Search Results (116)

Watershed ecosystem resilience (RES) plays a vital role in supporting ecosystem sustainability. However, comprehensive assessments and investigations into the complex mechanisms driving RES remain limited, particularly in ecologically sensitive basins. To address this gap, this study proposes a multidimensional RES evaluation framework tailored to watershed-specific natural characteristics. The framework integrates five core dimensions: ecosystem resistance, ecosystem recovery capacity, ecosystem adaptability, ecosystem services, and ecosystem vitality. RES patterns under 2030 different future scenarios were simulated using the PLUS model combined with CMIP6 climate projections. Spatial and temporal dynamics of RES from 2010 to 2020 were quantified using Geodetector and Partial Least Squares Path Modeling, offering insights into the interactions among natural and anthropogenic drivers. The results reveal that RES in the Upper Yangtze River Basin exhibits a spatial gradient of “high in the east and west, low in the middle” with an overall 2.80% decline during the study period. Vegetation coverage and temperature emerged as dominant natural drivers, while land use change exerted significant indirect effects by altering ecological processes. This study emphasizes the importance of integrated land-climate strategies and offers valuable guidance for enhancing RES and supporting sustainable watershed management in the context of global environmental change. Full article

In recent years, under the influence of climate change and human activities, droughts and floods have occurred frequently in the Yangtze River Basin (YRB), seriously threatening socioeconomic development and ecological security. The topography and climate of the YRB are complex, so it is crucial to develop appropriate drought and flood policies based on the drought and flood characteristics of different sub-basins. This study calculated the water storage deficit index (WSDI) based on the Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow On (GFO) mascon model, extended WSDI to the bidirectional monitoring of droughts and floods in the YRB, and verified the reliability of WSDI in monitoring hydrological events through historical documented events. Combined with the wavelet method, it revealed the heterogeneity of climate responses in the three sub-basins of the upper, middle, and lower reaches. The results showed the following. (1) Compared and verified with the Standardized Precipitation Evapotranspiration Index (SPEI), self-calibrating Palmer Drought Severity Index (scPDSI), and documented events, WSDI overcame the limitations of traditional indices and had higher reliability. A total of 21 drought events and 18 flood events were identified in the three sub-basins, with the lowest frequency of drought and flood events in the upper reaches. (2) Most areas of the YRB showed different degrees of wetting on the monthly and seasonal scales, and the slowest trend of wetting was in the lower reaches of the YRB. (3) The degree of influence of teleconnection factors in the upper, middle, and lower reaches of the YRB had gradually increased over time, and, in particular, El Niño Southern Oscillation (ENSO) had a significant impact on the droughts and floods. This study provided a new basis for the early warning of droughts and floods in different sub-basins of the YRB. Full article

Freshwater fish is facing a great crisis due to the looming threat of biodiversity loss. Certain important target areas are difficult to survey owing to their accessibility, making them susceptible to data deficiencies. In this study, we surveyed 52 sites using environmental DNA techniques to investigate fish biodiversity in the Chishui River Basin of the Yangtze River, China. A total of 96,031 valid fish sequences were read, resulting in the identification of 77 species belonging to six orders, 62 genera, and 18 families. The dominant orders were Cypriniformes, Siluriformes, and Perciformes. Among the identified fishes, 71 were native and six were exotic, with the native fishes including 16 endemic fishes from the upper reaches of the Yangtze River. The Shannon–Wiener and richness indices of the tributaries in the upstream section were significantly higher than those of the tributaries in the downstream section. The Datong River is the most diverse secondary tributary of the Chishui River. Among the environmental factors in the Chishui River Basin, altitude and electrical conductivity had the greatest influence on fish diversity (p < 0.01). Our findings highlight the application of environmental DNA technology to modern biodiversity surveys and illustrate that the Chishui River Basin is primarily affected by environmental factors at this stage. However, continuing efforts are needed to protect freshwater biodiversity, and additional research is required to better understand the complex interplay between human activity and environmental factors. Full article

As a pivotal ecological–economic nexus in China, the Yangtze River Basin (YRB)’s spatiotemporal evolution of habitat quality (HQ) profoundly influences regional sustainable development. This study establishes a tripartite analytical framework integrating remote sensing big data, socioeconomic datasets, and ecological modeling. By coupling the InVEST and PLUS models with Theil–Sen median trend analysis and Mann–Kendall tests, we systematically assessed HQ spatial heterogeneity across the basin during 2000–2020 and projected trends under 2030 scenarios (natural development (S1), cropland protection (S2), and ecological conservation (S3)). Key findings reveal that basin-wide HQ remained stable (0.599–0.606) but exhibited marked spatial disparities, demonstrating a “high-middle reach (0.636–0.649), low upper/lower reach” pattern. Urbanized downstream areas recorded the minimum HQ (0.478–0.515), primarily due to landscape fragmentation from peri-urban expansion and transportation infrastructure. Trend analysis showed that coefficient of variation (CV) values ranged from 0.350 to 2.72 (mean = 0.768), indicating relative stability but significant spatial variability. While 76.98% of areas showed no significant HQ changes, 15.83% experienced declines (3.56% with significant degradation, p < 0.05) concentrated in urban agglomerations (e.g., the Wuhan Metropolitan Area, the Yangtze River Delta). Only 7.18% exhibited an HQ improvement, predominantly in snowmelt-affected Qinghai–Tibet Plateau regions, with merely 0.95% showing a significant enhancement. Multi-scenario projections align with Theil–Sen trends, predicting HQ declines across all scenarios. S3 curbs decline to 0.33% (HQ = 0.597), outperforming S1 (1.07%) and S2 (1.15%). Nevertheless, downstream areas remain high-risk (S3 HQ = 0.476). This study elucidated compound drivers of urbanization, agricultural encroachment, and climate change, proposing a synergistic “zoning regulation–corridor restoration–cross-regional compensation” pathway. These findings provide scientific support for balancing ecological protection and high-quality development in the Yangtze Economic Belt, while offering systematic solutions for the sustainable governance of global mega-basins. Full article

As an important ecological barrier in the upper reaches of the Yangtze River, the Jialing River Basin has complex and sensitive hydrochemical evolutionary mechanisms due to its geological structures and human activities. This study focuses on the groundwater in the Wusheng section of the Jialing River Basin, combining field investigations and Entropy-Weighted Water Quality Index (EWQI) calculations to analyze its hydrochemical characteristics and influencing factors and conduct a water quality assessment. The results show that this regional water body has a pH of 7.05–8.36, presenting weakly alkaline and low-mineralization characteristics, with differences in hydrochemical components between groundwater and surface water. The ions are predominantly controlled by rock weathering, with reactions such as halite and gypsum dissolution occurring during groundwater runoff. Groundwater in the tectonic influence zone exhibits abnormal chemical compositions due to lateral recharge from different strata along fracture channels and long-distance runoff reactions with the surrounding rocks. EWQI values for groundwater range from 6.07 to 104.02, with an average value of 37.46, generally exhibiting a trend of increasing EWQI values near the Jialing Riverbank. In this area, 96.15% of groundwater meets excellent or good quality standards and is suitable for direct drinking. The influence of the intensity of different indicators on groundwater quality decreases in the order of Ca²⁺ > Cl⁻ > Mg²⁺ > SO₄²⁻ > HCO₃⁻ > NO₃⁻. Water quality is primarily influenced by the primary geological background, while agricultural practices may also lead to its deterioration. Full article

The construction and operation of reservoirs have significantly altered the downstream flow regime, and the flood regional composition (FRC) method has been widely used to estimate design flood considering the regulation impact of upstream cascade reservoirs. This paper proposes a novel flood regional composition based on the proper orthogonal decomposition (FRC-POD) method that comprehensively takes into account typical-year flood differences and the multi-site flood source characteristics. The proposed method is applied at Cuntan hydrologic station in the upper Yangtze River and compared with the typical-year flood composition (TYFC) method and the most likely flood regional composition (MLFRC) method. The results show the following: (1) The proposed FRC-POD method can identify main flood sources in the design section and pay more attention to floods from the mainstream and the uncontrolled interval basin. (2) Compared with the originally designed values, the 1000-year design peak discharge and 3 d, 7 d, and 15 d flood volumes estimated by the FRC-POD method are decreased by 41.3%, 40.2%, 36.6%, and 34.7%, respectively. (3) Current FRC methods depend on the selected typical-year flood events and have several solutions, while the proposed method has only one final solution, which is more reasonable in practical application. (4) A comparative study proves that the FRC-POD method could obtain rational design flood estimation and is worth further study. Full article

Analyzing drought evolution requires dynamic three-dimensional methods to capture spatiotemporal continuity. Existing approaches oversimplify drought patch connectivity by relying on overlapping logic, thereby neglecting dynamic evolution. We propose a novel three-dimensional identification method incorporating spatial autocorrelation and anisotropy. Using the ERA5 dataset and the multi-model ensemble mean (MEM) of CMIP6, we investigate meteorological drought characteristics and migration patterns in China during 1961–2010 (historical) and 2031–2080 (future, SSP2-4.5/SSP5-8.5). Results indicate future drought frequency may decline by over 70% compared to historical levels, but severity, duration, affected area, and migration distance could increase significantly. Most future droughts (96.3% for SSP2-4.5; 95.0% for SSP5-8.5) are projected in spring and summer. Drought trajectories may predominantly shift northeastward (33% for SSP2-4.5; 38% for SSP5-8.5), with migration hotspots transitioning from the upper Yangtze River Basin to the upper Yellow River Basin. These findings enhance the understanding of drought dynamics and support the development of improved drought monitoring frameworks. The methodology and projections provide critical insights for drought risk management and adaptive water resource planning under climate change. Full article

Accurate simulation and forecast for soil processes has always been a challenge for river management and environmental conservation. However, the sediment modeling technique remains insufficient for catchments characterized by special soil erosion conditions, especially for the steep area of the upper Yangtze River basin. This study presents a framework that incorporates soil erosion and transport calculation modules into a distributed hydrological model, and customized modifications are applied to fit the catchment conditions. In addition, to accurately describe the topography (e.g., slope length and steepness) and to account for its impact on soil process simulation, the sub-basin with high sediment yield is discretized with a higher spatial resolution. The presented is validated in Heishuihe River basin in southwestern China. And the results show that the modified version of the DDRM model (i.e., DDRM-SED) model show a good simulation performance in terms of flow and sediment processes. In addition, the DDRM-SED model with multi-spatial resolution show a better simulation performance than the model with constant spatial resolution. Full article

Accurately predicting the vegetation index (VI) of the Yangtze River Basin and analyzing its spatiotemporal trends are essential for assessing vegetation dynamics and providing recommendations for environmental resource management in the region. This study selected the key climate factors most strongly correlated with three vegetation indexes (VI): the Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), and kernel Normalized Difference Vegetation Index (kNDVI). Historical VI and climate data (2001–2020) were used to train, validate, and test a CNN-BiLSTM-AM deep learning model, which integrates the strengths of Convolutional Neural Networks (CNN), Bidirectional Long Short-Term Memory (BiLSTM), and Attention Mechanism (AM). The performance of this model was compared with CNN-BiLSTM, LSTM, and BiLSTM-AM models to validate its superiority in predicting the VI. Finally, climate simulation data under three Shared Socioeconomic Pathway (SSP) scenarios (SSP1-1.9, SSP2-4.5, and SSP5-8.5) were used as inputs to the CNN-BiLSTM-AM model to predict the VI for the next 20 years (2021–2040), aiming to analyze spatiotemporal trends. The results showed the following: (1) Temperature, precipitation, and evapotranspiration had the highest correlation with VI data and were used as inputs to the time series VI model. (2) The CNN-BiLSTM-AM model combined with the EVI achieved the best performance (R² = 0.981, RMSE = 0.022, MAE = 0.019). (3) Under all three scenarios, the EVI over the next 20 years showed an upward trend compared to the previous 20 years, with the most significant growth observed under SSP5-8.5. Vegetation in the source region and the western part of the upper reaches increased slowly, while significant increases were observed in the eastern part of the upper reaches, middle reaches, lower reaches, and estuary. The analysis of the predicted EVI time series indicates that the vegetation growth conditions in the Yangtze River Basin will continue to improve over the next 20 years. Full article

The Yangtze River fishing ban policy is one of the most important ecological protection measures in middle and upper reaches of Yangtze River. Research on fishers’ satisfaction with the ban will allow policymakers to improve and further optimize it. Based on the theoretical framework of sustainable livelihoods, policy cognition variables are used to explore how livelihood capital and policy cognition differences bring about satisfaction disparities. The research area includes three counties and cities in the Chishui River basin of Guizhou Province, together with Honghu City of Hubei Province, which were among the first areas of the country to implement this policy. The ordered probit model and structural equation model were applied and analyzed based on data that were collected through interviewing the fishers affected by the ban. The results indicate the following: (1) Physical capital, human capital, financial capital, and social capital are significantly and positively correlated with fishers’ satisfaction regarding the Yangtze River fishing ban. In contrast, natural capital does not significantly impact satisfaction. (2) Livelihood capital types have different impacts on the satisfaction of fishers regarding policies for the last aspects. The influence order has the following sequence: financial capital, physical capital, human capital, and social capital. (3) Enhancing fishers’ understanding of the ban could enhance their satisfaction with it. While formulating compensation policies, the government should comprehensively consider the impacts of livelihood capital, formulate special policies to perfect legislation and social security, and use more effective public relations strategies to raise fishers’ awareness of withdrawal policies. Notably, the selected variables and methods in this paper have the potential to significantly enhance the existing literature in the field of ecological management. Full article

Ecosystem services (ESs) are increasingly recognized as critical to sustainable development and human well-being and are frequently used as indicators in environmental governance policies. However, existing studies mostly assess the performance of isolated single ESs, ignoring the management data needs of local governments for comprehensive gate-keeping and the easy monitoring of regional ecosystems, and lacking holistic gate-keeping indicators for local ESs. To address these shortcomings, this study assessed the spatial changes in five main ESs in the Yangtze River basin (YTRB) in China by creating a comprehensive ESs indicator (CESI) using multi-source data, and introduced the hotspot analyses and spatial econometric models to explore the driving forces of CESI. Results showed that during the study period, the CESI in the YTRB increased from 0.44 in 2000 to 0.47 in 2020. High-value areas were mainly concentrated in the hilly and mountainous regions, whereas the low-value areas were predominantly situated in the plain areas. From 2000 to 2020, the hot spots of CESI were primarily located in the middle and the lower reaches of the YTRB. Conversely, the cold spots were situated in the upper reaches of the YTRB. The regression analysis revealed a significant negative association between socioeconomic factors and CESI, while a significant positive association between natural background factors and CESI. Of the natural background factors, average precipitation has the largest positive effect on CESI, with each 1% increase resulting in up to 0.369% increase in CESI. In contrast, GDP density had the greatest negative impact on CESI, with each 1% increase triggering a reduction in CESI of up to 6.210%. The findings suggest that CESI, which integrates multiple ESs, can effectively simplify the difficulty of regional ecological regulation. The driving mechanism indicates that environmental protection policies, when combined with the natural conditions and intensity of human activities in the region, would be more coherent with varying regulatory intensities. Full article

The Yangtze River Basin serves as a vital ecological barrier in China, with its water conservation function playing a critical role in maintaining regional ecological balance and water resource security. This study takes the Minjiang River Basin (MRB) as a case study, employing fractal theory in combination with the InVEST model and the SWAT-BiLSTM model to conduct an in-depth analysis of the spatiotemporal patterns of regional water conservation. The research aims to uncover the relationship between the spatiotemporal dynamics of watershed water conservation capacity and its ecosystem service functions, providing a scientific basis for watershed ecological protection and management. Firstly, fractal theory is introduced to quantify the complexity and spatial heterogeneity of natural factors such as terrain, vegetation, and precipitation in the Minjiang River Basin. Using the InVEST model, the study evaluates the water conservation service functions of the research area, identifying key water conservation zones and their spatiotemporal variations. Additionally, the SWAT-BiLSTM model is employed to simulate the hydrological processes of the basin, particularly the impact of nonlinear meteorological variables on hydrological responses, aiming to enhance the accuracy and reliability of model predictions. At the annual scale, it achieved NSE and R² values of 0.85 during calibration and 0.90 during validation. At the seasonal scale, these values increased to 0.91 and 0.93, and at the monthly scale, reached 0.94 and 0.93. The model showed low errors (RMSE, RSR, RB). The findings indicate significant spatial differences in the water conservation capacity of the Minjiang River Basin, with the upper and middle mountainous regions serving as the primary water conservation areas, whereas the downstream plains exhibit relatively lower capacity. Precipitation, terrain slope, and vegetation cover are identified as the main natural factors affecting water conservation functions, with changes in vegetation cover having a notable regulatory effect on water conservation capacity. Fractal dimension analysis reveals a distinct spatial complexity in the ecosystem structure of the study area, which partially explains the geographical distribution characteristics of water conservation functions. Furthermore, simulation results based on the SWAT-BiLSTM model show an increasingly significant impact of climate change and human activities on the water conservation functions of the Minjiang River Basin. The frequent occurrence of extreme climate events, in particular, disrupts the hydrological processes of the basin, posing greater challenges for water resource management. Model validation demonstrates that the SWAT model integrated with BiLSTM achieves high accuracy in capturing complex hydrological processes, thereby better supporting decision-makers in formulating scientific water resource management strategies. Full article

Vegetation coverage in the upper reaches of the Yangtze River is very important to the ecological balance in this area, and it also has an impact on the inflow runoff and sediment transport processes of the Three Gorges Reservoir. Based on the normalized vegetation index data (NDVI) with 250 m resolution in the upper reaches of the Yangtze River, annual runoff, sediment transport, land use, meteorology, and other data—and by using the methods of Sen + Mann–Kendall trend analysis, partial correlation analysis, and Hurst index—this paper analyzes the temporal and spatial variation characteristics, driving factors, and the influence on the water and sediment inflow processes of the Three Gorges Reservoir in each sub-basin in the upper reaches of the Yangtze River. The results show that (1) NDVI in the upper Yangtze River showed a fluctuating upward trend from 2001 to 2022, and the overall vegetation cover continued to increase, showing a spatial pattern of low in the west and high in the east. At the same time, the runoff volume of the upper reaches of the Yangtze River did not show a significant upward trend from 2006 to 2022, while the sand transport decreased significantly; (2) Among the NDVI-influencing factors in the upper reaches of the Yangtze River, the area driven by the land use factor accounts for about 43% of the whole study area, followed by precipitation; (3) Precipitation significantly affected runoff, and NDVI was negatively correlated with sand transport in most of the watersheds, suggesting that improved vegetation could help reduce sediment loss. In addition, the future trend of vegetation change was predicted to be dominated by improvement (Hurst > 0.5) based on the Hurst index, which will provide a reference for the NDVI change in the upper Yangtze River and the prediction of sediment inflow to the Three Gorges Reservoir. Full article

Tributaries flowing naturally play an important role in maintaining the biodiversity of aquatic organisms in dammed rivers. The Chishui River is currently the only undeveloped first-level tributary and an important habitat for aquatic organisms in the upper reaches of the Yangtze River. Understanding the distribution of the community structure of macrobenthos in the Chishui River and its influencing factors is crucial for the conservation and restoration of aquatic biodiversity in both the Chishui River and the Yangtze River. This study analyzes the community structure characteristics of macrobenthos in the Chishui River using four indicators, i.e., Margalef richness index, EPT taxon richness (the number of taxa in the pollution-sensitive Ephemeroptera, Plecoptera, and Trichoptera), Simpson dominance index, and Shannon diversity index, examining differences among different types of environmental factors (physical, chemical, and biological) in the upper, middle, and lower reaches. Subsequently, RDA (Redundancy Analysis) is used to analyze the main influencing factors of different types of environmental factors on macrobenthic community structure. VPA (Variance Partitioning Analysis) is employed to assess the relative importance of different types of environmental factors and their joint effects on the characteristics of macrobenthic community structure. The results indicate that physical environmental factors explain 68.7% of the variation in macrobenthic community structure indicators, chemical environmental factors explain 79.3%, and biological environmental factors account for 36.2%. The interaction among chemical, biological, and physical factors is the most significant explanatory variable, accounting for 41.7% of the variation in macrobenthic community structure characteristics. For EPT taxon number and Shannon diversity index, the interaction among chemical, biological, and physical factors is also the most important explanatory variable, accounting for 42.1% and 42.5% of the variation. For the Margalef richness index and Simpson dominance index, the interaction between chemical and physical factors is the most significant, accounting for 45.0% and 85.3% of the variation. Therefore, the impact of multiple environmental factors on aquatic organisms should not be overlooked, and attention should be paid to the contributions of various environmental factors in the conservation of macrobenthos in the Chishui River Basin. Full article

Seasonal variation information is very important information for reservoir operation and water resources management. Traditional flood season division relies primarily on statistical methods and does not consider the specific regional rainy patterns. This study used several statistical methods to divide the flood season for the Danjiangkou Reservoir basin in the upper Han River, and verified the results by considering the regional characteristics of the Meiyu and Autumn Rain in the Yangtze River basin. The whole flood season is finally divided into three periods: the summer flood season (20 June to 10 August), a transition period (11 August to 31 August), and the autumn flood season (1 September to 10 October). The Meiyu occurs mainly in June and July, which can produce large floods. The latest end date of the Meiyu is on 8 August, which signals a reduction of flood prevention pressure in the downstream Han River. After 10 August, the Danjiangkou Reservoir flood prevention storage can be released gradually. Autumn Rain occurs from late August to mid-September, and contributes significantly flow discharge, which is an opportunity for reservoir early refill operations. This study will provide a practical approach for flood seasonal division in other regions with seasonal rainfall characteristics. Full article