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In arid regions with scarce water resources, lakes play an extremely vital role in maintaining the ecological environment. Therefore, the Chinese government has launched an ecological water conveyance project in the Tarim River basin in Xinjiang with the aim of restoring the ecological environment of the area. In previous studies, there was no complete evaluation system used to quantify changes in the ecological environment of arid regions after ecological water conveyance. In this paper, Lake Taitema was selected as the study area, which is both a terminal lake in the Tarim River basin and an object of the ecological water conveyance project. This study utilized Landsat TM/OLI satellite remote sensing images and MODIS datasets to build a remote sensing ecological index model and systematically evaluated the changes in the ecological environment and land use types in the Taitema Lake area. A structural equation model was constructed to analyze the correlation between the area of Taitema Lake and its driving factors. The results show that over the selected 20 years, the proportion of pixels with an upward trend (Zc > 0) of the RSEI was 56.5%, while the proportion of pixels with a downward trend (Zc < 0) of the RSEI was 43.5%. The area proportion of regions with poor ecological environment quality decreased by about 40%, and the area proportions of regions with moderate, good, and excellent ecological environment quality increased by 29.7%, 10%, and 0.6%, respectively. By comparing the land use data from 2000 and 2020, the proportion of grassland increased by 6%, the proportion of water area increased by 4.4%, and the proportion of unused land decreased by 9.6%. In summary, after the implementation of the ecological water conveyance project, the ecological environment quality of the Lake Taitema area gradually improved, and ecological water conveyance was the main driving factor of the area change in Lake Taitema.

The overexploitation and misuse of natural resources in oaseshave put a significant strain on the ecosystem’s fragility. Therefore, a rigorous study of the ecological environment’s quality is required to assure the sustainability of oasis growth. The GEE platform has the features of timeliness and large data cloud processing, which accelerating the development of the remote sensing ecological index. The MODIS data of the research region from 2000 to 2020 were uploaded online to the GEE platform in order to calculate the humidity, greenness, dryness, and heat indices for each year. Principal component analysis was then used to develop the remote sensing ecological index after normalization. In addition, Pearson correlation coefficient, Moran’s I index, geo-detector, and the MK trend test were employed to determine the dependability of the RSEI comprehensive index, analyze the ecological environment status and its change trend in the Aksu River Basin from 2000 to 2020, and investigate the external driving factors of RSEI spatial heterogeneity. (1) The average correlation degree of RSEI is as high as 0.820, and the Moran’s I index is larger than 0.9118; thus, its practicability, dependability, and spatial rationality are enhanced. (2) The natural environment quality of Aksu basin is impacted in two ways by human influences. (1) The adoption of ecological protection measures to support the growth of groundwater reserves in the Aksu basin, increase plant covering, and so improve and enhance the ecological environment’s quality. Following the adoption of ecological protection measures, the average RSEI rose by 12.89%, the ecological quality of the farmland-based region improved considerably, and the quality of the ecological environment was enhanced. (2) Urban growth inhibits environmental progress. The acceleration of urbanization and the large rise in NDBSI have exerted pressure on the development of RSEI, while the growth of cities and towns has decreased the vegetation cover in urban areas and impeded the improvement of ecological environment quality. (3) Both human and environmental causes contribute to the regional variability of RSEI in Aksu Basin. The geographical heterogeneity is mostly caused by temperature and land use, with land use being the most important driver. Strengthening research on the connection between groundwater storage change, land use, vegetation cover, and NDBSI may facilitate the growth of regional green economies.

Previous studies have mostly focused on the annual CO2 emissions from drawdown areas on a global scale. However, in drylands, which are more sensitive to global change, finely characterizing the relative importance of drawdown areas on waters (RIDW) in CO2 emissions at the spatio-temporal scale remains unclear. Here, we found that the total drawdown area of drylands could reach 22% of the waters area. From 2004 to 2020, the shrinking of the drawdown area of temperate lakes and reservoirs was the main factor leading to the decline of the total drawdown area. As a result, the mean total CO2 emissions from drawdown areas during 2013-2020 decreased by 18% compared with 2004-2012. The expansion of waters area led to a 29% increase in CO2 emissions from waters. The mean annual CO2 emissions from drawdown areas in drylands was as high as 132.3 ± 23.1 Tg C yr-1, which is equivalent to 61% of estimated CO2 emissions from waters, but its share of CO2 emissions of non-perennial waters shows a significant downward trend. Our study suggests that the spatio-temporal heterogeneity of CO2 emissions caused by the change of drylands waters area is an important part of the global carbon cycle.

Desert riparian vegetation forms an ecological corridor in extremely arid environments, and ecological water conveyance is an important measure of vegetation restoration and biodiversity conservation in desert riparian zones. Studying the responses of vegetation to ecological water conveyance and changes in this process in arid desert riparian zones and assessing the comprehensive benefits of ecological water conveyance are highly significant for ecological conservation and restoration in addition to the formulation of water transfer policies. Previous studies mainly used a single indicator to evaluate the ecological restoration of the mainstream Tarim River in Northwest China; thus, systematic and comprehensive assessments based on multiple indicators have not been conducted. In the present study, remote sensing data and field surveys were used to analyze the ecological restoration status of the Tarim River during 2015–2021 in terms of hydrological responses, vegetation responses, and ecological water conveyance benefits. The results showed that groundwater levels and soil moisture in the mainstream area of the Tarim River increased significantly from 2015 to 2021. The amount of groundwater storage also increased. Ecological water conveyance has created good hydrological conditions for groundwater recharge and ecological restoration on both sides of the mainstream area of the Tarim River. Desert forest ecosystems, mainly comprising Populus euphratica and Tamarix ramosissima, have been saved and rejuvenated in water conveyance areas. After ecological water conveyance, the Simpson and Shannon–Wiener indices increased significantly, but the diversity level began to decline and then stabilize with the increase in water conveyance frequency. The overall habitat status improved and the quality of the ecological environment below the Wusiman section of the middle reaches of the Tarim River improved significantly.