黑河调水对下游东、西居延海生态环境的影响

针对黑河流域生态系统日益严峻恶化的局面,2000年开始对黑河下游进行了调水。东、西居延海是黑河尾闾,调水以前均干涸多年。通过实地调查、遥感等手段,分析了干涸多年的黑河尾闾东、西居延海调水后水资源、植被及生态环境的恢复情况。结果表明,(1)黑河流域水量统一调度以来,东居延海分别于2002~2006年连续5年10次进水,总计入湖水量达到1.797 7亿m3,最大水面面积达35.7 km2;西居延海也在2003年进水,入湖水量达到0.272 3亿m3,东、西居延海总计入湖水量达到2.07亿m3。(2)调水前东居延海及四周植被覆盖度低,植物种类少,普遍生长不良,调水期末湖内及四周植被覆盖度明显增大,植物种类增加,生长较好,植被呈现向良性演替方向发展的趋势。(3)遥感调查表明,黑河下游东、西居延海调水后草地面积增加了15.35 km2,高覆盖度灌木林面积增加了5.9 km2,而中、低覆盖度灌木林面积减少了8.59 km2,戈壁滩、沙化面积减少了19.98 km2,生态环境也有了极大改善。以上结果表明,调水5年多来东、西居延海生态环境正向良好的方向转变。

Effect of transferring water on ecological environment in east and west Juyanhai lake at the lower reaches of Heihe River

Aiming at the more and more serious situation of the ecological system of the Heihe watershed,the water resource was transferred to the lower reaches of Heihe River from 2000.The east Juyanhai lake and west Juyanhai lake are the terminal lake of Heihe river,which have been dry for many years before transferring water.Through the measures of investigation and remote sensing,the recovery of water resource,vegetation and ecological environment in east Juyanhai lake and west Juyanhai lake were analyzed.The results indicate:(1) Since water is allocated in Hei river watershed,water have be dispatched into Dongjuyanhai lake from 2002 to 2006 for ten times,and the total quantity is 179.77 million cubic meter,and the maximal surface is 35.7 square kilometer.Water have also be dispatched into Xijuyanhai lake in 2004,and the total quantity is 27.23 million cubic meter.(2) Vegetation coating degree and biology diversity increase since water is dispatched into east Juyanhai lake.(3) Through remote sensing investigation,the area of meadow increases by 15.35 square kilometer,and the area of high overlay degree shrubbery increases by 5.9 square kilometer,and middle-low overlay degree shrubbery lessens by 8.59 square kilometer,and the area of Gobi-Dene lessens by 19.98 square kilometer.The above findings show that the ecological environment of east and west Juyanhai lake is changing better and better during 5 years after transferring water.