间歇性输水影响下的2001-2011 年塔里木河下游生态环境变化

采用2001-2011 年野外调查资料和卫星遥感影像数据,对生态输水影响下的塔里木河下游地下水、植被变化特征进行分析,并探讨了典型断面植被对地下水埋深变化的响应关系。结果表明:(1) 各断面地下水位变化过程与河道来水过程密切相关,近10 年来经历了显著抬升(2000-2005 年)—缓慢降低(2006-2009 年)—小幅抬升(2010 至今) 的过程,主要表现为随生态输水量的改变呈波动变化;地下水位抬升幅度与生态放水量的相关系数达0.78,与生态放水持续时间的相关系数为0.70。(2) 2001-2011 年塔河下游植被覆盖面积总体上呈增加趋势,其中灌木林地和草地变化显著,林地和耕地面积呈小幅度变化;植被覆盖度的变化主要表现为2001-2006 年显著提高和2006-2011 年小幅变化。(3) 植被覆盖度随地下水位的抬升呈现出增加的趋势;垂直河道的方向上,同时期植被覆盖度与地下水埋深空间分布特征一致,均以输水河道为轴向两侧植被覆盖度(地下水埋深) 逐渐降低(增大);平行河道的方向,植被覆盖度对地下水埋深的响应幅度随着离大西海子水库距离的增加而减小。

Eco-environmental change in the lower Tarim River under the influence of intermittent water transport

For the sake of improving the eco-environment, and preventing degradation of the vegetation, the water transport project in the lower Tarim River was carried out in April 2000. According to the water path, temporal and spatial distributions of water resources in this region were greatly changed in the past 10 years. As a result, the eco-environment condition has also changed obviously. In this paper, field surveys data and remote sensing data from 2001 to 2011 were used to analyze the variation of groundwater level and natural vegetation; and the vegetation response to the groundwater level variation in typical sections were also discussed. The results indicated that (1) the fluctuation of groundwater level in each section is closely related to the quantity and duration of the water transport, and shows a process from a significant rise to slow reduction, and to a slight rise during the 10 years; the correlation coefficient of groundwater depth variation and water transfer quantity is approximately 0.78, and the correlation coefficient of groundwater depth variation and water transport duration is 0.7. (2) The area of vegetation cover in this region showed an increasing trend from 2001 to 2011, and the biggest area change in natural vegetation occurred in shrub land; the fraction of vegetation coverage were increased obviously during 2001-2006, and changed slightly from 2006 to 2011. (3) The fraction of vegetation coverage was found to increase along with the rise of groundwater level. In vertical direction of the river, ground water level and vegetation coverage showed a similar spatial distribution: the more distance away from river the lower groundwater level is, the lower fraction vegetation coverage. In parallel direction of the river, the response intensity of the fraction of vegetation coverage to groundwater level showed a decreasing trend along the distance from Daxihaizi reservoir.