African Unification Front
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WATER RESOURCES IN THE NORTHERN INTERIOR
An oasis in the Sahara desert (Northern Interior)
Africa's Northern Interior consists of Morocco, Western Sahara, Mauritania, Mali, Algeria, Tunisia, Niger, Libya, Chad, Sudan, and Egypt. The Northern Interior [Sahara] averages less than five inches of rain each year. The North Interior, which corresponds to the Sahara Desert, occupies almost 20% of the African continent. It extends from Morocco in the west to Egypt in the east. The largest part is occupied by Algeria (33%) and Libya (25%). More than 80% of the area of each of these two countries is located in this region. The average annual rainfall is only 40 mm. It is 0 mm in Niger.
The North Interior is a tableland with an average elevation of 1300 to 1600 feet, with small patches of elevation as depressed as 500 feet. Even smaller areas (in Egypt and Algeria) descend below sea level (such as the Qattara Depression). In the Ahaggar and Tibesti massif, mountains climb from 6,000 to 11,200 feet. Notable peaks are the Tahat (9,852 ft.) and the Emi Koussi (11,204 ft.). Amid the sand and rock are oases with vegetation (date palms, acacias).
View of the Al Haggar mountains from the hermatage at Assekram
The topography of Western Sahara is made up of plains and some small plateaux that rarely reach 400 meters. The Western Sahara can be divided into three regions :
[1] The northeast zone from the chain of Atlas mountains to the hills of Zemmour is a rocky desert (hamadas) with steep mountains and a pro-nounced relief except for a few scattered wells.
[2] The second zone is made up of rivers. It includes the Wadi Draa to the north and the Jat to the west. These wadis are often depressions where water gathers during the brief rainy seasons, particularly in autumn. Because of the high temperatures the water quickly evaporated and never reaches the sea. In this river zone flows the Saguiat el-Hamra (the Red Canal) whose importance lends its name to the region. Sufficient vegetation for grazing grows along its banks and at Smara, barley and corn are cultivated.
[3] The third zone, the Rio de Oro, is inland and consists of flat plains, ergs and sand dunes. The ground is too permeable to retain the autumn waters and too flat to allow it to flow, hence water accumulates in the subsoil forming numerous wells. The inland landscape is quite monotonous and along the coast this monotony is only broken by the peninsulas of Dakhla (ex-Villa Cisneros) and Guera. Inland, the climate is continental with cold, dry winters while summers are extremely hot with temperatures reaching 60ƒ (in the shade) and the coastal humidity causing fog, mist and dew. Dakhla receives a yearly average rainfall of only 45 millimeters.
On the coast, vegetation and flora is abundant due to the humidity. Inland, one finds the typical flora of the steppe and desert; some locusts along the wadis and shrubs in the sandy depressions. To the south, there is little fauna and to the southeast, it is mainly fennecs, antelope and gerbils.
IRRIGATION POTENTIAL
The Great Artificial River, is a massive 25 year irrigation project expected to cost $25 billion. It was begun in 1984. It transports water from wells in southern Libya to the coast to irrigate about 74,870 hectares (about 185,000 acres) of land.
The renewable water resources in the Rheris and Guir basins in Morocco are estimated at 0.82 km3/year, of which 0.67 km3/year is surface water and 0.15 km3/year groundwater. Average rainfall is 30 mm/year in Mauritania and 70 mm/ year in Mali.
For Algeria water availability and needs for 2025 have been estimated by basin. About 1.683 km3 of the water in the sahara is considered to be fossil water.
Available renewable water resources in the North Interior in Tunisia are estimated at 0.20 km3/year, of which 0.15 km3 is surface water and 0.05 km3 groundwater. For the whole of Tunisia it is estimated at 2.8 km3/year (of which 2.1 km3 is surface water), which is about 80 % of the total internal renewable water resources, estimated at 3.52 km3/ year.
Rainfall in the North Interior in Niger, occupying less than 1 % of the country, is negligible. Average annual rainfall is 10 mm in Libya, 45 mm in Chad, 105 mm in Sudan and 15 mm in Egypt. The irrigation potential for Mauritania and Mali using renewable water resources is negligible.
At present the irrigation water use of Morocco is 13375 m3/ha per year, in 2020 the country estimates its water use for irrigation to be 10380 m3/ha per year. Water requirements for Morocco range from 7000 m3/ha per year in the north to 15000 m3/ha per year in the south. The irrigation potential has been estimated at 60000 ha. Should 15000 m3/ha per year of water be used in the North Interior, the annual water use would exceed the water available, and the area should be reduced to 40000 ha at most.
In Algeria the irrigation water requirement has been estimated at 7000 m3/ha per year. There is an irrigation water requirement of 12000 m /ha per year for the northern part of the basin, where irrigation schemes would possibly be situated. The irrigation potential using renewable water ranges from a minimum of 20000 ha, considering a water use of 12000 m3/ha per year and a water availability of 0.240 km3/year, to a maximum of 125200 ha, considering a water use of 7000 m3/ha per year and a water availability of 0.876 km3/year.
The low estimate on water availability is based on the assumption that where the total water balance is negative this quantity is deducted from the water available for irrigation. The planned use of 1.627 km /year of fossil water for irrigation in 2025 would lead to irrigation of 135,600 if using 12000 m /ha per year of water and 232,450 ha if using 7000 m3/ha per year of water.
The irrigation potential for the whole of Tunisia has been estimated at 563,000 ha, of which 40,000 ha in the North Interior. With an irrigation water requirement of 14500 m3/ha per year of water, the total water requirement would be 0.58 km /year, which greatly exceeds the total available water resources, estimated at 0.20 km3/year. Reducing the area to 11000 ha means 0.16 km3/year of water would be required. The 40000 ha could only be irrigated by a water use of 4000 m3/ha per year.
As there is no rainfall in the North Interior part located in Niger, there is no potential for irrigation from renewable water resources.
The renewable water resources of the whole of Libya are estimated at 0.6 km3/year. As at present the agricultural water consumption is already 4.275 km3/year, most of it is fossil water [131]. It is planned to use an additional 2.365 km /year by 2025, bringing the total to 6.640 km3/year. The irrigable land has been evaluated at 750000 ha. Estimating 250000 ha to be located in the North Interior would require 2.225 km3/year of water if using of 8900 m3/ha per year of water. Taking an irrigation water requirement of 18000 m3/ha per year would lead to a total irrigation water requirement of 4.500 km3/year, all fossil water.
The oases in Chad are estimated to cover in total 100,000 ha. It is not clear what water would be used to irrigate these 100,000 ha, but probably most will be fossil water. It is estimated there are 10,000 ha located in the North Interior. The area in Sudan is also estimated at 10000 ha, in Egypt 50000 ha, all dependent mainly on fossil water.
Depending on the irrigation water requirements, estimates of the irrigation potential in the North Interior, based on renewable water resources, range from 71,000 ha to 225,200 ha.
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