Sahel
enUKSa·hel
S0021250 (sə-hāl′, -hēl′)Sa•hel
(səˈheɪl, -ˈhil)n.
| 单词 | sahel |
| 释义 | SahelenUKSa·helS0021250 (sə-hāl′, -hēl′)Sa•hel(səˈheɪl, -ˈhil)n. SahelenUKSahel(sähĕl`), name applied to the semiarid region of Africa between the SaharaSahara[Arab.,=desert], world's largest desert, c.3,500,000 sq mi (9,065,000 sq km), N Africa; the western part of a great arid zone that continues into SW Asia. Extending more than 3,000 mi (4,830 km), from the Atlantic Ocean to the Red Sea, the Sahara is bounded on the N by ..... Click the link for more information. to the north and the savannassavanna or savannah , tropical or subtropical grassland lying on the margin of the trade wind belts. The climate of a savanna is characterized by a rainy period during the summer when the area is covered by grasses, and by a dry winter when the grasses wither. ..... Click the link for more information. to the south, extending from Senegal and Mauritania on the west, through Mali, N Burkina Faso, Niger, N Nigeria, and Chad, to Sudan and Eritrea on the east. It has more rainfall (8–16 in./20–40 cm) and better grazing lands than the Sahara, but it is periodically afflicted by droughts that reduce its normally meager water supply and shatter its grazing and agricultural economy. A particularly prolonged and devastating drought from 1967 to 1974 contributed to the starvation of of hundreds of thousands of people, and forced the mass migration southward of many others. Sahelthe narrow (320–480 km) band of semideserts and desert savannas in Africa that are transitional between the deserts of the Sahara and the characteristic topography of the Sudan. The Sahel stretches for more than 4 million sq km from Mauritania and Senegal in the west through Mali, Upper Volta, and Niger to Chad and the borders of the Sudan. The area of the Sahel varies from year to year, depending on the amount of annual precipitation (100–350 mm) in the north to 300–600 mm in the south). Rain falls in the summer for a period ranging from two or three weeks to three months, but 80 or 90 percent of the moisture evaporates. The Sahel is periodically subject to disastrous droughts, when virtually the entire area becomes uninhabitable desert; this was the case in 1941 and 1942 and from 1972 to 1975. The northern Sahel has mostly sparse semidesert vegetation, such as turf grasses, shrubs, and low-growing trees, especially acacias. This region is inhabited by nomadic herders who raise cattle, sheep, and goats. In the southern Sahel, sparse thorn forests, groves of palms (doom and palmyra), and baobabs predominate. Nomads and communities of settled land cultivators live in the area, and millet and peanuts are grown. sahel[sə′hel] |
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