生态 服务 南水北调

The South-to-North Water Diversion Project (SNWD) in China is a trans-basin water transfer project for water resource optimization that affects ecosystem services functions along its main transfer line. Exploring the effects of land-use change on ecosystem services in the headwater and receiving areas along the SNWD is conducive to improving the protection of the surrounding ecological environment. However, previous research lacks a comparative analysis of ecosystem services values (ESVs) in these areas. In this study, the land-use dynamic degree index, land-use transfer matrix, and spatial analysis method were used to comparatively analyze the impact of land-use changes on ESVs in the headwater and receiving areas of the SNWD. The results show that cultivated land was the main land use type in the receiving areas and HAER. From 2000 to 2020, CLUDD in the headwater areas was faster than that in the receiving areas. Spatially, in general, the land-use change areas of the receiving areas were larger. During the study period, cultivated land in the headwater areas of the middle route mainly transferred to water areas and forestry areas, while built-up areas mainly occupied cultivated land in the headwater areas of the east route, receiving areas of the middle route, and receiving areas of the east route. From 2000 to 2020, the ESV increased only in the headwater areas of the middle route, while the ESV in the other three sections decreased. The variation extent of ESV in the receiving areas was greater than that in the headwater areas. The results of this study have important policy significance for land use and ecological protection in the headwater and receiving areas of the SNWD in the future.

Hebi is located in the northern part of China’s Henan Province and is a typical receiving area for China’s South-to-North Water Diversion Project. The assessment of habitat quality and water yield over a long time series is important for evaluating the stability of ecosystem services in Hebi and other receiving areas and for maintaining ecological security and promoting sustainable development. This paper aims to evaluate and dynamically analyse habitat quality and water yield in Hebi, and analyses the characteristics of changes in spatial and temporal patterns of land cover types, habitat quality and water yield in Hebi over the past 20 years, using 2000, 2005, 2010, 2015 and 2020 as horizontal years. The results indicate that: (1) During the study period, the overall land use type in Hebi City has been constantly changing, with the most significant conversion from arable land to other land types; combined with its landscape pattern index, Hebi City has a general characteristic of significant landscape fragmentation and complexity in land use. (2) Habitat quality in Hebi shows an overall trend towards better development, with water availability decreasing and then increasing; the zoning of ecosystem services in Hebi is divided into three classes: superior, good and general, with the area covered by the superior and general classes expanding year by year. (3) Correlation analysis by SPSS software shows that the correlation between habitat quality and landscape pattern index is greater than the correlation between habitat quality and climate change. Additionally, the correlation between water availability and climate change is greater than the correlation between water availability and landscape pattern index.

To ensure water source security and sustainability of the national major strategic project “South-to-North Water Diversion”, this study aims to evaluate the spatio-temporal evolution characteristics of the ecosystem service value (ESV) in its water source area from 2002 to 2022. This study reveals its changing trends and main influencing factors, and thereby provides scientific support for the ecological protection and management of the water source area. Quantitative assessment of the ESV of the region was carried out using the Equivalence Factor Method (EFM), aiming to provide scientific support for ecological protection and resource management decision-making. In the past 20 years, the ESV has shown an upward trend year by year, increasing by 96%. The regions with the highest ESV were Garzê Prefecture and Aba Prefecture, which increased by 130.3% and 60.6%, respectively. The ESV of Xinlong county, Danba county, Rangtang county, and Daofu county increased 4.8 times, 1.5 times, 12.5 times, and 8.9 times, respectively. In the last two decades, arable land has decreased by 91%, while the proportions of bare land and water have decreased by 84% and 91%, respectively. Grassland had the largest proportion. Forests and grasslands, vital for climate regulation, water cycle management, and biodiversity conservation, have expanded by 74% and 43%, respectively. It can be seen from Moran’s I index values that the dataset as a whole showed a slight positive spatial autocorrelation, which increased from −0.041396 to 0.046377. This study reveals the changing trends in ESV and the main influencing factors, and thereby provides scientific support for the ecological protection and management of the water source area.

Inter-basin water transfer (IBWT) projects are an effective means of addressing regional water resource imbalances. However, owing to the long construction cycle, large investment amount, and wide impact range, water diversion projects exhibit delayed and complex benefits, often lacking clear comprehension. In this study, we established a multi-regional comprehensive benefit assessment framework for the IBWT, considering spatiotemporal and multi-dimensional value effects. Using the South-to-North Water Diversion Project (SNWDP) in China as an example, we assessed its comprehensive benefits from 2003 to 2020. The results showed that the comprehensive benefits of the project were USD 207 billion, encompassing economic and ecological benefits, accounting for 71.6% and 28.4%, respectively. In 2020, the benefits of the SNWDP amounted to USD 39.3 billion, with a per-unit area benefit range of USD −1.03 to 4.27. The operation of the SNWDP effectively alleviated groundwater overexploitation in water-receiving areas. However, without the SNWDP, the total loss caused by industrial development limitations due to water scarcity would have been USD 154.3 billion. These results indicate the importance of a practical framework for assessing IWBT project benefits, aiding managers in assessment tasks, and facilitating the prediction and adjustment of project benefits.

… ecosystem service value of the water source area of the central line of the South-to-North water diversion … the sustainable development of the ecosystem in the water source area, along …

… service (VORS)”. The study employs the Invest model to quantitatively assess ecosystem service … changes in EH before and after the water transfer. The research findings indicate that, …

The South-to-North Water Diversion Project, a major project in China, is of great significance to alleviate the shortage of water resources in the north, and the ecological environment in the middle water source area has the most critical impact on water quality safety. As a natural resource and asset, ecosystem services in the water source area of the Middle Route of the South-to-North Water Diversion Project not only provide important resources and services for human beings but also are the necessary basis for the survival and development of other organisms on the earth.As an integral part of the earth’s economy, the value of ecosystem services in the water source area of the Middle Route of the South-to-North Water Diversion Project directly or indirectly contributes to human welfare. Scientific use of land resources can promote the upgrading and transformation of ecosystem services in the water source area of the Middle Route of the South-to-North Water Diversion Project. Based on this, this paper focuses on the impact of land use change on ecosystem services in the water source area of the middle route of South-to-North Water Diversion and its prevention strategies.

… and ecological implications of water-transfer schemes have been … largest water-transfer project in China, the South-to-North Water Diversion (SNWD) Project, to critically review its eco-…

… Due to materials limitation, this article estimated the value of groundwater ecosystem services of the South-to-North Water Transfer Central Project in the Beijing-Tianjin-Hebei receiving …

… , the core water source area of the Middle Route of China’s South–to–North Water Diversion … A regional landscape ecological risk index (ERI) was constructed to evaluate the landscape …

ABSTRACT Large-scale inter-basin water transfer (IBWT) projects fundamentally reshape regional hydrological networks, triggering profound eco-hydrological consequences. This study quantitatively assesses the structural transformation of water networks and their ecohydrological consequences in central and southern Hebei Province, a major recipient area of the Middle Route of China’s South-to-North Water Diversion (SNWD) project. By integrating multi-source remote sensing data, environmental variables, and machine learning techniques, we developed a probabilistic framework to delineate hydrological influence zones and their associated seasonal dynamics before and after the project’s implementation. Utilizing water network density and connectivity indices derived from high-resolution surface water datasets, we quantified changes in network structure across 175 water distribution units. Our findings indicate a 23% increase in water network density and a 26.7% improvement in connectivity, reflecting a substantial enhancement of hydrological integration post-2015. Land use classification models (overall accuracy: 91.7%) identified water network density and soil moisture as primary determinants of ecosystem distribution, with forests and grasslands exhibiting heightened sensitivity to seasonal hydrological variations. The newly constructed artificial water conveyance pathways significantly expanded the spatial extent of ecological influence zones, particularly during the wet season. Probabilistic modeling further revealed distinct environmental preferences among land cover types, and calibrated ecological influence zones closely aligned with existing irrigation district boundaries. These findings underscore the importance of dynamic, data-driven approaches for assessing the ecological consequences of engineered hydrological changes. The proposed framework offers a scalable methodology for evaluating the ecological consequences of IBWT projects, thereby supporting the development of more responsive and ecologically attuned water resource management strategies.

Water scarcity is a significant challenge in China, and the South-to-North Water Diversion Project (SNWDP) aims to address the water deficit in the northern region. This study analyses Landsat 5/7/8 remote sensing imagery from 2001 to 2020 on the Google Earth Engine (GEE) cloud platform to assess the impact of the SNWDP on surface water bodies in water-receiving areas. Moreover, by integrating MODIS evapotranspiration data and ERA5 meteorological reanalysis data, this study comprehensively assesses the SNWDP’s contribution to varied surface water body changes. Using an improved multi-temporal water frequency method, this study extracts max, seasonal, and year-long water surface areas. The results reveal that Beijing and Henan provinces have experienced significant increases in water surface areas post-SNWDP, with their max water surface area growing at a rate of 10.42 km2/yr and 33.49 km2/year, respectively. However, water surface areas in several provinces, especially those along the east route, were not observed to increase. The spatially detailed Mann–Kendall test indicates that the expansion of year-long water bodies is mostly concentrated near the central route project, revealing spatial heterogeneity in the water replenishment effect. Cropland and impervious surfaces are the main contributors to transfers in and out of water bodies. Meteorological and water use factors for spatial variations in water changes are also identified. These findings provide insights into the varied hydrological consequences of the SNWDP and contribute to the evaluation and management of similar large-scale water diversion projects around the world.

… ecosystem service … ecosystem service values across different land use types for each subject, revealing distinct patterns: in the upstream water source region of the Hanjiang River, the …

The Danjiangkou Reservoir (DJKR) serves as the water source for the Middle Route of the South-to-North Water Diversion Project (MR-SNWDP), yet comprehensive understanding of its ecosystem structure and function remains limited. This study addressed this knowledge limitation by developing an Ecopath model with 22 functional groups, parameterized using field survey data from 2022 to 2023. Our findings revealed a trophic structure spanning levels 1 to 3.59, with the highest level occupied by piscivorous mandarin fish (Siniperca spp.). Energy flowed through two dominant pathways, with the grazing food chain demonstrating higher transfer efficiency compared to the detrital pathway. Mixed trophic impact analysis identified the introduced icefish (Neosalanx taihuensis) as exerting substantial negative impacts on most functional groups. Key ecosystem indices, including the total primary production to total respiration ratio (TPP/TR, 1.99), connectance index (CI, 0.248), and system omnivory index (SOI, 0.113), collectively indicated an ecosystem of moderate maturity and stability. Persistent challenges include the proliferation of N. taihuensis, suboptimal energy transfer between trophic levels III and IV, and inefficient utilization of primary productivity. To enhance ecosystem resilience and maintain water quality, we recommend the targeted removal of icefish and strategic management of zooplanktivorous fish populations.

… assessment of ESV in ecological water replenishment areas. With the opening of the South-to-North Water Diversion … on the value of ecosystem services in ecological recharge areas …

Inter-basin water transfer projects (IBWT) are a key strategy for alleviating regional water shortages. However, studies on the long-term effects of such projects on ecosystem services (ESs) in water source areas, as well as their spatiotemporal evolution, remain insufficient. In particular, the specific impacts of the entire project lifecycle (project initiation, dam heightening, project operation, and ecological restoration) on ESs need further exploration. This study focuses on the Middle Route of the South-to-North Water Diversion Project in China, utilizing multi-source datasets (land use and land cover, meteorological data, soil texture, digital elevation models, normalized difference vegetation index, and net primary productivity), applying the biophysical model method to examine the spatiotemporal variations in ESs across the Hanjiang River Basin over the past three decades, and investigates the impact of IBWT on the ESs of water source areas. The findings reveal: (1) During the project initiation phase (2000–2010), vegetation restoration strategies enhanced soil retention by over 60%, demonstrating that simultaneous project-ecological implementation can mitigate habitat degradation risks. (2) The dam heightening phase (2005–2010) drove spatial reconfiguration of water-energy fluxes, leading to declines in water conservation and carbon sequestration in the midstream region, while enhancing flood mitigation and climate regulation in the reservoir area, unveiling the reshaping mechanisms of dam heightening on ESs supply patterns. (3) The operation phase exhibited significant temporal heterogeneity: initial operation (2010–2015) saw a sharp decline in water conservation (>40%) and soil retention (>60%) due to hydrological disturbances, whereas sustained operation (2015–2020) restored water conservation by nearly 70% and soil retention by over 40% through ecological restoration, alongside a net increase of 14.14% in carbon sequestration, confirming the time-lag compensation effects of restoration measures and the dynamic interplay between ecological restoration and project interventions. This research presents empirical evidence supporting the sustainable management and ecological restoration of IBWT, emphasizing the need to balance spatial water allocation with ecological conservation.

… on the Soil and Water Assessment Tool (SWAT) model and a constructed total ecosystem services (TES) index, the impacts of IBWT projects on recipient basin ecosystem services were …

… , and a value assessment model to simulate … South-to-North Water Diversion Project (MRSNWDP) in China. The results reveal significant trade-offs among these service values: water …

… resource management and aquatic ecosystem protection. The paper took the … route source areas (WRSA) of the South-to-North Water Diversion Project (SNWDP) as the research region…

Ecological security has important influence on regional sustainable development. The ecological security of Nanyang, the water source area of the Middle Route of South-to-North Water Diversion Project, was threatened because of surface water pollution. The existing studies had not been able to comprehensively assess the ecological security and future trend of water source area. In order to promote the high-quality development of the follow-up projects of the South-to-North Water Diversion project, it is very important to probe into the current situation and predict the future trend of ecological security in the water source area. Therefore, this paper constructed an ecological security evaluation index system based on the Driving force, Pressure, State, Impact and Response (DPSIR) model, used the combination of Analytic Hierarchy Process and- entropy weighting method to evaluate the ecological security of each district and county in Nanyang from 2000 to 2020, and used the auto regressive integrated moving average (ARIMA) model to predict the ecological security of the water source area from 2021 to 2030. The results demonstrated that: (1) The ecological security of Nanyang had changed from a moderate warning to a general safety, and the ecological security index had improved. The ecological security level of Nanyang would improve continuously from 2021 to 2030. (2) The northwest area and the central area of Nanyang had better ecological security states, while the southeast area wasn't so. Based on the results, the countermeasures for improving ecological security were proposed.

… River Basins. Drought risk peaked in 2006, with ecosystem resilience playing a significant role in … effects among driving factors on drought risk in the water source area of WR-SNWDP. …

… This study proposed the critical points of impact of the middle route of China's South-to-North Water Diversion project (SNWD) on grain water use in 19 counties and cities in the middle …

This study investigates the impacts of China's South‐to‐North Water Transfer Project (SNWTP) on agricultural production using city‐level data from 2009 to 2019. Utilizing the Synthetic Control Difference‐in‐Differences method, we find heterogeneous impacts along the eastern and middle routes of the SNWTP. The operation of the eastern route increases agricultural output by 3.7%, primarily driven by an increase in fishery and aquaculture output. In contrast, the middle route decreases agricultural output by 10.8%, mainly due to the reduction in outputs of crop cultivation and animal husbandry. This unexpected decrease in agricultural output in the water‐receiving cities along the middle route can be attributed to the stricter environmental regulations aimed at preserving the quality of the diverted water. The heterogenous effects of the SNWTP on agricultural production highlight the complex consequences of large‐scale water infrastructure projects, underscoring the importance of incorporating environmental considerations into the evaluation of such initiatives.

… are known to profoundly modify the ecological structure of aquatic systems, however, comparative studies assessing the ecological impacts on transferred versus non-transferred water …

… the impact of the Western Route of the South-to-North Water Diversion Project (Phase Ⅰ) on the hydrology and water resources, ecological environment, and social economy of water …

The South-to-North Water Diversion Western Route Project area includes fragile ecological areas.Mitigating the project's ecological impacts is one of the key concerns influencing the feasibility of the project.This article illustrates the need for research on the ecological impacts of water diversion in the Western Route Project.It identifies key scientific concerns related to the adaptive regulation of water diversion thresholds and disturbances for the new situation.This study developed a general research framework for assessing and addressing the ecological impacts of the Western Route Project, and proposes key research areas.They include investigating the coordinated evolution mechanism of water resources, water ecology, and economic society in the water source area and developing assessment methods and dynamic allocation techniques for ecological water demand in the water source area, water resource endowments and adjustable water thresholds under changing environments.It also includes ecological compensation mechanisms for water diversion, biological risk invasion analysis, and a comprehensive assessment and optimization of the water diversion impacts from a systematic perspective.The South-to-North Water Diversion Western Route Project must properly coordinate the potential conflicts between the water diversion projects and their ecological protection, adhering to the principle of ecological priority, to ensure that the comprehensive benefits are shared equally between the water source area and the water receiving area.

… , inter‑sectoral links, and the implications of evolving water use. This study developed a multi… shifts reshape industrial water demand and influence regional water resource sustainability. …

The South-to-North Water Diversion Project (SNWDP), the world’s largest water transfer initiative, is designed to address northern China’s acute water scarcity by diverting approximately 45 km3 of water annually from the south through three major routes, with completion targeted for 2050. This review demonstrates that the SNWDP has already improved water security for over 150 million people, stabilized groundwater, and supported agricultural and urban development, but also presents significant challenges, including escalating costs, large-scale resettlement, and substantial environmental concerns such as ecosystem alteration, salinity intrusion, pollutant transfer, and risks to biodiversity and water quality. While mitigation and adaptive management efforts are ongoing, their long-term effectiveness remains uncertain. Notably, the SNWDP’s influence extends beyond China: by enhancing food production self-sufficiency, it can help stabilize global food markets during concurrent droughts and serves as a model—albeit a debated one—for large-scale water management and governance. The project’s hydropolitical and geopolitical dimensions, especially regarding the planned western route and potential transboundary impacts, underscore the need for international dialog and monitoring. Overall, the SNWDP exemplifies both the opportunities and dilemmas of 21st-century megaprojects, with its legacy dependent on balancing economic, environmental, and social trade-offs and on transparent, participatory governance to ensure sustainable outcomes for China and the global community.

To effectively improve the water quality of the Bai River, this paper proposes the use of the ecological replenishment of the South–North Water Transfer as a measure for the integrated allocation of water resources, addressing the impact of complex topography, climate, and human disturbances on the river’s water environment. This measure can alleviate the problem of water shortage and significantly enhance the quality of the Bai River’s water environment. Using the MIKE21 coupled hydrodynamic and water-quality model, this paper analyzes the impact of ecological recharge on river hydrodynamics and simulates the evolution of various water-quality indicators, including dissolved oxygen (DO), permanganate index (CODMn), chemical oxygen demand (COD), ammonia nitrogen (NH3-N), and total phosphorus (TP) under different scenarios. The aim of this paper is to investigate the impact mechanism of ecological recharge on the river’s water environment. The results show that the most significant improvement in river water quality is achieved when the recharge flow is 2Q and the recharge duration is 1/2T (scenario 1), with the river improving from a grade IV water-quality standard to a grade III water-quality standard, and COD and TP indicators improving to a grade II water standard, with the largest improvement rate of 94.67% seen in DO, with the best improvement rate of 94.67% in DO indicators and the best reduction rate of 66.67% in TP indicators. Overall, ecological replenishment can significantly improve the Bai River’s water quality, with scenario 1 being the most effective approach. The results of this study may provide theoretical and technical support for the future management of river water environments.

… This study aimed to comprehensively assess the long-term environmental impacts of the MR… and LST, to construct a comprehensive impact assessment framework, as shown in Figure …

… of the South-to-North Water Diversion Project, … used to analyze the intensity of LST changes, and the intensity of temperature changes in the Middle Route of the South-to-North Water …

… temporal changes in water quality within … of diverted water on the water quality of beneficiary lakes and reservoirs before and after water diversion by the South-to-North Water Diversion …

Water-use efficiency (WUE) and carbon-use efficiency (CUE) are critical indicators of ecosystem function and hydrologic processes, reflecting the water-carbon flux exchange rate. Climatic variables, land use and land cover change (LUCC) and water diversion project (WDP) have altered water-carbon cycle; however, their roles in modulating WUE and CUE remain uncertain. To explore these effects, a framework is proposed and Han River basin (HRB) in China is selected as a case study including the data sets from both remote sensing and in situ observations during 2000-2020. The process-based Regional Hydro-Ecological Simulation System model and a supervised machine learning model are applied to simulate the impacts of climatic variables, LUCC and WDP on WUE and CUE, which are conducted by designing four experiments. We find that no significant WUE and CUE trends attributed to contrasting trends in the dry (October to March) and wet (April to September) seasons. Temperature variations greatly affect WUE and CUE, with WUE decreasing in the wet season and increasing in the dry season due to minimum temperature changes. LUCC has litter impacts on WUE and CUE changes. From 2014 to 2020, the middle route of the South-to-North WDP decreased WUE by 0.22 gCkg-1H2O in the middle-low HRB's wet season, slightly affecting CUE. Seasonal CUE was stable, with the largest decrease of 0.04 in the upper HRB during the wet season. The WDP also increased WUE sensitivities to minimum and maximum temperatures, while CUE sensitivities remained constant. Our case study has proven that the proposed framework is an effective way to understand the roles of climate change and WDP in modulating WUE and CUE.

As a critical national strategy for water resource allocation currently under planning in China, the implementation of the Western Route of South-to-North Water Diversion Project (WR-…

… resources increases, the construction of diversion projects will … water quality management for similar water diversion projects. … , the spatial DA was used to study the spatial water quality …

The South-to-North Water Division Middle Route Project (MRP) is currently the longest inter-basin water diversion project in the world. It benefits a large population and its water quality has attracted much attention. In this study, seasonal investigations on 11 sampling sites along the MRP were conducted from 2018 to 2019; water temperature, pH, turbidity, transparency, CODMn, dissolved oxygen, total phosphorus, phosphate, total nitrogen, ammonia, nitrate, and chlorophyll a were determined synchronously. Single leakage distance clustering analysis identified the spatio-seasonal heterogeneity of physiochemical parameters. The trophic level index (TLI) and the water quality status were assessed: TLI increased and WQI decreased from south to north; TLI and WQI had seasonal differences (p < 0.001), the best water quality was observed in autumn, and the lowest TLI was observed in winter. The trophic level was “oligotrophic to mesotrophic”; water quality status was “good.” The multiple linear stepwise regression analysis confirmed that total nitrogen (TN), Chl a, and CODMn were the driving factors in water quality. These factors were applied to build the simplified WQI model, which was confirmed as a reliable method of water quality assessment for the MRP and a fitting substitute for TLI and WQI. The results provided support for the water quality evaluation of the MRP.

The Middle Route (MR) of the South to North Water Diversion Project of China (SNWDPC) is one of the most important cross-basin water diversion projects worldwide, leading to substantial attention on the water environment of the project. In order to evaluate the water environment status of the MR of the SNWDPC, the spatiotemporal variations and underlying causes in the water environment along the route are systematically revealed in this study. The data were analyzed using the water quality index (WQI) and Spearman correlation analysis. The results showed annual average WQI values ranging from 91.76 to 92.90 during the period of 2019 to 2022, indicating the water quality status of “excellent.” However, permanganate index (CODMn) was increased along the route ranging from 1.83 mg/L to 2.27 mg/L, which is assumed to be primarily caused by the decomposition of dead planktonic algae. Chlorophyll a (Chl-a) showed significant spatial heterogeneity, increasing along the route with a range of 3.13 µg/L to 8.87 µg/L. The primary reason is the decrease in flow velocity and the increase in pH along the route. In summary, although the overall water environment of the MR of the SNWDPC is of high quality, environmental risks such as the high CODMn and Chl-a concentrations in the end of the route require sufficient attention from the management department. The findings provide guidance for ensuring the safety of water supply in cross-basin water diversion projects.

… Migration of Gravity Center Analysis The gravity model, which is based on the law of universal gravitation, is a spatial data analysis method used to predict migration and flow between …

Impounded lakes are often interconnected in large-scale water diversion projects to form a coordinated system for water allocation and regulation. The alternating runoff and transferred water can significantly impact local ecosystems, which are initially reflected in the sensitive phytoplankton. Nonetheless, limited information is available on the temporal dynamics and assembly patterns of phytoplankton community in impounded lakes responding to continuous and periodic water diversion. Herein, a long-term monitoring from 2013 to 2020 were conducted to systematically investigate the response of phytoplankton community, including its characteristics, stability, and the ecological processes governing community assembly, in representative impounded lakes to the South-to-North Water Diversion Project (SNWDP) in China. In the initial stage of the SNWDP, the phytoplankton diversity indices experienced a decrease during both non-water diversion periods (8.5 %∼21.2 %) and water diversion periods (5.6 %∼12.2 %), implying a disruption in the aquatic ecosystem. But the regular delivery of high-quality water from the Yangtze River gradually increased phytoplankton diversity and mediated ecological assembly processes shifting from stochastic to deterministic. Meanwhile, reduced nutrients restricted the growth of phytoplankton, pushing species to interact more closely to maintain the functionality and stability of the co-occurrence network. The partial least squares path model revealed that ecological process (path coefficient = 0.525, p < 0.01) and interspecies interactions in networks (path coefficient = -0.806, p < 0.01) jointly influenced the keystone and dominant species, ultimately resulting in an improvement in stability (path coefficient = 0.878, p < 0.01). Overall, the phytoplankton communities experienced an evolutionary process from short-term disruption to long-term adaptation, demonstrating resilience and adaptability in response to the challenges posed by the SNWDP. This study revealed the response and adaptation mechanism of phytoplankton communities in impounded lakes to water diversion projects, which is helpful for maintaining the lake ecological health and formulating rational water management strategies.

… , and ecosystem instability. However, the mechanisms governing fish community responses to water transfer … assembly in three water bodies along the East Route of the South-to-North …

Proper diverted water volume has always been the focus of the West Route of South-to-North Water Diversion Project in China. Ecological water demand of water source area is an …

… physiological traits, habitat adaptation strategies, and environmental response patterns, and … of aquatic ecosystems, making them more effective indicators of changes in water quality. …

… , as the transfer reservoir of the South-to-North Water Transfer Central Project, is … South-to-North Water Transfer Central Project will inevitably have an important impact on the ecosystem …

ABSTRACT The South-to-North Water Diversion Project Middle Route (SNWD-MR) annually diverts hundreds of millions of cubic meters of water from the Danjiangkou Reservoir to Beijing, significantly impacting the regional groundwater cycle. To conserve water resources, the government has implemented ecological water replenishment (EWR) in some water systems. This study aimed to study the coupled process of groundwater dynamics and land subsidence (LS) in Yongding River (YDR) basin (Beijing section) following the implementation of the SNWD-MR and EWR. First, an Interferometric Synthetic Aperture Radar (InSAR) time series technique was used to detect spatial and temporal distributions of surface displacement between 2015 and 2020 based on satellite images from Sentinel-1A/B. The results indicated a predominant LS deceleration trend during the InSAR observation period. The area with subsidence velocity below 20 mm/yr decreased significantly by 18.6% after SNWD-MR and EWR (from 2016 to 2020). Then, groundwater level fluctuations during the InSAR observation period were analyzed using groundwater measurement well data. Over 60% of these wells showed a rebound in groundwater levels after the implementation of SNWD-MR and EWR. The polynomial distribution lag model (PDL) revealed the association between LS and groundwater level changes, depicting both short- and long-term lag effect. The results showed significant spatial and temporal heterogeneity on the short- and long-term response between groundwater level change and regional subsidence. In addition, we calculated the differential subsidence slope based on the InSAR-derived LS and analyzed its impact on the river slope after SNWD-MR and EWR. The results show that two sections with significant severe differential subsidence slope occur between 0 and 14,000 m and between 54,000 and 78,000 m along the YDR. The slope change caused by LS may reduce the conveyance capacity of surface canals, and more attention should be paid in those two sections. These findings have an important scientific significance for management strategy for LS control against the background of SNWD-MR and EWR.

Microbial communities, as critical functional components of riverine ecosystems, play a pivotal role in biogeochemical cycles and water quality regulation. The South-to-North Water Diversion Middle Route Project (SNWD-MRP) is a major cross-basin water transfer initiative, and bacteria are essential for the stability of water quality in the project. This study employed environmental DNA (eDNA) metabarcoding targeting the 16S rRNA gene to investigate spatiotemporal variations in water quality and bacterial communities along the SNWD-MRP during summer and winter. Integrated analyses, including redundancy analysis (RDA), Mantel tests, and ecological network modeling, were applied to unravel the driving mechanisms of microbial succession. The water quality along the SNWD-MRP is generally classified as Grade I, with significant seasonal variations in water quality parameters and microbial community composition. In the summer, higher temperatures lead to an increased abundance of cyanobacteria. In contrast, during the winter, lower water temperatures and higher dissolved oxygen levels result in the dominance of Pseudomonas and Bacillota species. RDA identified the permanganate index as the primary driver of microbial composition across seasons, with total phosphorus and total nitrogen having a greater influence in winter. Mantel tests highlighted significant correlations between Cyanobacteria and total phosphorus during winter. Ecological network analysis revealed that the complexity and connectivity of the winter network increased, likely due to suitable nutrient levels rendering the microbial network more complex and stable. These findings underscore the synergistic effects of temperature and nutrient availability on microbial succession, providing actionable insights for optimizing water quality management and ecological stability in large-scale water diversion systems.

The continuous operation of the Three Gorges Reservoir since 2003 has altered the annual runoff into the Changjiang River Estuary, significantly affecting patterns of saltwater intrusion. This has become more pronounced with the development of the East Route of the South-to-North Water Transfer Project, which has changed the runoff distribution and saltwater dynamics once again. Recognizing the critical need to understand these changes, this study employs numerical simulations to investigate the impact of the East Route of the South-to-North Water Transfer Project’s water abstraction on saltwater intrusion in the Changjiang River Estuary post-2003. It assesses intrusion distances, freshwater availability, and periods when water intake might be compromised due to high salinity. Our findings indicate that the East Route of the South-to-North Water Transfer Project markedly influences intrusion patterns. By modeling various runoff scenarios, the study delineates the correlation between average monthly runoff at the Datong Hydrological Survey Station and estuary salinity. It then suggests optimal ecological discharge levels to manage saltwater intrusion effectively. This research provides insights which are necessary for informed water management and ecological protection in the region.

… water quality in SNWDP-ER is satisfactory and meets the Class III requirements in China Environmental Quality Standard for Surface Water… between diversion and non-diversion periods …

Water diversion projects effectively mitigate the uneven distribution of water resources but can also influence aquatic biodiversity and ecosystem functions. Despite their importance, the impacts of such projects on multi-domain microbial community dynamics and the underlying mechanisms remain poorly understood. Utilizing high-throughput sequencing, we investigated bacterial, archaeal, and fungal community dynamics along the eastern route of the South-to-North water diversion project during both non-water diversion period (NWDP) and water diversion period (WDP). Our findings revealed competitive exclusion effects among bacterial and archaeal communities during the WDP, characterized by decreased species richness and increased biomass, while fungal biomass significantly declined. Distance-decay relationships suggested microbial homogenization during the WDP. Robustness analyses revealed reduced community stability during the WDP, with water diversion primarily influencing bacterial stability, while environmental factors had a greater impact on archaeal and fungal communities. Stochastic processes, primarily homogenizing dispersal and drift, intensified for bacterial and fungal communities during the WDP. Notably, only bacterial functional diversity decreased during the WDP, with increased relative abundance of chemoheterotrophic and organic compound catabolic bacteria and declined photoautotrophic bacteria. PLS-PM indicated that water diversion primarily shaped bacterial assembly processes and functional guilds, whereas environmental factors had a greater influence on archaeal communities. This study enhances our understanding of microbial dynamics during the WDP and underscores the importance of assessing both direct impacts and resulting environmental fluctuations.