Dahomey Gap

The Dahomey Gap ( also Dahomey Corridor ) is a dry zone on the Guinea coast of West Africa, extending from Southeast and Central Benin Togo to Western Nigeria. It is adjacent to a coastal dry zone in the region of Ghana and Togo (Ghana Dry Zone ) and forms an almost forest-free savanna corridor, which is embedded lying between the west and east of it evergreen tropical rain forests ( the English word "gap " means " gap", Dahomey is the former name of Benin). The rainforests west of the corridor are referred to as Upper Guinean Forests, those east of it as Lower Guinean Forests.

Climate and Reasons of the drought

Accra, lying in the subsequent drying zone of Ghana, receives an average annual rainfall of less than 800 mm (although as the northeast subsequent Dahomey Gap is part of the sphere of influence of the West African monsoon ), about twice that would be required at this latitude for a tropical rain forest. Also, the precipitation in the Dahomey Gap ( about 1100 to 1200 mm ) is not sufficient because of high evaporation from it.

With the emergence of this dry zone a complex interplay of oceanographic and atmospheric factors acting together. So drop in August, the sea - surface temperatures in parts of the northern Gulf of Guinea about 28 ° C to 21.5 ° C.. Intumescent cold deep water stabilizes the lower troposphere and thus reduces the amount of precipitation. This has a corresponding effect on the energy inland migratory squall lines. For the appearance of the cold deep water at the sea surface is a part of the prevailing southwesterly monsoonal wind direction responsible. However, plays a special role in an emerging equatorial Atlantic cold Kelvin wave incident on the shelf off the dry region. Some influence also has the orography: So the almost 1000 m reached the Togo Mountains meshes some of the moisture from the monsoon winds. Also the expression of the high-altitude wind field in the region of Dahomey Gap promotes here less convection than in the adjacent wetlands.

History and Significance

In its current ( vegetation ) form the Dahomey Gap exists, such as pollen analysis showed only about 4,000 years. In earlier phases of the Holocene, especially during the interglacial periods, and the precipitate was enough, however, from time to time, to close the gap by forest. The path ( savannah or a forest - savanna mosaic, among other things, rich in oil palm ) today acts as a natural barrier for the exchange of species of animals and plants between the west and east of it nearby forest areas.

Anthropogenic causes are not responsible for the training of the corridor. Their relative dryness makes the region but in terms of water supply particularly vulnerable to human disturbance. Some useful plants of the sub-humid tropics are here under the aspect of the precipitate at its lower attachment limit.