塔里木河中游滞洪区的形成及其对生态环境的影响

塔里木河位于我国新疆内陆干旱区,是我国最大的内陆河,全长1321km.近40a来,在阿克苏河、叶尔羌河、和田河、开都河 孔雀河四条源流出山口天然来水量未减少,且在20世纪90年代增加7%的情况下,由于源流区人类活动的影响和粗放型农业,补给塔里木河水量以年平均2500×10⁴m³的速率减少,加之中游区新生滞洪区耗水严重,进入下游的水量锐减.20世纪70年代以来又被大西海子水库几乎全部拦蓄,导致最下游320km河道断流近30a,地下水位下降,植被衰退,沙漠化进程加快,"绿色走廊"危在旦夕,生态环境恶化,已影响到流域人类的生存安全.

Flood Detention Region in the Middle Reaches of Tarim River Mainstream and Its Impact on Ecological Environments

The Tarim River Basin is located in the southern half of Xinjiang Uygur Autonomous Region, PRC. From the confluence of its three main contributing tributaries, the Tarim River mainstream extends 1321 km to Taitema Lake. The mainstream can be classed into the upstream with 495 km from Xiaojiake to Yinbazar, the middlestream with 398 km from Yinbazar to Kara and the lowerstream with 428 km from Kara to Taitema Lake. A number of rivers fed by snowmelt and glacier melt begin in the mountains and drain into the basin with average annual virgin flow of about 35 billion m³. A number of other subbasins exist within the Tarim Basin that does not contribute flows to the Tarim River because all of their flows either naturally evaporate in the desert or are used in irrigated agriculture areas. Peak flow months in the rivers are July, August and September. Lowest flow occurs in the period from January through April. Total streamflow of the four headstreams of the Tarim River in 2001 is 266.5×10⁸m³, more 40.70×10⁸m³ than annual mean streamflow, increasing 18% to annual mean value. Annual mean streamflow at Aler Gauging Station where the Tarim River mainstream begins was 46.00×10⁸m³. The interzone consumed water of the Tarim River mainstream are estimated to be 15.33×10⁸m³ for the upper course, account for 33.3% of Aler annual mean streamflow; 23.99×10⁸m³ for the middle course, 52.2% of Aler ones and 6.680×10⁸m³ for the downstream course,14.5% of Aler ones. The consumed water of both upstream and middlestream courses sum up 39.32×10⁸m³, account for 85.5% of annual mean streamflow at Aler Gauging Station. Historical annual flows average over 40×10⁸m³, but for the past two decades there has essentially been no flow below Daxihaizi Reservoir, 300 km upstream of Taitema Lake. In 2001, an emergency water diversion project was carried out in the "green corridor", transfer water from Bosten Lake to the Taitema Lake, and fed the "green corridor", ended the 30-years no flow history of 300 km upstream of the Taitema Lake, and ecological environment started to be restoring.