为了补给塔里木河下游断流的河道和挽救濒死的荒漠群落,自2001年塔里木河实施了生态输水工程,流域生态环境得到初步改善,实现了流域经济社会发展与生态环境保护的双赢。在生态输水20 a之际,为了评估输水的生态效应,基于多源遥感数据MOD13Q1和MCD12Q1数据,通过数学统计方法调查了塔里木河下游归一化植被指数（NDVI）和植被覆盖度的时空变化。结果表明：经过近20 a的生态输水,塔里木河下游的NDVI从2000年的0.14增大到2020年的0.21,增幅达33.3%,植被面积从2000年492 km²扩大到2020年的1423 km²;其中,低、中、高植被覆盖度的面积相较于2000年分别增多了277 km²,537 km²和132 km²,增幅分别达到20.8%,448.0%和190.0%,中段的植被面积和植被覆盖度的增幅均高于上、下段区域的增幅。NDVI和植被覆盖度均表现为距离河道2 km范围内的值较大,且增幅也较大,2 km以外NDVI和植被覆盖度逐渐变小,且增幅也较小。空间上来看,约有57.1%的区域NDVI和植被覆盖度呈现显著增加趋势,显著减小的区域都不超过2.0%。Hurst指数表明超过75.0%以上的区域这种变绿的趋势会在未来继续保持,仅有6.1%的区域生态会继续恶化。综合评估塔里木河输水工程的生态效应,对于干旱区荒漠的保育恢复治理、生态水资源管理等方面具有重要的科学意义。

An ecological water conveyance project has been implemented since 2001 in the lower Tarim River, Xinjiang, China to replenish its broken river channel and save dying desert communities. The ecological environment of the basin of the river was initially improved, achieving a win-win situation considering both economic and social development and ecological environmental protection of the basin. In this paper, the spatiotemporal changes in the normalized difference vegetation index (NDVI) and vegetation cover in the lower Tarim River were investigated using mathematical statistical methods based on multisource remote sensing data (MOD13Q1 and MCD12Q1) to evaluate the ecological effects of water conveyance in the last 20 years. The results show that the NDVI of the lower reaches of Tarim River increased by 33.3% (from 0.14 in 2000 to 0.21 in 2020) and that the vegetation area increased by 188.0% (from 492 m² in 2000 to 1423 m² in 2020). Compared with those in 2000, areas with low, medium, and high vegetation coverage increased by 277 m², 537 m², and 132 m², respectively (increase rates of 20.8%, 448.0%, and 190.0%, respectively). The increases in the vegetation area and vegetation cover in the midstream section were higher than those in the upper and lower reaches. The NDVI and vegetation cover both showed large increases within 2 km from the river banks, which gradually became smaller beyond 2 km. Spatially, about 57.1% of the areas showed a significant increasing trend in NDVI and vegetation cover, and no more than 2.0% of the areas showed a significant decrease. The Hurst index indicates that more than 75.0% of the areas with this greening trend will continue in the future and that only 6.1% of the areas will continue to ecologically deteriorate. A comprehensive assessment of the ecological effects of Tarim River water conveyance project is of great scientific significance for the conservation and restoration management of arid zone deserts and ecological water resource management.