以河湖为主体的塔里木河下游地表水体的面积受到输水工程的影响,在区域水循环、调节水平衡中扮演着重要角色。基于近20 a塔里木河下游Landsat 5、Landsat 7和Landsat 8影像资料和生态输水数据,综合采用Google Earth Engine（GEE）计算平台和多元统计分析方法,对地表水体面积变化及其对生态输水的响应进行了系统分析。结果表明：（1） 2000—2019年,塔里木河下游区域的地表水体、季节性水体和永久性水体的面积均呈现波动上升趋势,速率分别为15.54 km²·a^-1、7.12 km²·a^-1和8.41 km²·a^-1;塔里木河下游上段（大西海子水库—英苏,不包括大西海子水库）、中段（英苏—阿拉干）和下段（阿拉干—台特玛湖）区域的季节性水体和永久水体面积也均呈现波动增加趋势,其中下段区域的增加速率最大,其值分别为5.23 km²·a^-1和8.24 km²·a^-1。（2） 生态输水引起的地表水体面积增加主要表现在台特玛湖湖区,2019年台特玛湖湖区的地表永久水体和季节性水体面积分别约为267.27 km²和188.00 km²,总体水面积约为455.27 km²,相比2000年（约38.19 km²）增加了417.08 km²（约10.92倍）。（3） 近20 a来,研究区域地表水体面积,尤其是永久水体面积变化与塔里木河下游生态输水量密切相关;2007—2009年输水量下泄水量较少,直接导致研究区域在2009年地表水体和季节性水体的面积均减少到最低点。研究结果有助于全面理解塔里木河下游生态输水对地表水体变化的影响,为区域水生态保护提供科学依据。

Water is a key restricting factor of socioeconomic development and eco-environmental protection in the arid inland river basins of northwest China. Because of ecological problems caused by climate change and the overexploitation of water resources in the Tarim River Basin (e.g., river breakup, drying-up of lakes, and degradation of vegetation cover), a national ecological water conveyance project has been officially implemented in the lower reaches of Tarim River since 2000. So far, the region’s ecological environment has improved steadily, and studies have evaluated the impacts (e.g., changes in groundwater level and vegetation cover) of the ecological water conveyance project. However, there are relatively few systematic studies on the changes in the area of surface water in the lower reaches of Tarim River in the past 20 years. On the basis of the Landsat 5, 7, and 8 images and the annual water conveyance quantity, this paper used the Google Earth Engine, the surface water extraction method, and the multiple statistic methods (e.g., the Mann-Kendall trend test and the Pearson correlation coefficient) to quantitatively analyze the spatiotemporal changes of the surface water and evaluated the impacts of the ecological water conveyance project on the surface water area. The main results are as follows. Firstly, from 2000 to 2019, a fluctuating upward trend was detected in the overall surface water area, seasonal water area, and permanent water area, with increase rates at 15.54 km²·a^-1, 7.12 km²·a^-1, and 8.41 km²·a^-1, respectively. A fluctuating upward trend has also been detected for all three subregions: the upstream region from Daxihaizi Reservoir to Yingsu station, the upstream region from Yingsu station to Alagan station, and the downstream region from Alagan station to Lake Taitema. Of these, the downstream region had the largest increase rate for both the seasonal water and permanent water areas, with values at 5.23 km²·a^-1 and 8.24 km²·a^-1, respectively. In addition, the increase in surface water area in Lake Taitema was the main factor for the expansion of surface water area in the lower reaches of Tarim River. In 2019, the permanent surface water area, the seasonal water area, and the total surface water area of Lake Taitema were about 267.27 km², 188.00 km², and 455.27 km², respectively; the total surface water area of Lake Taitema in 2019 was evaluated to have been increased by 417.08 km² (about 10.92 times) over that in 2000 (about 38.19 km²). Finally, in the past 20 years, there is a strong positive correlation between the surface water area (especially the permanent water area) and the water quantity of the ecological water conveyance project. The water quantity of the ecological water conveyance project was extremely low during 2007—2009, which directly caused the lowest values of the total surface water area and the seasonal surface water area. Results obtained from this study can contribute to the comprehensive understanding of the impact of ecological water conveyance in the lower reaches of Tarim River and provide a scientific basis for developing regional water ecological protection.