Sahel

The Sahel, which is sometimes also called the Sahel only is the in Africa elongated semi-arid transition zone from the actual, subsequent to the north of the Sahara desert area to dry or moist savannah in the south.

In this area there are usually at intervals of just a few years severe droughts leading to famine. However, in 2007, floods in many parts of the Sahel, the millions of people homeless.

  • 4.1 Agriculture
  • 4.2 livestock
  • 6.1 Main rivers
  • 6.2 Other rivers
  • 6.3 lakes

Name interpretation

ساحل / Sahil is called in Arabic shore or coast and refers to the fact that the sparse vegetation of the Sahel found the Sahara who cross the coast of the sea of ​​sand and that migrated through the desert nomads see the Sahel with its lush vegetation as bank or seen have.

Geography

Location and extent

While sometimes only the more western African countries are counted for the Sahel, most scientists and researchers refer to meteorological and vegetation geographic base usually the elongated and rather broad belt from the Atlantic to the Red Sea and an adjoining narrow strip to the Indian Ocean as the Sahel. If you measure it, the route from Dakar (Senegal) on the Chad basin to the Red Sea (Eritrea), we arrive at about 6,000 km in length - more to the Horn of Africa (Somalia), there are a total of 7,500 km in length. Here, the area includes a strip having a width of 150 km (in the east in the area of the Red Sea ) to 800 km (in the west at Dakar ), with increases the desert in southern direction annually by 7-10 km.

There are thus seen from west to east these states, many of which are among the poorest in the world, in the Sahel, or they have it ( what part of the country is one of the states share the Sahel, is, inter alia, by the additions north, south, middle, West or East in ):

  • Senegal - North
  • Mauritania - South
  • Mali - center
  • Burkina Faso - North
  • Niger - southern middle
  • Nigeria - extreme north Also Nigeria is counted for the Sahel, but this applies only for the far north, because the majority of the land of wet savannas and its south is occupied by rainforests.
  • Regarding Ethiopia, many people are of the opinion that the entire country is counted for the Sahel, but this is a fallacy (see below Subsequent natural areas ).

Landscape

The Sahel consists mainly of thorn savannah. From north to south, the belt is divided into these biomes on:

  • Desert and semi-desert
  • Thorn, grass and shrub savannah
  • Dry savannah

Subsequent natural areas

In western and central Africa, the Sahel extends north in particular the aforementioned Sahara from; south of this belt is followed mainly in the briar and Sukkulentensavanne, which in turn further south, then only passes in the dry savannah in the humid savanna, which is followed by the Tropical Rain Forest.

In East Africa - in the area of often plagued by drought in Ethiopia - closes north of the Sahel and the Sahara mostly on if the country is not already on the Red Sea ( in Eritrea) and the Gulf of Aden ( in Djibouti) encounters. There, close to the south of the Sahel both wet savannas and small rainforest -like areas, which are partly in the Ethiopian high mountains ( the highlands of Abyssinia ), to local island mountains and to high-lying lakes (especially Lake Tana ) spread. But increasingly disappear " oases " (or they are at least less ), so probably soon be more than just northern Ethiopia must be counted in the Sahel, which makes a northern arc to the highest elevations of the land in this country. At the Somali ocean coast, this zone also proceeds in semi-deserts.

Climate

To the north are hot and dry climate in the south partly humid and hot. In the Sahel, the low average annual precipitation falls from very different:

  • North - desert and semi-desert - per year to a maximum of 20 mm ( long-term average )
  • Mid - thorn, grass and shrub savannah - per year up to 100 mm
  • South - dry savannah - per year up to 500 mm, especially during the two - to four-month monsoon season (late June to September)

In the 1970s and early 1980s, these values ​​fell, so that the Sahara continues to spread in the direction of the Sahel (see desertification ). Mid-80s turned this trend, since taking the rainfall to. Compared to 1980, the Sahel is much greener today. Nevertheless, the AU has started the construction of a "green wall". On the other hand, it is observed that many species of the Sahel are always further south to meet in the Sudan zone.

The Sahel is located in the zone of tropical climate change, that is, it is a change of dry season and the rainy season instead. In the Sahel, however, this is by no means a regular change. Here clearly outweighs the drying time up to 10 arid months. Prolonged droughts alternate with only short periods of rain. The annual average temperature is about 20 ° C to obtain a high evaporation takes place in the territory of the Sahel.

Passat circulation and monsoon circulation play an important role in the Sahel.

In winter ( dry season), the Intertropical Convergence Zone (ITC ) shifted up to 25 ° south latitude. By compensating flows between the Azores high and the equatorial trough of low pressure caused NO trade-winds, which are called in the region of the Sahel Harmattan and bring drought in the winter months.

In the summer months ( rainy season), the ITC moved up to max. 18 ° north latitude, although it reaches this value only exceptionally rare. By compensating flows between the subtropical high pressure belt ( Azores high ), the inflow of cold deep currents in the Gulf of Guinea and the ITC make the West African monsoon arise that pass the Sahel. The West African monsoon is caused by the interaction of temperature and pressure gradients over the Atlantic Ocean and the continental Africa. The further the ITC then be shifted to the north, the more humid air masses can reach the Sahel. The irregular shift of ITC therefore come about the irregular rainfall. The Sahel zone is between 12 and 18 ° north latitude, that is, if the ITC moves, for example to 18 ° north latitude, fall rainfall throughout the Sahel. However, once the ITC migrates back to the equator, hiking and the moist air masses back (SO trade-winds ) and the Sahel is then completely dry because it will again flow through NO- trade-winds.

This phenomenon also explains the great desert, the Sahara, the north adjoins the Sahel. The equatorial trough of low pressure will never exceed the 18 ° north latitude, making the area between latitude and ending on the 30th degree of north latitude is happening throughout the year of NO - trade winds and thus there are no rainfall.

Economy

Agriculture

The farmers in the Sahel operate mainly millet cultivation. However, cassava, yams and sweet potatoes are grown for subsistence agriculture ( subsistence farming ). Over the years, they shifted their arable land because of the tremendous increase in population increasingly in the north, where they crossed the border and now a dry Agronomic irrigation is necessary. A common system for the restoration of degraded drylands and increasing soil fertility is the Zai. In several villages, an attempt is made to meet often with the help of aid agencies, the widespread malnutrition through horticulture in irrigation technology, but it is due to lack of water repeatedly to setbacks. Sustainability are very sophisticated systems of crop production that minimize the water demand.

Cattle breeding

The second important aspect of agriculture in the Sahel region is cattle breeding. People zoom in the course of massive population growth for their cattle and goat herds. In addition, their quantity is more important than quality. This leads to the fact that many animals eat the plants, including the root and the already hard, dry soil by the animals trampled and compacted. This reinforces the desertification of soils. In addition, the farmers featured on the basis of high rainfall periods, well construction and development aid pasture walks, which means that you no longer comigrating with the precipitate. All of these factors ultimately lead to a strong over-grazing, which plants because they are constantly eroded, no longer able to regenerate, the soil acidifies through the urine and feces of animals and more and more trees die, because the goats nibble at the bark.

Places

  • Dakar - the capital of Senegal
  • Nouakchott ( Nawakshut ) - capital of Mauritania
  • Bamako - capital of Mali
  • Gorom Gorom - - town in Burkina Faso
  • Niamey - Niger capital of the
  • Kano - city in Nigeria
  • N'Djamena - the capital of Chad
  • Khartoum - Capital of Sudan
  • Gondar - City in Ethiopia
  • Asmara - capital of Eritrea
  • Djibouti - capital of Djibouti
  • Berbera - city in northern Somalia
  • Timbuktu - city in Mali
  • Kaya - city in Burkina Faso

Waters

Main rivers

  • Niger ( stranger flow )
  • Shari
  • Nil ( stranger flow )

Other rivers

  • White Volta
  • Black Volta
  • Komadugo
  • Salamat
  • Sokoto
  • Bani
  • Chari
  • Logone
  • Benue

Lakes

Semi-arid climate Tropical rainforest High Alps Monadnock Desert climate Gorom-Gorom Kaya (Burkina Faso) Yobe River Sokoto River Bani River Chari River Logone River Kainji Lake Digital Object Identifier Integrated Authority File
700721
de