1. General considerations

From very ancient times people had to be permanently concerned with providing the fundamental surviving conditions, respectively getting drinkable water and food daily. Meeting such conditions required adaptation of the following activities:

Getting potable water: People’s settlement either near rivers of permanent water or in areas with natural springs or not so deep aquifer layers
Getting daily food: Hunting, Shepherding, Agriculture

If getting potable water required conditions depending on the natural features of the respective region, with only sometimes short drainage channels or wells to be made, however in order to get food people had to also carry out some specific activities such as:

For hunting
· Chasing the game and its periodical migration, thus hunters had to be nomads
· Hunting is an activity requiring certain skills, as it might endanger the hunters’ life
· Victuals obtained by hunting could not be preserved so they had to be consumed in a short while

For shepherding (only when household grazing herbivores have been domesticated)
· Providing periodically new pastures by burning or tree cutting into shrubs or forests, shepherds being obliged to be nomads or semi-nomads, like the hunters
· Supervising the grazing cattle and guarding them during nighttimes, using enclosures against predators

For agriculture
· Fallowing the fields, planting and gathering the crops; people became sedentary while waiting for the crops to mature
· Rich crops of good years allowed gathering goods and developing trade

Statistic data show that the following land areas have to be available with a view to satisfy the food needs by capita:
- For hunting: about 100 ha / inhabitant
- For shepherding: about 10 ha / inhabitant
- For agriculture: about 1 ha / inhabitant

It thus follows that, from all activities able to provide food to the respective populations, agriculture required the lowest areas of available land. The idea is confirmed, since all peoples have developed to welfare only when they have started practicing agriculture. People’s richness relies in the first place on the gathering resulted from the cultivation of land. At present agriculture is increasingly intensive, constituting a basic activity in all countries of the world.
Since however the lands usable for agriculture are often limited by natural conditions, unproductive soils, deserts, marshy areas or cold climates that do not allow crops to mature, but also because of fast demographic growth, the possibility to acquire the daily bread becomes an ever worrisome issue. Under such circumstances it is of utmost importance to put to use the currently unproductive lands and to protect agriculture-favourable areas by maintaining and fertilising them.

The purpose of this study is to specify the solution required in order to recover the unproductive land areas in the region of Sahara- the greatest desert of the world, which impacts to a great extent the progress of central African countries, and to return them into the agricultural circuit.

2. Some characteristic features of Africa

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.

3. Sahara was inhabited

Africa is considered the cradle of humankind, because the remnant bones of a 1.5 million years old Australopithecus have been found in its centre on the shores of Lake Chad, as well as many carved stones. Rocks shaped to be used as grinding mills have been identified among erg boulders, which were utilised in order to grind edible plant seeds from picking (Fig. 10).

The expeditions of explorer H. Lhote in 1956-1957 identified and reproduced many rupestral drawings and paintings in Sahara, below the shelters under the sandstone rocks on plateau Tassili-n-Ajjer. These drawings have outlines that were incised into the rock and range from a few cm to 8 m, sometimes being painted with brown shades, red or white; they represent people usually with their arms away from their bodies, their legs exaggeratedly long compared to their arms, with feathers on their heads and leaves around their hips, next to water-loving animals such as buffaloes, hippopotamuses, elephants and other herbivores such as antelopes, giraffes, horses and dromedaries.

The discovery of carved stones and rock drawings means undoubted proof that Sahara had been inhabited by human communities. A diversified flora and fauna, as well as the dry river beds (oueds) make us understand that Sahara did not miss water. Researchers however have established that no sea was ever in Sahara in the proper sense of the word, but only small lakes and swamps in the depressions, with no leaking possibility.

African paintings when studied showed an original characteristic, with no influence or connection whatsoever to the rupestral ones in Europe. The first African drawings are more symbolical, but they certainly belong to a Negroid population; however more recent paintings are more realistic and show some Egyptian influence. European rupestral drawings are less expressive and feature state of facts that say too little about their authors, while the African ones show the habits and concerns of those inhabitants, the construction of their houses, cattle domesticating and breeding. Also the diversity of hunted or domesticated animals suggests the climatic conditions of those times as well as the stages of African desertification.

The study of Saharan rupestral drawings and paintings allowed their classification in terms of style, as well as their dating into the following characteristic intervals (Fig. 11):

• Period of ‘boubal’ - Realistic colourless drawings strongly carved into the rock. ‘Boubal’ was a buffalo with large horns, a species extinct around 7,000 BC (Fig. 12);
• Period of ‘round heads’ - This shows types of local people that were not all black, even white ones painted in red and wearing some sort of masks on their heads, adorned with feathers or with animal horns. These have been dated around 6,000 BC (Fig. 13);
• Bovid or grazing’ period - Women and children stand before the huts represented by round outlines. Men drove the cattle into enclosures towards which other horned animals were heading as well. Dated around 3,000 BC (Fig. 14);
• Period of the ‘horse’ - Such drawings show carts with two spoke wheels drawn by a pair of horses driven by a coachman. They betray the Egyptian influence; dated towards 1,200 BC (Fig. 15). The horse was introduced in Africa when Hyksos invaded Egypt (1650-1550 BC) and was used in the Egyptian army. The horse proves pastures could be found then in the Saharan region;
• Period of the ‘camel’ (actually the dromedary, camel with only one hump) - Such drawings were dated after 100 BC (Fig. 16). Saharan desertification having reached this stage, respectively no more pastures or water sources, the horse had to be replaced by camels that were better adapted to the difficult desert life;

Another proof of Saharan desertification comes with the lowering of water beds in the last centuries. Thus in Egypt, 3,300 km south-west of Alexandria, there is an oasis Bahariya in the middle of the desert where, after current research studies, a great necropolis was found from the time of Lagyde pharaohs (around 300 BC), which allows believing in an oasis of over 10,000 inhabitants in those times. The necropolis has got mummies of local people placed in rock excavations, but never deeper than 2.5 m, which allows us thinking that around 3 m deep the water-bearing layers could have been found at that time, therefore these had to be avoided for a good preservation of mummies. Recent studies however have ascertained there aquifer layers about 14 m deep at present. Many other elements prove the worrisome desertification of Sahara and the need of measures to put an end to this process.

4. Water for Sahara

With such convincing proofs that Sahara had had water in the past, the researchers’ desire to know the reasons of climatic changes in this region is only natural. The attempt to find similarities between the Saharan climate and that of India is however fully unconvincing. In India there is a cyclic process determined by winds (monsoon) that carry the clouds from the northern Indian Ocean to the slopes of Himalaya Mt. where they discharge their precipitation, and then the waters flow down into India’s great rivers and after that- back into the ocean. The particular landforms in Africa and the distance between Sahara and the ocean exclude any resemblance between the climates of these two regions. The cause of climatic changes in Sahara must be searched elsewhere!

Getting water by pumping for agriculture from aquifer layers is not a proper solution, because their level goes deeper and deeper or even worse, as it has recently happened in Algeria. Extracting water from the first aquifer level, then from the second one and after that from the third, such water used at ground level has turned into waste water to a great extent (mixed with chemical fertilisers or with industrial pollutants, domestic waters etc.) but it was not treated and was disposed of into the desert at about 14,000 m3/day. Such water seeped into the first aquifer layer, but could not pass through to the deeper ones because of some intermediate impervious clay beds, so it raised the level of the first water-bearing layer and resulted into large-scale damage to the palm tree cultures practiced into unfriendly very wet soils.

The situation of the countries bordering the Mediterranean Sea, namely Algeria, Tunis and Libya is not better, as they also depend on water obtained from deep aquifer layers. In this respect the underground water reserves that are common to these countries acquire a strategic significance for their economic development, a little like the situation of oil deposits, since to extract and use such water they had to conclude strict trilateral agreements. There were 8,800 wells in the 1980s in the fore-mentioned countries, extracting huge water amounts for agriculture, while precipitation water represented only 0.0017% of the consumed quantity. Consequently, the current level of water-bearing beds is about 30 m deep, but it continues to drop. When such level reaches to approx. 400 m deep, the pumping system will no longer be economical and agricultural crops will have to be watered from other sources. At present various international organisations are striving to impose a balanced utilisation of underground water reserves, but in case of an acute water shortage if successive droughty years occur conflicts might arise that are difficult to control. From the above it clearly follows that in circum-Saharan states of northern Africa water drawn from underground aquifer layers is not a long term solution and another water source has to be found, but which one?

Studying the physical map of northern Africa, one can notice that Niger River, gathering its waters from the northern slopes of Mt. Fouta Djallon directs its course towards central Sahara; however a little downstream of Timbuktu it turns 90o southwards and the good running water of Niger River provided free of charge by nature is lost without a rational utilisation, flowing into the Atlantic Ocean. One can also see that the inner ring of mountains in Central Sahara enclosing Lake Chad within has got a single breaking point towards the west. The coincidence of such physical details at present cannot be overlooked, as it allows explaining the change of Niger River’s course by major geological events in the area in past millennia.

When it has detached itself from the great pre-Cambrian land, with the future African block at its centre and many territories as well whose movement in time has led to the current layout of continents, Africa underwent multiple changes, namely outflows of volcanic rocks and many deep cracks in its earth crust (Fig. 17). One of these faults oriented N-S is perpendicular to the initial course of Niger River and its waters, captured along such fault, change their flowing direction southwards; similar situations are found along other water courses as well, such as Zambezi River, at Niagara Falls, Nile River etc. (Fig. 18). The map of Africa (see Fig. 3) also shows a river bed that is currently dry (oued), outlining the initial course of Niger River that connects to central Sahara. Joining such indications to the dating of rupestral drawings, one can reconstitute that Niger River has had a continuous W-E course about 10,000-8,000 years ago, taking its waters to Lake Chad- a relict of this river which maintains a high level of aquifer layers in the region and thus allows pastures, fauna and local human communities to be found there.

Researchers arrived at the conclusion that around 8,000 years ago Sahara’s vegetation was satisfactory for regional fauna, providing rich game to the locals (period of ‘boubal’, around 7,000 BC) and harvesting of savage grains (period of ‘round heads’, around 6,000 BC). Strong movements of the African crust occurred at that time, generating the fault that deviated the course of Niger River. Saharan vegetation began missing water, and the initial savannah, once household herbivores (cattle, sheep, goat) were domesticated, changed into vast grassy lands good for grazing (‘bovid or grazing’ period, about 5,000 BC).

During this era around 3,500 BC a great migration of local population took place because of the difficult survival conditions in Sahara. Moving south and being blocked by exuberant equatorial forests, the only migrating options remained to settle north on the shores of the Mediterranean Sea and along the course of Nile River. This is the only possible explanation for the great mix of people in Egypt of various nationalities, habits and religions who finally learned to live together peacefully only because of their interest to jointly manage Nile’s waters for agriculture and navigation. It is still in this era that the first dynasties of Egyptian pharaohs came into being that, in view of unifying religious creeds, also introduced the god with ram head (symbol of Amon), which was finally accepted by the people however keeping their local deities as well. The horse introduced by Hyksos in Egypt and later on in Sahara (period of the ‘horse’, after 1250 BC) could be used for some time towards the beginning of our era when, water running scarce and pastures shrinking, it was replaced with the dromedary (period of the ‘camel’, towards 100 BC), much more adapted to the new circumstances within the region.

This is actually the cause of Saharan desertification - the transversal fault across the course of Niger River, and the measures proposed in this study lead just to ‘correcting’ nature and restoring the initial configuration.

5. Solutions; Proposals; Estimated results

As also shown previously, the increase of living standards for the inhabitants of circum-Saharan states relies first of all on using their own territories that are deserts now, with a view to practicing there an intensive agriculture. This study on the Sahara desert aims at reaching the following goals:
- Getting the water required for agricultural crops
- Stopping Saharan desertification and bringing the reclaimed land back into the countries’ economic circuit
- Practicing an intensive agriculture with minimum water consumption
With a view to achieving such goals, mention should be made that about 80% of the water consumption in the world goes to agriculture at present. Further on are the solutions and main proposals of the study.

a. Water source
The water needed for future agricultural crops in the Saharan region can be obtained without permanent costs to procure it, as it comes directly from nature, and aquifer layers are not impacted in the least. Such water can be taken from Niger River under an annual programme, in variable amounts depending on its flow rates during the dry / wet seasons, since findings show that the water flows of this river, ranging from 15,000 m3/s to 30,000 m3/s, when all the water needs of all Niger riverside states are covered, run unused into the ocean.
It is likely that, when agricultural cultures in Sahara have been made, the flow rate of Niger River will be lower at its ocean flowing than the sum of flow rates of all its tributaries. This fact was also ascertained for the Nile River in Egypt, because of the irrigation of great land areas now cultivated. (The annual average flow rate of Nile waters upon entering Lake Nasser of Aswan is of 3,800 m3/s, while in Cairo upon flowing into the Mediterranean it is only of 2,300 m3/s, respectively 60% of its received amount).

b. Water intake
Water from Niger River will probably be taken on the territory of Niger state, between Timbuktu and Niamey. The solutions that can be taken into consideration in order to make Niger waters cross the tectonic fault eastward are as follows:
- By siphoning using U-shaped pressurised pipes
- By pumping using vault-shaped pressurised pipes
- By a water bridge
The first two solutions utilise current techniques applied in the construction of hydropower plants. The last one has been used in Hamburg harbour, Germany. However the solution will be determined using proper technical-economic calculations. The developments for the water intake will be able to solve also the upstream basin of Niger River by systematising the current swampy insalubrious region, also called Niger River’s ‘inner delta’.

c. Bringing the water into Lake Chad
Once the water has been taken over and crossed eastward over the tectonic fault, it can reach Lake Chad either by means of conduits meant to avoid losses by evaporation or using an open channel, or even by mixing these two solutions. Given that some changes in the relief of the area might have occurred in past millennia since the fault has occurred, additional work could be required in order to provide water flowing along the natural slope towards the depression where Lake Chad is found, possibly even intermediate water pumping stations. Such work is however habitual in this field. The map in Figure 3 provides the dotted outline of a OUED course (dry basin of a river) from west eastward, showing also that at half distance to Lake Chad (near Zinder) the water might reach its destination using the course of river Komandugu.

d. Lake Chad, a buffer water reservoir
Lake Chad will be a compensation reservoir for the water taken over from Niger River during the dry/wet seasons. Since it has been greatly silted in time by alluvia carried by torrents from the area, its storage capacity will have to be enhanced however not by increasing its surface but by deepening it, thus reducing losses through evaporation. The un-silting of Lake Chad will be scheduled depending on the amount of water provided to be stored temporarily, in accordance with the operational regimes adopted.

e. Increased water efficiency by irrigation
As regards water utilisation for agricultural activities in the desert, the water saving for various cultures requires irrigation. This can be performed by conventional aspersion (Fig. 19), or using a mobile drum and hose (Fig. 20); however the most efficient moisturising method is by dripping (Fig. 21), which is good for all types of agricultural crops (pastures, cereal crops, vegetables, vineyards, orchards, flower growing etc.).
Depending on the specific culture, wetting by dripping can be performed in several variants:
Dripping system
Water flow rate by dripping device
Life cycle of material
Cylindrical dripping device
2.0 litres / hour
8 – 10 years
Flat dripping device
1.65 l/h
4 – 5 years
Band dripping device
1.0 l/h
3 – 4 years
Irrigations by dripping provide many benefits, among which the following:
- They allow watering the plants and fertilising them at the same time (fertilisers are added to water)
- They require a low water consumption (about 60% against the traditional irrigation system)
- They use water at reduced operational pressures
- They require a low power consumption
- They allow automating the process
- They provide the greatest continuity in wetting the cultures and their perfect location
- They facilitate water penetration even in highly impervious soils
- Water distribution into cultures is independent on the wind downsides
- They delimit the proliferation of pests
- They can be performed on uneven or bumpy grounds
- They do not require qualifying the operational personnel
- They allow personnel and annex outfits to move between rows, even during wetting
- They require low costs for water distribution pipes, as their operational life is long
Various wetting systems by dripping are illustrated for fruit-bearing orchards in Malta (Fig. 22), for stalk cultures in Jordan (Fig. 23) and for pastures in Libya (Fig. 24).

f. Estimated results
The performance of the work provided in this study will bring huge benefits in many fields for all circum-Saharan states, but perhaps for other African countries as well; among such benefits, mention should be made of environmental protection since the impact is positive; sensible economic growth, and even favourable political images. Thus we can provide such examples:
- Limiting the desertification of lands and bringing them back into the economic circuit
- Increasing agricultural productivity by extending cultivable areas and stabilising sandy grounds
- Getting natural inexhaustible water with minimum operational costs
- Reducing the environmental impact since aquifer beds are not depleted, but on the contrary supplied
- Improving and diversifying the food sources for inhabitants, as well as their cattle stock that will become more productive
- Stimulating domestic and foreign trade
- Utilisation of local labour and reduction of unemployment
- A great number of inhabitants will become sedentary
- Reduced emigration to other countries
- Enhancing the renown of the Organisation for African Unity in the world

6. Final considerations

The studies and execution projects required for the work provided in this paper have to be grounded on certain data that can be obtained only in close cooperation with the competent local authorities. Such studies mean topometric, geologic, climatologic, hydro-technical and hydropower work; the type and specificity of agricultural cultures to be obtained; water utilisation management; irrigation systems etc. It is only when all these data have been obtained that the costs and term of execution can be determined. However mention should be made that all work provided under the project of water supply to Sahara and desert lands fertilisation can be carried out using present-day techniques and technologies.

The possibility and extent of work needed to fertilise the desert regions of Sahara can be exemplified by Egypt. Since 1997 upon the initiative of President Mubarak they provided building a complex canal network, 320 km long, by means of which about 25 mill. m3 of water are extracted daily from Lake Nasser using 21 huge pumps, thus irrigating about 200,000 ha of agricultural crops. The same source has been used in order to provide water over long distances to the oases from the hot and completely waterless Libyan desert. After all, what has been realised in Egypt by taking over water from the Nile, accumulating it and then pumping it to ploughed fields is an initiative similar to what is proposed in this study, however using the much richer water flow of Niger River.

Since the ensemble of work provided impacts several circum-Saharan states, a preliminary consensus is required among the governments of such countries, specifying the responsibilities and obligations of each participating party, while also determining the water flow rates taken from Niger River all year long without prejudicing the water needs of all Niger riparian countries for agriculture, industry, navigation, hydropower work and social needs.

The amount of work provided under this study exceeds the financial capabilities of interested African states, therefore a clairvoyant decision of humanity is required so that developed countries can provide the logistics and financing of such projects, which otherwise also serve the interest of these countries by reducing the mass emigration of Africans; such a process would be difficult to keep under control in future years given the demographic explosion of autochthonous populations, which would simply disorganise developed states.
Similar statements can be found in the 1997 Report of the European organisation EAWAG, of which we quote: “Water availability in northern Africa will significantly reduce in the following years. Without taking serious measures, the inhabitants of this area will have an only option- their emigration northward. It is in the interest of European states to solve the water problem for such populations, together with the African states.”

Official organisations and institutions were established in certain African countries in previous years, which can provide a proper legal framework for the work proposed here. Thus several meetings were held in order to coordinate and facilitate the initiatives supporting African states. Among the most important ones mention can be made of the following:

• An Office for Niger was set up in 1970 within the Francophone Organisation, under which irrigation projects were developed for cultures in Mali and a hydropower plant was built on Niger River.
• The 1962 meeting in Lagos, Nigeria was transferred next year to Addis-Ababa in Ethiopia, when the Organisation for African Unity was established and its first reunion took place in Cairo in 1964, during which a judicial Agreement was concluded between African states.
• The meeting of November 25th, 1964 at Niamey, Niger saw the establishment of the Niger River Committee- an inter-African organisation consisting of 9 riparian states to Niger River and to its tributaries: Guinea, Mali, Niger, Benin, Republic of Nigeria, Ivory Coast, Burkina Faso, Chad and Cameroon. The Agreement regarding the Niger River Committee, the navigation and transportation on Niger River was signed then.
• At present scientific institutions of Germany, France and Switzerland sustain the activities of the organisations Observatoire du Sahara et du Sahel (OSS) and those of the Organisation for African Unity, and international organisations (IFAD, GEF) have been participating as well since 1996.