B. DAKHLA OASIS, EGYPT C. SIWA OASIS, EGYPT D. GHARDAIA OASIS, ALGERIA E. GUERRARA OASIS, ALGERIA F. KUFRA OASIS, LYBIA G. SAN PEDRO DE ATACAMA, CHILE H. EN GEDI OASIS, ISRAEL I. TURPAN OASIS, CHINA J. YZAD OASIS, IRAN K. TAYMA OASIS, SAUDI ARABIA
A. INTRODUCTION
Oasis is a Greek word and means “inhabited place”.
An oasis is an area covered with vegetation in the desert. Because of different water sources oases can be classified into the following groups: - Groundwater oasis: The water is brought to the surface with a pump or a well - River water oasis: A river supplies the oasis with water from rain-laden areas. - Spring water oasis: A spring water oasis is located at places where groundwater table reaches the earth’s surface. It is the most common type of oasis. - Oasis with an artesian well: The groundwater rises to the surface because of overpressure. Oases were once very important for the caravan trade and agriculture but they lost their importance in times of modern transportation techniques. One of the most important products was once the date. But some of the North African oases had a structural change and could intensify their agriculture because of the use of deeper laying water resources. One of the biggest problems of oases is still the salinisation. It occurs whenever water evaporates because the soluble salts remain in the soil. The salinisation in some oases is extended so far that agriculture is not possible anymore.
A. DAKHLA OASIS, EGYPT
Dakhla is one of the five western oases in the Libyan Desert in Egypt. The 14 villages are situated in a swale surrounded by rocks and are home to 70.000 people. The oasis has 30.000 ha cultivable land where basically date palms, citrus fruits and mulberrys are grown
Siwa is also one of the five western oases in the Libyan Desert in Egypt. This oasis is 80km long, 2- 20km wide and located 18m under the sea level. In several villages live about 23.000 people. Most of them are farmers that cultivate date palms and olive trees.
Ghardaia (Algeria) is located in a valley called M`zab in the nothern part of the Sahara. The wadi Mzab supplies all oases in the valley with water after heavy rainfalls. In several smaller towns and villages live 82.500 peolple. Most of them are farmers and cultivate date palms. Ghardaia has its own airport and exports not only dats but also petroleum and natural gas.
The Kufra Oasis is located in the south east of Libya. In the 1970ies several big irrigation projects made intensive agriculrure possible. For the last 30 years the oasis was irrigated with fossile ground water. Today the ground water level is about 60m lowered. There are no data about how long the Kufra will be supplied with water. But scientist expect that this Oasis will dry out in only a few years.
San Pedro de Atacama is a town in the Atacama desert in Chile. It lies 2.443m high and has about 4900 mostly indigenous inhabitants. Because of its hight the temperature can drop below zero degrees at night. The river Rio San Pedro supplies the town with water and drains away after it passed the town.
San Pedro de Atacama, co-ordinates: 68°12'6.71"W, 22°55'5.98"S
G. EN GEDI OASIS, ISRAEL
En Gedi is an Oasis in the northern part of the desert Negev closed zo the Dead Sea in Israel. The oasis is administrated by a Kibbuz today that cultivate dates but finance itself manly with tourism and mineral water production. Because the sea level loweres En Gedi is endangered by huge collapses of vugs.
En Gedi Oasis, Israel, co-ordinates: 35°23'30.99"E, 31°27'29.24"N
H. TURPAN OASIS, CHINA
The Oasis Turpan lies on the Silk Road in west China. It is located in the Turfan Depression which is up to 154,5m under the sea level. The osis is home to more than 250.000 people. Canals supply Turpan with melt water from the Tienschan Mountans. Agricultural products are grapes and melons.
The Yzad Osis in Trand is one of the biggest Oases in the world with more that 500.000 inhabitants. Yzad is a cultivated osais since 3000 B.C. It is located 1203m above sea level and has therefore cold winters. The whole region is known for its textile products like silk and other industries.
The Tayma Osis in Saudi Arabia is one of the biggest and oldest oases in the world. It is located 830m above the sea level in a depression where the ground water is closed to the earth`s surface. Artificial irrigation made a the cultivation of 80.000 date palms possible
Tayma Oasis, Saudi Arabia, co-ordinates: 38°33'36.82"E, 27°37'37.95"N
Geographical Information Systems (GIS) and remote sensing. Mapping using a Blobal Positioning System (GPS). Geostatistics and Spatial Interpolations of modeling point data. Internet Mapping and atlas projects using public participation. This module counts 10 credits.
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