The Senegal River report, by Anke van Harteveld
Characteristics
Length: 1641 km
Drain-area: 450000 km2
Temperatures: between 17 and 41 degrees celcius
Rainfall: from 250 to 750 mm per year
Environmental problem
- Disadvantages of building dams for irrigation
Conclusion
Eventuall the conclusion can be drawn that the benefits of the dams do not outweigh the disadvantages yet. This will change when the Manantali electricity project becomes a success and the switch to irrigated agriculture has been made. When a solution is found for the spreading of diseases trough stagnant water the conclusion can be drawn that the construction of the dams has been successful.
Abstract
Facts of the river Senegal The Senegal River is a river that rises from the Fouta Djallon plateau of Guinea. It flows to the northwest through Mali and from there west to the Atlantic Ocean, forming the border between Mauritania in het north and Senegal in the south. The river is 1641 kilometers long and the river basin is 450.000 square kilometers wide. The morst important function of the Senegal River is water supply. Furthermore it is used for fishing, shipping and recreation.
Of the various headstreams of the river, the Falame, Bafing and Bakoye are the most important. The Falame and Bafing rivers rise in the sandstones of the Fouta Djallon plateau in Guinea, while the Bakoye rises in western Mali. The Bafing and Bakoye meet at Bafoulabe in Mali to form the Senegal. The stream is than joined by the Falame, near Bakel, Senegal. From there onward the Senegal-Mauritania border lies on the right (northern) bank, so the river belongs to Senegal; Maurtiania, however, has been permitted to use the river.
Below Danaga, at Richard-Toll, the Senegal enters it’s delta. The river’s gradient is extremely slight in the delta, and, until the competion of the Diama Dam near the rivers mouth in 1985, salt water was able to flow upstream to Danaga during periods of low water. The mouth of the Senegal has been deflected southward by the offshore Canary Current and by trade winds blowing from the north; the result has been the formation of a long sandpit, the Barbary Tongue (Langue de Barbarie).
The Bafing and Falame sources receive about 2.000 millimters of rainfall annually, mostly from late March to early November; the Bakoye basin recieves less. The Senegal River Valley proper recieves 250 to 750 millimeters of rain anually, from late May to mid Ocober, with mean maximum temperatures of about 410C in April, and mean minimum temperatures of about 170C in January. Rainfall diminishes downstream.
Typical trees of the Senegal River Valley are Acacias, notably Acacia nilotica, wich grows profusely on banks, and A. senegal, wich provides the gum arabic of commerce and grows on drier slopes. The grass Vetiveria nigritania grows in tufts in wet depressions. In dry areas near the valley side’s A. albida, Balanites aegyptiaca and grasses are common. The river is over fished, but Nile perch are common. Spoonbills, herons, egrets, and weaverbirds are widespread. Among the animals on the riverbanks hedgehogs, monitor lizards, and wardhogs are fairley common. The Senegal River Valley below Danaga is populated by the Tukulor (Tokolor), after which Soninke (Serahuli) dominate. Villages average about 300 people exept in the delta, which is sparseley settled. Troughout the Senegal River Valley region small groups of usually nomadic Fulani (Fulbe or Peul) and Mauri (Maure or Moors) are found.
The river basin of the Senegal River
The 1972 ‘The Organisation for the Development of the river Senegal’ (Organisation pour la Mise en Valuer de Fleuve Senegal—OMVS) was founded. It is a cooperation of tree of the four countries in the Senegal River Basin, Senegal, Mauritania and Mali. Guinea is welcome to join, but has not repield yet. The OMVS has constructed dams, the Manantali and the Diama dam, in the Senegal River. The functions of the Manantali dam are irrigation and hydro-electricity. The functions of the Diama dam are to prevent slat water from entering the river and irrigation. In addition to these functions the dams are to establish a constant water level in the river which will benefit shipping and fishing.
When flooding agriculture is compared to irrigated agriculture it is obvious that irrigated agriculture is more productive. However, when workforce and investments are taken into account, irrigated agriculture is less benefitting than it seems. Alltough the dams will eventuall give a more constant supply of food, the dams are bad for public health. The dmas contribute to water-born diseases via irrigation canals and water-storage areas. The stagnant water is source of infections.
Links:
http://www.fao.org/waicent/faoinfo/agricult/agl/aglw/aquastat/maurita.htm
http://www.odci.gov/cia/publications/factbook/geos/mr.html
http://pasture.ecn.purdue.edu/~abe325/present/sld150.htm
http://lcweb2.loc.gov/frd/cs/mrtoc.html
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