生态输水前后塔里木河下游绿洲特征分析

Characteristics of Oasis before and after the Ecology Water Transportation in Lower Reaches of the Tarim River

依据樊自立等人对人工绿洲、天然绿洲的定义及分类,对塔里木河下游人工绿洲、天然绿洲包含的要素进行提取,并根据前人对干旱区人工、天然绿洲适宜配比的研究,结合相应的遥感影像数据,对塔里木河下游1990—2000年、2000—2010年人工绿洲和天然绿洲的变化规律及其比例进行分析,探讨该区人工绿洲和天然绿洲的适宜配比。主要结果为:1990—2010年期间,塔里木河下游人工绿洲平均以19.09 km^2/a的速率增加,而天然绿洲平均以13.20 km^2/a的速率减少。输水前在生态系统的退化过程中,高覆盖草地面积减少了43.91%,湖泊面积100%消失,同时水库面积减少了45.28%;输水后,高覆盖草地面积减少量大有好转,10 a间只减少了6.79%,水库面积增加了392.44%。塔里木河下游流域在生态输水前,耕地增加了12.31%,生态输水后,耕地增加了30.37%。1990—2010年间,而绿洲总面积(人工+天然)不变,变化主要是发生在人工绿洲与天然绿洲之间的相互转化,天然绿洲逐渐被人工绿洲替代,平均每增加1份面积的人工绿洲就要失去1.1份天然绿洲。

According to the classification of artificial and natural oasis proposed by Fan Zili et al,the change law and proportion of artificial and natural oases in Lower Reaches of the Tarim River during 1990-2000 and 2000-2010 were studied on the basis of the previous studies and the remote sensing images data,and the appropriate proportion between artificial and natural oasis was discussed. The mainly results as follows：During 1990 to 2010,artificial oasis is expanded at a rate of 19.09 km^2/a,while natural oasis is shrank at a rate of 13.02 km^2/a. Before the ecology water transportation,the high-cover grassland area,lake area and reservoir area deduced by 43.91%,100% and 45.28%,and the cultivated land increased by 12.31%,respectively. After the ecology water transportation,high-coverer grassland area only decreased by 6.79%,the reservoir area increased by 392.44% and cultivated land increased by 30.37%. The total area of oases（the artificial＇s ＋ natural＇s） basically remain unchanged, and the changes mainly occurred in the reciprocal transformation between artificial and natural oases. The natural oasis was gradually replaced by artificial oases in recent 20 years,and 1 unit area of artificial oasis increased, 1.1 unit area of natural oasis decreased.