mt. Loma and having got its water from the Atlantic-blown clouds. Such precipitation having fallen on the southern side of Mt. Fouta Djallon has met wide slopes, thus generating tempestuous torrents of short course; but the precipitation falling on the northern slope of such mountains gathers and thus issues the great Niger River whose course turns northeast, towards Sahara. Niger River floods a plane area, changing it into a large swamp (also called ‘inner delta’) between the towns of Timbuktu and Kabara, and its water changes course to southeast only when it has passed through Tosaye strait.
On its right bank Niger receives important tributaries like Milo, Baoulé, Bagoé and Banifing, together shaping the great river Bani and the it takes rivers Sirba, Atakora and Oli. Rivers Kebbi, Sokoto, Kaduna and Benoué gather from Niger’s left bank, eventually discharging its annual average flow of about 14,000 m3/s (doubled during the rainy season) into the Atlantic Ocean by means of a huge delta (Fig. 4).
A well-defined complex system of valleys called oueds, usually devoid of water, is distinguished in the central part of Sahara. Such valleys direct the precipitation water from massif Ahaggar, plateau Tassili-n-Ajjer (‘plateau of waters’ in local language) and Mt. Aïr either to Lake Chad through oueds Amadra, Admer and Tafassasset or to Niger’s bed through oueds Tamanrasset, Tilemsi, Timersat and Tessalamane.
The climate and vegetation of Central Africa
The climate of northern and central African regions is nowadays extremely dry, average annual precipitation recording less than 25 mm water column, which however evaporates almost 90% before getting into the earth (Fig. 5). Natural vegetation is little developed, here being found large areas with scarce trees and thorn bushes, while in other zones there is absolutely no vegetation at all (Fig. 6).
The water needed for inhabitants is often brought from non-potable sources with high risk of illnesses, and the absence of rich water sources forbids a satisfactory agriculture to develop, thus mass emigrations of inhabitants towards wetter regions taking place during very dry years or consecutive dry ones. Agricultural activities are performed upon small land areas with rudimentary means- cattle-drawn plough, manure as fertiliser. Pastures being absent, cattle feed on weeds and straw and therefore their milk yield is minimum. A Mauritanian woman (Fig. 7) uses a teapot to water a few small vegetables she planted near the tent, which she surrounded by thick cloth as protection against wind-blown sands that are a great threat to agricultural crops (Fig. 8).
Saharan desertification is currently in full process. If in 1930 Lake Chad in the middle of Sahara provided during the dry / wet seasons an area between 10,000 and 25,000 km2 and its waters were 7 m deep, at present its surface has been reduced almost 12 times (Fig. 9).
Africa’s demography and economy
The absence of water will turn severe in Africa in the following years because of its rapid demographic growth. The annual growth of African birth rate is almost 5%, one of the highest in the world, an African woman bearing 5 children in the average during her lifetime. In colonial years (1850) Africa’s population was estimated to 100 mill. inhabitants, while in 1950 it had grown to 220 million and it reached 900 million in 2000, with estimations providing over two billion Africans in 2050- one of the most populated continents.
Given the difficult living conditions, inefficient agriculture and absence of jobs, at present a true exodus of populations takes place from rural areas to towns, generating the insalubrious ‘shantytowns’ as Africa’s urbanisation process is among the highest in the world (3.5% each year). Real mega cities developed with inhabitants exceeding 15 million (the population of Lagos city increased by 64% in the last years, reaching to 18.6 mill. inhabitants, while Cairo in Egypt has exceeded 17 mill.). Under such circumstances, huge burdens are involved for the good administration of cities in terms of living areas, road network and means of transport, utilities and hygiene for inhabitants, environmental pollution etc.
The fast demographic growth rate makes Africa the continent with the youngest population (young people under 21 make about 71% of the whole population), however mention should be made that the first death cause in Africa is AIDS. The absence of jobs makes 66% of African population dependent on survival agriculture, which in view of the ‘demographic boost’ will require vast land areas good for intensive cultures, and therefore large amounts of water.
As far as sub-Saharan countries are concerned, current statistics show an even worrisome situation:
- Infant death rate (until 12 months) is of 102 / 1,000 babies
- Average living expectations are of 46 years
- The population in rural areas have got treated water covering only 45% of their needs
The average income of 50% of the Africans is of 1 USD/capita/day. It is only 10 from the current African states that record a GDP of about 3,500 USD/capita. (Chad has got a GDP of only 1,600 USD/capita). The networks of modern roads and railroads are the smallest in size in Africa. The electricity consumption of all African countries is only 3% of such consumption in the world. Ten of present-day African states have got no outlet to the sea, which is a great handicap to their trade.
The African sub-soil has got oil, gas, coal, uranium, gold, diamond etc. deposits that bring important revenues from trade, but unfortunately the money does not go wherever it is most needed by Africans. At present 38% of the 35 million oil barrels daily extracted in Africa go to Canada and the USA, 35% to Asia and Pacific countries, 20% to Europe, 5% to Latin America and only 2% are used by Africa.
The absence of schools (2,000 languages are spoken there) is a vivid absence in Africa, which prevents the inhabitants to provide qualified work, but in exchange the stock of fire arms in sub-Saharan states is of about 30 million pieces. Under such circumstances, Africa urgently needs a major financial aid if no explosive economic situation is desired at world level, which will no longer be held under control.
