The inland lakes in arid regions, especially the terminal lakes, are highly sensitive to the influence of human activities and climate change. In order to analyze the evolution of the area of water in Ulungur Lake (Buluntuohai Lake, Jili Lake) and the main causes of those changes, 3S technology, satellite data preprocessing, water extraction and database construction methods are combined with consideration of climatic changes and human activity in this study. The data in this study include 11 phases of remote sensing image data, field mapping data and relevant attribute data of the study area from 1977 to 2017. The results demonstrated the following. (1) Over the past 40 years, the change in Ulungur Lake's area was characterized by natural expansion, fluctuation stability, and recovery increase. Significant changes were mainly concentrated in the waters of Zhonghaizi, Xiaohaizi, Camel's Neck, and the waters near Akekule. (2) The period from 1977 to 1995 was the expansion period of the lake water area, and human activities were the main driving factors. The period from 2000–2017 was a smaller period of expansion of the lake water area, with warmer and more humid climate trends combined with human activities driving the change. (3) The water area that was extracted based on the MNDWI water index method can increase the contrast between bodies of water and buildings, which can aid in interpreting and extracting water element information from flat terrain and single types of surface features. This can provide an effective technical means for quantitative and dynamic analysis of the temporal and spatial changes in lake water area.

Ecological sluices were constructed along the Tarim River to supplement the ecosystem’s water supply. However, the impact of water regulation by these sluices on the surface water area (SWA) and its relationship with the vegetation response remain unclear. To increase the efficiency of ecological water use, it is crucial to study the response of SWA to water control by the ecological gates and its relationship with vegetation restoration. We utilized the Google Earth Engine (GEE) cloud platform, which integrates Landsat-5/7/8 satellite imagery and employs methods such as automated waterbody extraction via mixed index rule sets, field investigation data, Sen + MK trend analysis, mutation analysis, and correlation analysis. Through these techniques, the spatiotemporal variations in SWA in the middle reaches of the Tarim River (MROTR) from 1990–2022 were analyzed, along with the relationships between these variations and vegetation restoration. From 1990–2022, the SWA in the MROTR showed an increasing trend, with an average annual growth rate of 12.47 km² per year. After the implementation of ecological gates water regulations, the SWA significantly increased, with an average annual growth rate of 28.8 km² per year, while the ineffective overflow within 8 km of the riverbank notably decreased. The NDVI in the MROTR exhibited an upward trend, with a significant increase in vegetation on the northern bank after ecological sluice water regulation. This intervention also mitigated the downward trend of the medium and high vegetation coverage types. The SWA showed a highly significant negative correlation with low-coverage vegetation within a 5-km range of the river channel in the same year and a significant positive correlation with high-coverage vegetation within a 15-km range. The lag effect of SWA influenced the growth of medium- and high-coverage vegetation. These findings demonstrated that the large increase in SWA induced by ecological gate water regulation positively impacted vegetation restoration. This study provides a scientific basis for water resource regulation and vegetation restoration in arid regions globally.