运用统计方法分析塔里木河下游英苏、喀尔达依、阿拉干三断面输水前后归一化植被指数(NDVI)的差异大小并推测河畔植被对输水的响应程度。结果表明:随着输水进行,研究区NDVI与地下水埋深逐渐呈负相关趋势,NDVI增幅随地下水埋深减小逐渐增大;输水前后相同断面NDVI差异极显著,根据输水前后NDVI差值大小确定植被恢复速度为:英苏>喀尔达依>阿拉干;各断面NDVI在输水前没有差异,输水后断面间NDVI差异显著,根据差异大小确定恢复程度顺序为英苏>喀尔达依>阿拉干;以大西海子水库周边NDVI为参照,确定经7年8次生态输水英苏、喀尔达依、阿拉干三断面植被恢复度分别为20.2%、18.4%和8.4%。以上研究表明,研究区植被恢复仍然有限,坚持持续输水很有必要。
Using statistical methods, this paper analyzed the NDVI differences before and after water transfer to Yinsu section, Kaerdayi section and Alagan section at Daxihaizi reservoir in the lower reaches of Tarim River as well as speculated the level of response of riparian vegetation at these sections to water transfer. The results showed that with the practice of water transfer, the study area’s NDVI and the groundwater level gradually presented negatively correlating trends, with the increase in groundwater level, the range of NDVI increase gradually increased; before and after water transfer NDVI difference varied significantly on the same sections, according to the degree of NDVI difference before and after water transfer the order of vegetation restoration speed is Yinsu> Kaerdayi> Alagan; no difference of NDVI among sections was observed before water transfer after at NDVI differs significantly among sections, according to the degree of vegetation restoration, the order is Yinsu> Kaerdayi> Alagan; taking NDVI of the neighboring Daxihaizi Reservoir as a reference, vegetation restoration rate of the three sections respectively is 20.2%,18.4% and 8.4%. The above study shows that, after seven years the ecological restoration of vegetation is still limited by water supply, hence, continuous water transfer is quite necessary.
[1] 闫正龙,汤国安.塔里木河下游生态应急输水植被恢复的遥感监测[J].水土保持通报,2004,25(3):58~60.
[2] 孙涛,李纪人,杜龙江.塔里木河下游应急输水前后生态变化遥感监测分析[J].中国水利水电科学研究院学报,2004,2(3):179~188.
[3] 李霞,侯平,董新光,等.应急输水对植被响应效应研究.塔里木河下游应急输水与生态改善监测评估研究.110~112.
[4] 宋郁东,樊自立,雷志栋,等.中国塔里木河水资源与生态问题研究[M].乌鲁木齐:新疆人民出版社,2000.395~410.
[5] 丁建丽,等.基于NDVI的绿洲植被生态景观格局变化研究[J].地理学与国土研究,2002,18(1):23~26.
[6] 杨鹏年.塔里木河下游间歇输水条件下地下水恢复与植被响应研究.乌鲁木齐:新疆农业大学, 2005. 90~91.