塔里木河流域下游绿洲演变对生态输水的响应

Response of oasis evolution to ecological water transport in the downstream of Tarim River Basin

参考前人对绿洲的定义和分类方法,对塔里木河下游人工绿洲、天然绿洲进行提取,分析生态输水前后人工绿洲和天然绿洲的面积变化特征、转化过程、重心迁移情况以及扩张与退缩的空间变化。结果表明:1990-2015年,塔里木河下游绿洲总面积先下降、后上升,人工绿洲不断扩张,10a平均增长量为46.78km^2,天然绿洲面积不断缩减,在2000年后有所上升。生态输水前(1990-2000年),塔里木河下游来水量减少,导致大面积草地退化,天然绿洲面积减少;生态输水后(2000-2015年),部分未利用土地得到了利用,变成河渠、水库、湖泊、灌木林和高覆盖度草地,塔里木河下游生态有所恢复。下游绿洲重心先往西北,再往南方,最后又往东南方向迁移。绿洲主要向西北和东南方向扩张,1990-2000年的扩张区域主要集中于英苏上游区域;2000-2010年期间,台特玛湖地区绿洲面积增加明显;绿洲缩减区域分布广而零星。

Referring to the definition and classification method of oasis proposed by previous researchers, the artificial and natural oases were extracted in the downstream of the Tarim River. After that, this paper analyzed the area change characteristics, transformation process, gravity center migration, and spatial variation of oasisization and desertification during the period of 1990-2015. The results show that, from 1990 to 2015, the total area of oasis in the downstream of Tarim River Basin decreased firstly and then increased. The area of artificial oasis continued to expand with a 10-year average growth rate of 46.78 km^2. The area of natural oasis continued to shrink, but increased after 2000. It is because that the amount of river discharge decreased, resulting in the degradation of grassland and the reduction of natural oasis before the ecological water transport(1990-2000). After the ecological water transport(2000-2015), some unused land was utilized again. The center of the oasis traveled to the northwest, then to the south, and finally to the southeast. In addition, the oasis mainly expanded to the northwest and southeast, while the oasis reduction area was sporadic.