塔里木河下游生态保护目标和措施

Ecological Protection Objects and Restoration Measures in the Lower Reaches of Tarim River

针对2000—2009年塔里木河下游10次生态输水后生态环境的变化情况,提出新的生态保护目标:在距河500m以内以胡杨(Populus euphratica)为主的重点保护带,地下水埋深保持在≤4m,植被总盖度达到0.4～0.5;500～1 000m为基本保护带,以柽柳(Tamarixspp.)为主,地下水埋深为4～6m,植被总覆盖度达到0.3以上;>1 000m为一般保护带,随着输水累积量增加,地下水埋深达到6～8m,使现有植被不再退化;沿河两岸1 000m的植被保护恢复总面积应达到1 028km2;用水均衡法和潜水蒸散法重新估算的大西海子的下泄水量为2.3×108m3,比原规划减少了1.2×108 m3,其中2.0×108 m3为维护生态所用,另外还有0.15×108～0.3×108 m3为向台特玛湖输水的水量;应保持输水连续性,大西海子以下年泄水量不小于0.36×108 m3;为了保证向下游输水,必须加强水资源调控,通过整治源流,使到达干流的水量为44.2×108 m3,干流严禁开荒,加强对防护堤修建后生态环境变化的监测,下游采用漫溢漂种增加植被面积。

Aim at the environmental changes in the Lower Reaches of Tarim River after ten times of ecological water conveyance during 2000-2009,in this paper we put forward the new target of ecological protection.The major protection zone,dominated by Populus euphratica,is within the range of 500 m away from the river channel.The groundwater depth is maintained to be less than 4.0 m,and the total vegetation cover degree reaches to 0.4-0.5.The range of 500-1 000 m away from the river channel belongs to the basic protection zone where mainly grows Tamarix spp..The local groundwater depth is 4-6 m,and the total vegetation cover degree is over 0.3.The general protection zone is in the range of more than 1 000 m away from the river channel.With the increase of ecological water volume,the local groundwater depth reaches to 6-8 m.Thus the existed vegetation will not degenerate any more.The total area of vegetation protection and restoration within the range of 1 000 m along the two sides of the river channel should be 1 028 km2.The results calculated by water balance method and phreatic evaporation method indicate that the released water volume from Daxihaizi Reservoir is 2.3×108 m3,which is less than the planned released water volume of 1.2×108 m3.The water volume of 2.0×108 m3 is utilized for ecological conservation,and 0.15×108-0.2×108 m3 of them are flowing into Taitema Lake.The water conveyance should be maintained to be continuous,and the minimum annual released water volume to the Daxihaizi Reservoir is not less than 0.36×108 m3.For guaranteeing the water conveyance into the lower reaches,the relevant departments should enhance water resource regulation in the headstreams to make the water volume into the mainstreams reaching 44.2×108 m3.Reclaiming should be forbidden and environmental monitoring for embankment should be enhanced in the mainstreams.The method of flooding seeding is utilized in the lower reaches for increasing the vegetation area.