Sahel zone

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The location of the Sahel in Africa is marked in blue.

The Sahel zone (the Sahel ) in Africa is the elongated, semi-arid transition zone between the Sahara desert in the north and the humid savannah in the south. With the exception of a small part in East Africa, the Sahel lies in the greater Sudan landscape , which also includes the wet savannah.

In the Sahel there are severe droughts that lead to famine , usually only a few years apart . In 2007, on the other hand, floods occurred in large parts of the Sahel zone, leaving millions of people homeless.

The richest country in the Sahel is Sudan with a nominal per capita income of $ 1,428 (2017), the two poorest are Burkina Faso ($ 664, 2017) and Niger ($ 440, 2017).

Name interpretation

According to Henry N. Le Houérou, 1989, Auguste Chevalier was the first to use the term “Sahel” in 1900 for the area around Timbuktu in Mali . Two possible origins of the word from Arabic are suspected: one is calledساحل / Sāḥil  shore or coast - to the traveler coming from the sand sea, the vegetation of the Sahel appears as a saving shore. On the other hand meansسهل / S'hel   flat, flat land.


Position and extent

Isolines of the annual precipitation in the Sahel zone and national borders. Colored 100 to 600 mm / year, without coloring 50 and 700 mm / year.

Large parts of the Sahel ( Senegal , Mauritania , Mali , Burkina Faso and Niger ) used to belong to French West Africa and to French Equatorial Africa ( Chad ). Some authors, especially, but not only in a political context, only localize the Sahel in these states. Gambia , a former British enclave in Senegal, is located on the southern edge of the Sahel and is sometimes included in the Sahel states. Other authors grasp the Sahel further on a meteorological and vegetation-geographical basis, in the west sometimes including the Cape Verde Islands , in the east beyond Lake Chad and often as far as the Nile , i.e. including the Darfur and Kurdufan regions in Sudan , sometimes as far as the Red Sea in the north Eritrea , rarely as far as Somalia . Without the last-mentioned section, due to the broader seasonal distribution of precipitation in that coastal plain, the Sahel zone extends over a length of 5900 km.

The width of the Sahel zone is roughly 600 km. The limits are often given with reference to the mean annual precipitation, 100 ± 50 mm / a for the northern, 600 ± 100 mm / a for the southern limit, whereby the dispersion of the information is not entirely arbitrary by the authors, but partly due to the influence of the soil is based on the distribution area of ​​defining plant species.


In the Sahel , the precipitation brought in by the southwest monsoon is concentrated in a few, heavy downpours, with the maximum of the rainy season in August. In the north of the Sahel the scant rain falls, if at all, mostly in July / August, further south the rainy season lasts from June to September. In the long dry seasons that are completely free of precipitation, the Harmattan , a NE trade wind, blows from the Sahara , carrying evaporating water back to the humid south. The fact that the mean climatic temperature is never below 20 ° C in any month contributes to evaporation.

Sahel precipitation index from 1901 onwards. The index shows the precipitation during the rainy season in a certain measurement area, minus a mean value. The decline between the 1950s and 1980s is striking, followed by a slow increase.

The mean values ​​of the precipitation are not of great importance for the farmers, as the variability is high, both averaged over the region from year to year and over the year from place to place. Sometimes a large part of the annual precipitation falls in a single heavy rain. The predominantly hard and dry soil in the Sahel can then only absorb small amounts of water. This problem is exacerbated by climate change: predictions from climate models that the Sahara will warm more than tropical Africa and that heavy rain events will become more intense due to the steeper gradient have been confirmed by satellite data.

Even averaged over several years, the precipitation fluctuates more strongly than would be expected with uncorrelated annual values. So they sank in the 1970s and early 1980s, so that the Sahara continued to expand towards the Sahel (see desertification ). This trend reversed in the mid-80s, and rainfall has increased since then. Compared to 1980, the Sahel is much greener today. Notwithstanding this, the AU has started building a “ Green Wall ”. On the other hand, it can be observed that many species of the Sahel zone can be found further south in the Sudan zone .



The farmers in the Sahel mainly cultivate millet. But manioc , yams and potatoes are also grown for subsistence farming (self-sufficiency). Over the years, due to the enormous increase in population, they increasingly relocated their arable land to the north, exceeding the agronomic dry line and irrigation of the fields is now necessary. The Zaï is a common system for restoring degraded arid areas and increasing soil fertility . In various villages, attempts are being made, often with the help of development aid organizations, to counter the widespread malnutrition caused by horticulture in irrigation technology, but setbacks occur again and again due to the lack of water. Only very sophisticated systems of crop production that minimize water requirements are sustainable.


The second important aspect of agriculture in the Sahel is livestock. In the course of the enormous population growth, people are increasing their herds of cattle and goats. In addition, quantity is more important to them than quality. This means that the many animals eat the plants and their roots and the already hard, dry soil is trodden and compacted by the animals. This increases the desertification of the soil. In addition, due to periods of high rainfall, well construction and development aid, the farmers stopped grazing, i. This means that one no longer wandered with the precipitation. All of these factors ultimately lead to excessive overgrazing , which means that plants can no longer regenerate because they are constantly being eaten away, the soil is acidified by the urine and faeces of the animals and more and more trees are dying because the goats nibble on their bark.

growth of population

On top of all this, there is population growth due to fewer deaths and the desire for many children, who are necessary for old-age provision. It also gives the family greater recognition. The population is increasing by more than 3% annually. The consequences are that the population is growing faster than the arable land; the cultivation style is changed at the expense of the fields; The need for millet is increasing, which in turn leads to an expansion and even greater use of the fields and the water reserves are more stressed. Therefore the soil quality deteriorates and there are more frequent crop failures. In addition, the younger residents in particular move to cities in the hope of being able to lead a better life there. As a result, fewer and fewer and primarily older people are left behind in the countryside.



Biggest rivers

More rivers


See also

Web links


  • Marcel Kritissou and Pauline E. Ginsberg: The Sahel - Focus of Hope, Focus of Fear. Adonis & Abbey, London 2014, ISBN 978-1-912234-64-6 .

Individual evidence

  1., September 15, 2007: Flood threatens millions of Africans ( Memento of October 13, 2007 in the Internet Archive )
  2. ^ A b c d Henry Noël Le Houérou: The Grazing Land Ecosystems of the African Sahel. Springer, 1989, ISBN 978-3-642-74459-4 .
  3. UNEP / FAO: Final Report: UNEP / FAO World and Africa GIS Data Base. December 1984.
  4. ^ A b Theodore Cohn: The Sahelian Drought: Problems of Land Use. Canada's Journal of Global Policy Analysis, 1975, doi: 10.1177 / 002070207503000304 .
  5. United States Agency for International Development : Proposal for a Long-Term Comprehensive Development Program for the Sahel, Part II, Technical background papers. Report to the United States Congress, 1960, limited preview in Google Book search.
  6. Jeremy Swift: Sahelian Pastoralists: Underdevelopment, Desertification, and Famine. Annual Review of Anthropology 6, 1977, doi: 10.1146 / .
  7. Observatoire | Niger Basin and Inner Niger Delta: General pattern of rainfall. 2017.
  8. Joint Institute for the Study of the Atmosphere and Ocean (JISAO, a NOAA - Cooperation ): Sahel Precipitation Index (20-10N, 20W-10E), 1901 - 2017. doi: 10.6069 / H5MW2F2Q .
  9. MJMortimore and WMAdams: Working the Sahel - Environment and society in northern Nigeria. Routledge, 1999, ISBN 978-0-415-14096-6 ( Google Preview ).
  10. floor in the Sahel,
  11. C. Taylor et al .: Frequency of extreme Sahelian storms tripled since 1982 in satellite observations. Nature 544, 2017, doi: 10.1038 / nature22069 .
  12. Mike Hulme: Climatic perspectives on Sahelian desiccation: 1973-1998. Global Environmental Change 11, 2001, doi: 10.1016 / S0959-3780 (00) 00042-X ( preprint ).
  13. L. Olsson, L. Eklundh, J. Ardö: A recent greening of the Sahel — trends, patterns and potential causes. In: Journal of Arid Environments. Vol. 63 (3), 2005, pp. 556-566. doi: 10.1016 / j.jaridenv.2005.03.008
  14. ^ R. Wittig, K. König, M. Schmidt, J. Szarzynski: A Study of Climate Change and Anthropogenic Impacts in West Africa. In: Environmental Science and Pollution Research. 14, 2007, pp. 182-189. PDF file
  15. Hans-Heinrich Bass, Klaus von Freyhold, Cordula Weisskoeppel: Harvesting water, protecting trees: Food security in the Sahel. Bremen 2013, accessed on January 1, 2013 (PDF; 2.9 MB)
  16. The unlimited population growth ,