|
Tuat or Touat (Berber language: ⵜⵓⵡⴰⵜ, ''Tuwat'') is a natural region of desert in central Algeria that contains a string of small oases. In the past, the oases were important for caravans crossing the Sahara desert. ==Geography== Tuat lies to the south of the Grand Erg Occidental, to the east of the Erg Chech and to the south east of the Tademaït Plateau. It contains a string of small oases strung out along the eastern edge of the Wadi Messaoud, a continuation of the Wadi Saoura. The oases extend over a distance of 160 km from the district of Bouda in the north to Reggane in the south. The largest town in the region is Adrar, 20 km south east of Bouda. Adrar was established by the French after their conquest in 1900 and had a population of 43,903 in 2002. Associated with each oasis are small walled villages called ''ksour'' (singular ''ksar'' or ''gsar''). There are also some forts (''kasbahs''), most of which have been abandoned. There is almost no rainfall in the region and the agriculture depends on groundwater from the Continental Intercalary (''Continental Intercalaire'' in French), an enormous aquifer that extends for over 600,000 km2, an area that includes parts of Algeria, Libya and Tunisia. The Continental Intercalary is a layer of porous sandstone deposited between the Moscovian and the Cenomanian periods. It forms the deeper of the two aquifers of the North Western Sahara Aquifer System (NWSAS). Tuat is situated at the south western boundary of the Continental Intercalary where the aquifer lies only 2–6 m below the surface. The oases contain 700,000-800,000 date palms (''Phoenix dactylifera'') in an area of 4,500 hectare. The palm groves are irrigated by a system of ''foggara''s. These are traditional gravity catchment systems which consist of a tunnel constructed with a gentle uphill gradient from the low ground near the wadi into the aquifer lying under the nearby higher ground. Vertical access holes every 10–20 m along the tunnel provide ventilation and facilitate the construction and maintenance. Many of the ''foggaras'' are over a kilometre in length. They typically provide flow rates of between 2 L/s and 3 L/s. In 1963 the region of Tuat contained 531 ''foggaras'' of which only 358 were functioning. The total combined flow rate was approximately 2000 L/s. Foggaras are expensive to construct and to maintain. As they collapse they are often not repaired. Instead, water is obtained using vertical wells and electric pumps allowing grain to be grown using a center pivot irrigation system. A single well can provide 30 L/s to 50 L/s of water. In addition to water, the rock beneath Tuat contains pockets of natural gas. Sonatrach, the Algeria state-owned oil company, is collaborating with foreign companies in joint ventures to exploit these gas reserves. Sonatrach and the China National Oil & Gas Exploration & Development Corporation (CNODC) have constructed a refinery near the village of Sbaa, 40 km north of Adrar. This began operating in 2006. Separate projects led by Gaz de France (GDF Suez) and Total are both scheduled to start supplying gas in 2013. A pipeline is being built to connect to Hassi R'Mel. To the north of Tuat is Gourara, a similar region also containing oases with date palms irrigated by ''foggaras''. The largest town, Timimoun, is 162 km north east of Adrar. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tuat」の詳細全文を読む スポンサード リンク
|