Search Results (104)

To prevent the occurrence of excavation face instability incidents during shield tunneling, this study takes the Bailuyuan tunnel of the ‘Hanjiang-to-Weihe River Water Diversion Project’ as the engineering background. A three-dimensional discrete element method simulation was employed to analyze the tunneling process, revealing the displacement response of the excavation face to various tunneling parameters. This led to the development of a risk assessment method that considers both tunneling parameters and geological conditions for deep-buried shield tunnels. The above method effectively overcomes the limitations of finite element method (FEM) studies on shield tunneling parameters and, combined with the Analytic Hierarchy Process (AHP), enables rapid tunnel analysis and assessment. The results demonstrate that the displacement of the excavation face in shield tunnel engineering is significantly influenced by factors such as the chamber earth pressure ratio, cutterhead opening rate, cutterhead rotation speed, and tunneling speed. Specifically, variations in the chamber earth pressure ratio have the greatest impact on horizontal displacement, occurring predominantly near the upper center of the tunnel. As the chamber earth pressure ratio decreases, horizontal displacement increases sharply from 12.9 mm to 267.3 mm. Conversely, an increase in the cutterhead opening rate leads to displacement that first rises gradually and then rapidly, from 32.1 mm to 121.1 mm. A weighted index assessment model based on AHP yields a risk level of Grade II, whereas methods from other scholars result in Grade III. By implementing measures such as adjusting the grouting range, cutterhead rotation speed, and tunneling speed, field applications confirm that the risk level remains within acceptable limits, thereby verifying the feasibility of the constructed assessment method. Construction site strategies are proposed, including maintaining a chamber earth pressure ratio greater than 1, tunneling speed not exceeding 30 mm/min, cutterhead rotation speed not exceeding 1.5 rpm, and a synchronous grouting range of 0.15 m. Following implementation, the tunnel construction successfully passed the high-risk section without any incidents. This research offers a decision-making framework for shield TBM operation safety in complex geological environments. Full article

The Qinling Mountains serve as the main water source for the Weihe River and Hanjiang River. However, the lack of sufficient observational data limits a deeper understanding and the utilization of its water resources. In this study, the Variable Infiltration Capacity (VIC) hydrological model is used to quantitatively analyze runoff changes and their impacts on these rivers, based on meteorological, land use, and elevation data. By using the hydrological parameter transplantation method, a parameterized system was established to simulate runoff variations from 1970 to 2020. Results showed that the total runoff of the Qinling Mountains in Shaanxi Province ranged between 13.26 and 44.47 billion m³/year, with an average perennial runoff of 25.05 billion m³/year. Over the past 51 years, the runoff volume has exhibited a slightly decreasing trend. The average runoff at the northern foothills is 3.56 billion m³/year, which accounts for 62.4% of the natural average runoff of the Weihe River (Huaxian Station). In contrast, the average runoff at the southern foothills is 21.49 billion m³/year, which accounts for 68.1% of the natural average runoff of the Hanjiang River (Huangjiagang Station). The significant variation in water vapor transport from the western equatorial Pacific to the region via the South China Sea has been identified as the primary reason for the changes in runoff. This quantitative study of runoff changes in the Qinling Mountains clarifies their influence on the Weihe River and the Hanjiang River and will provide a basis for the rational usage of ecological water. Full article

Land use conflicts represent an increasing challenge to sustainable development, particularly in regions undergoing rapid urbanization. This study investigated the spatiotemporal dynamics of land use conflicts and their ecological implications in Tianshui City from 1980 to 2020. The main objectives were to identify patterns of spatial heterogeneity, explore the driving factors behind these conflicts, and analyze their relationship with the ecological risks. The results indicate the following findings. In terms of spatiotemporal heterogeneity, early land use changes were primarily driven by structural factors, such as topography and climate, with a Nugget/Still ratio of <0.30 observed from 1980 to 2000. After 2000, however, stochastic factors, including an average annual urbanization rate increase of 5.2% and a GDP growth rate of 9.1%, emerged as the dominant drivers, as reflected in a Nugget/Still ratio > 0.36. Regarding conflict intensity, high-conflict areas expanded by approximately 1110 square kilometers between 1980 and 2020, predominantly concentrated in fertile agricultural regions such as the Weihe River Basin and urban core areas. Conversely, non-conflict zones decreased by 38.7%. In terms of ecological risk correlation, bivariate LISA cluster analysis revealed a significant spatial autocorrelation between severe land use conflicts and ecological risks (Moran’s I = 0.62, p < 0.01). High-risk clusters in areas transitioning from arable land to built-up land increased by 23% after 2000. Predictions based on the future land-use simulation (FLUS) model suggest that by 2030, high-intensity conflict areas will expand by an additional 16%, leading to intensified competition for land resources. Therefore, incorporating ecological safety thresholds into land spatial planning policies is essential for reconciling the conflicts between development and conservation, thereby promoting sustainable land use transitions. Full article

Historically, the Wei River has served as part of the Yongji Canal section of the Grand Canal, playing a crucial role in connecting northern and southern China. However, with the acceleration of urbanization in China, issues such as excessive land development and ecological landscape fragmentation have emerged. Exploring the mechanisms of landscape fragmentation evolution in the Wei River basin and proposing optimization strategies is of significant importance for land use and ecological stability within small- to medium-sized river basins. This study selected land use data from the Weihe River basin between 2000 and 2020, using landscape pattern indices to analyze the trend of landscape fragmentation. The principal component analysis (PCA) and geographical detector methods were employed to explore the distribution characteristics and driving factors of landscape fragmentation. The research results indicate that: (1) The degree of landscape fragmentation in the Wei River basin has progressively intensified over time. The edge density index (ED), the landscape division index (DIVISION), the landscape shape index (LSI), and the Shannon diversity index (SHDI) have increased annually, while the contagion index (CONTAG) and area-weighted mean patch size (Area_AM) have continuously decreased; (2) Landscape fragmentation in the Wei River basin is characterized by stable changes in the source and tributary fragmentation areas, a concentrated distribution of fragmentation in the tributaries, and a significant increase in fragmentation in the main stream; (3) The analysis using the geographic detector method indicates that vegetation coverage (FVC), human activity intensity (HAI), and land use/land cover change (LUCC) are the main driving factors of landscape fragmentation in the Wei River basin. The findings explore the mechanisms of landscape fragmentation in the basin and provide a reference for land use planning and ecological restoration in the region. Full article

Groundwater is a vital and invaluable resource on our planet, serving as a critical water supply for human life, industrial activities, and agricultural production. It plays a pivotal role in sustaining human existence and driving societal progress. In this study, we conducted a comprehensive analysis of the hydrochemical characteristics and controlling factors of groundwater in the Upper Weihe River (UWR) using statistical analysis, Piper diagrams, Gibbs diagrams, correlation analysis, and ion ratio analysis. To evaluate the suitability of the regional groundwater for potable use, we employed the entropy weight water quality index (EWQI). Additionally, the sodium adsorption ratio (SAR) and percentage of soluble sodium (Na%) were utilized to evaluate the groundwater’s adaptability to irrigation. Furthermore, this study also assessed the health risks faced by adults and children in the UWR. The findings indicate that the main cations and anions in groundwater are Ca²⁺ and HCO₃⁻, respectively. The hydrochemical types are predominantly HCO₃-Ca, Cl-Ca, and mixed types. The composition of groundwater is primarily influenced by the dissolution of silicate and carbonate minerals, with cation exchange also playing a significant role in shaping its hydrochemical characteristics. The water quality assessment indicates that the majority of groundwater in UWR is classified as “excellent” or “good”, rendering it suitable for human consumption. However, 7.17% of the water samples were of poor quality and unsuitable for drinking; these were primarily located in a few areas in the northern and western parts of the study area. Regarding irrigation, 94.83% of the groundwater is deemed very suitable; however, a small fraction is not appropriate for such use. Additionally, non-carcinogenic risks are generally higher across most parts of the study area for both children and adults, with children exhibiting significantly higher risks than adults. These findings offer crucial insights regarding the sustainable management and environmental conservation of groundwater resources in the UWR. Full article

The wetland ecosystem is one of the most important carbon sinks on Earth, the most biodiverse ecological landscape in nature, and one of the most important living environments for human beings. The Weihe River wetland is located in the Guanzhong Plain urban agglomeration, with extreme climate and urban expansion having a great impact on its dynamic changes. Revealing the characteristics of and trends in wetland dynamics in the Weihe River Basin is the key to protecting and maintaining the healthy development of the Weihe River wetlands. This paper analyzed the changing characteristics of land use types and landscape patterns in the wetlands of the Weihe River Basin using wetland land use data from six periods in the Weihe River wetland from 1980 to 2020 and explored the spatial and temporal distribution characteristics and dynamic changes in wetlands in the Weihe River Basin. The results showed the following: (1) Wetlands in the Weihe River Basin, dominated by rivers, saw area fluctuations with an initial decline followed by an increase. Land use changes followed a slow–fast–slow trend. (2) From 1980 to 2020, frequent conversions among wetland types were observed. The primary transformation was the conversion of marshes into lakes (18.05 km²) and reservoirs/ponds (17.98 km²). Approximately 0.06 km² of lakes were transformed into canals/channels. (3) River patches have the largest area, while canals/channels have the smallest. The patch density (PD) and landscape shape index (LSI) of wetlands fluctuate significantly, and the reduction in area leads to a 3.46% decrease in aggregation index (AI). Shannon’s diversity index (SHDI) has decreased by 5.41%. (4) The centroid of marshes experiences significant changes, while river changes are complex. The centroid changes in reservoirs/ponds are located along the southeast–northwest line. Canals/watercourses remain stable. Lakes exhibit the longest migration. This study provides robust scientific support for wetland ecological protection, policy formulation, and social sustainable development by conducting an in-depth analysis of the dynamic change characteristics of wetlands in the Weihe River Basin. Full article

The riparian ecosystem is highly susceptible to pollution, particularly heavy metals (HMs), due to its unique spatial position and landscape characteristics. Therefore, assessing the risks of HM pollution and identifying potential sources are crucial for formulating effective prevention and control measures. This study investigates the characteristics of HMs (Ni, Cr, Zn, Cd, Cu, Pb) pollution in the Weihe River riparian zone, identifies their sources, and assesses the associated ecological and human health risks. The results indicate that Ni, Zn, and Cd are the primary pollutants in riparian soil, with the average Cd concentration being 5.64 times higher than the background value, indicating a high potential ecological risk. Spatially, the average HM concentrations in the middle and upper reaches are higher than in the lower reaches. Vertically, as the distance from the riparian increases, the HM content exhibits a “U”-shaped pattern (increase-decrease-increase). The Absolute principal components multiple regression (APCS-MLR) receptor model identified four potential pollution sources: traffic sources; agricultural sources; industrial sources; and natural sources. Additionally, the Monte Carlo simulation-based human health risk assessment indicates that the non-carcinogenic health risk indices for all HMs are within acceptable ranges. For carcinogenic health risk indices, there is a 1.14% probability for children. However, the vast majority of the risks fall within acceptable or no-risk categories. Full article

Temporal and spatial changes in non-point source pollution, driven by significant alterations in land use due to increased human activity, have considerably affected the quality of groundwater, surface water, and soil environments in the region. This study examines the Weihe River basin in greater detail, an area heavily impacted by human activity. The study developed the River Section Potential Pollution Index (R-PPI) model using the Potential Non-Point Source Pollution Index (PNPI) model in order to investigate the dynamic changes in River Section Potential Pollution (R-PP) over a 31-year period and its associated risks, especially those related to land use and land cover change (LUCC). The predominant land uses in the Weihe River Basin are cropland, grassland, and forest, making up around 97% of the basin’s total area. The Weihe River Basin underwent a number of soil and water conservation initiatives between 1990 and 2020, which significantly decreased the potential pollution risk in the river segment. The research separated the R-PP risk values in the area into five different categories using a quantile classification technique. According to the data, there is a polarization of R-PP risk in the area, with downstream parts especially having an increased risk of pollution in river segments impacted by human activity. On the other hand, river segments in the middle and upper reaches of the basin showed a discernible decline in possible pollution risk throughout the study period. The Weihe River Basin’s rapid urbanization and land degradation are to blame for the current increase in R-PP risk. The substantial influence of LUCC on the dynamic variations in R-PP risk in the Weihe River Basin is highlighted by this study. Additionally, it offers crucial information for upcoming conservation initiatives and urban planning guidelines meant to enhance the area’s ecological well-being and environmental standards. Full article

Water quality safety in the water source constitutes a crucial guarantee for public health and the ecological environment. This study undertakes a comprehensive assessment of the water quality conditions within the Jing River Basin of the Loess Plateau, emphasizing the spatial and temporal characteristics, as well as the determinants influencing surface water quality in the Shaanxi section. We utilized data from seven monitoring stations collected between 2016 and 2022, employing an enhanced comprehensive Water Quality Index (WQI) method, redundancy analysis (RDA), and Spearman’s correlation analysis. The results show that the average annual WQI value of the water quality of the Shaanxi section of the Jing River increased from 68.01 in 2016 to 76.18 in 2022, and the river’s water quality has gradually improved, with a significant improvement beginning in 2018, and a series of water quality management policies implemented by Shaanxi Province is the primary reason for the improvement. The river’s water quality has deteriorated slightly in recent years, necessitating stricter supervision of the coal mining industry in the upper section. The river has an average WQI value of 73.70 and is rated as ‘good’. The main pollution indicators influencing the river’s water quality are COD_Mn, COD, BOD₅, NH₃-N, and TP. From the upstream to the downstream, the water quality of the river shows a pattern of increasing and then decreasing, among which S4 (Linjing Bridge in Taiping Town) and S5 (Jinghe Bridge) have the best water quality. The downstream part (S6, S7) of the Jing River near the Weihe River has poor water quality, which is mostly caused by nonpoint source contamination from livestock and poultry rearing, agricultural activities, and sewage discharge. Redundancy analysis revealed that the spatial scale of the 2500 m buffer zone best explained water quality changes, and the amount of bare land and arable land in land use categories was the key influencing factor of river water quality. Full article

Automated water body (WB) extraction is one of the hot research topics in the field of remote sensing image processing. To address the challenges of over-extraction and incomplete extraction in complex water scenes, we propose an encoder–decoder architecture semantic segmentation network for high-precision extraction of WBs called EDWNet. We integrate the Cross-layer Feature Fusion (CFF) module to solve difficulties in segmentation of WB edges, utilizing the Global Attention Mechanism (GAM) module to reduce information diffusion, and combining with the Deep Attention Module (DAM) module to enhance the model’s global perception ability and refine WB features. Additionally, an auxiliary head is incorporated to optimize the model’s learning process. In addition, we analyze the feature importance of bands 2 to 7 in Landsat 8 OLI images, constructing a band combination (RGB 763) suitable for algorithm’s WB extraction. When we compare EDWNet with various other semantic segmentation networks, the results on the test dataset show that EDWNet has the highest accuracy. EDWNet is applied to accurately extract WBs in the Weihe River basin from 2013 to 2021, and we quantitatively analyzed the area changes of the WBs during this period and their causes. The results show that EDWNet is suitable for WB extraction in complex scenes and demonstrates great potential in long time-series and large-scale WB extraction. Full article

Droughts in the Weihe River Basin are occurring more frequently and are becoming more intense. These events negatively affect industrial production, economic development, and ecosystems. Studying how vegetation changes in response to them is of practical significance. We report temporal and spatial trends in vegetation cover, use a copula function to analyze relationships between drought and vegetation cover, and assess the probability of vegetation loss in different drought scenarios. A vegetation index trends upwards from north to south in this basin; from 2001 to 2017, vegetation cover also trends upward in most areas, although it decreases in areas with high vegetation cover. An escalated susceptibility to drought has been observed in the southern and eastern sectors, where proximity to the riverbank correlates with heightened drought sensitivity, particularly in zones of intensified vegetation density. The probability of vegetation loss at the same vegetation loss preset point gradually increases with increased drought severity. These results will facilitate the formulation of countermeasures to prevent and combat the effects of drought on vegetation and land management. Full article

Henan Province, a significant cultural heritage province in China, has abundant tangible cultural heritage resources distributed across the region. Watersheds are the fundamental geographical units that have consistently supported human production and subsistence activities from ancient times to the present. Analyzing the spatial distribution characteristics and influencing factors of tangible cultural heritage resources of the watersheds in Henan Province is of great importance for its macro-level preservation, value promotion, and sustainable development. This research focuses on the 421 major historical and cultural sites protected at the national level in Henan Province, utilizing GIS spatial analysis techniques such as kernel density estimation, nearest neighbor index, Thiessen polygons, spatial auto-correlation analysis, and geographically weighted regression to investigate the spatial distribution characteristics and influencing factors of tangible cultural heritage across different watersheds in the province. The results indicate the following: (1) The cultural heritage sites in Henan Province exhibit an overall clustered distribution. Within specific watersheds, such as the Jindihe River, Huaihe River, and Baihe River, the cultural heritage distribution is relatively sparse, displaying a random distribution pattern. (2) The cultural heritage distribution forms two high-density centers and one high-density distribution belt, exhibiting a tendency to align along lower-grade rivers. (3) The distribution of cultural heritage shows significant spatial auto-correlation, with high-value areas (hotspots) concentrated at the watershed intersections of the Yiluohe River, Weihe River, and Yinghe River. (4) Elevation, precipitation, GDP from the tertiary sector, museum density, and proximity to the nearest historical and cultural cities are the primary factors influencing the spatial differentiation of cultural heritage within each watershed. Moreover, there is significant spatial heterogeneity between different watersheds. Lastly, specific strategies for the sustainable preservation and utilization of cultural heritage in Henan Province are proposed, including differentiated preservation approaches, strengthening the preservation of water-related cultural heritage, promoting sustainable cultural tourism development, and establishing mechanisms for cross-regional cooperation. Full article

In the construction of water conveyance tunnels with the shield method, accidents have occurred from time to time, such as collapses and explosions, and it is of practical significance to explore the cause mechanism of the accident. However, previous research has not considered the effects of dependence between risks on the risk spread. In response, we propose a method based on the Natural Killing Model (the N-K Model) and complex network theory to analyze the cause of shield construction accidents in water conveyance tunnels. By deeply exploring the transmission mechanism and action intensity between system risks, this method can scientifically clarify the accident cause mechanism and provide support for engineering construction safety management. The method constructs a risk index system. Secondly, we introduce the N-K model to reveal the risk coupling mechanism. Then, based on complex network theory, we construct the incident causation model and revise the node’s centrality with the coupling value. Finally, the network topology parameters are calculated to quantitatively describe the causal characteristics of accidents, revealing the risk evolution process and critical causes. The research results indicate that the key causes of accidents are failure to construct according to regulations, inadequate emergency measures, poor ability of judgment and decision-making, and insufficient understanding of abnormal situations. The front end of critical links is subject to human or management risks and should be carefully controlled during construction. Full article

Recent anthropogenic activities have escalated human exploitation of riparian zones of river ecosystems, consequently diminishing aquatic biodiversity. This intensification of land use is also causing water quality degradation and changes in water environmental factors, evidenced by increased nutrient levels and adversely impacting the community structure and diversity of aquatic organisms. Notably, the Weihe River Basin, the largest tributary of the Yellow River, has demonstrated signs of significant anthropogenic pressure. Despite this, comprehensive investigations examining the effects of land-use intensity on aquatic organism diversity in this watershed remain limited. In this study, the environmental impacts and macroinvertebrate diversity under high-intensity and low-intensity land-use scenarios within the Weihe River Basin were investigated through field surveys conducted during the spring and autumn seasons. Our results demonstrated that areas under high-intensity land use exhibited elevated nutrient concentrations (e.g., total nitrogen) compared to those under low-intensity land use. These environmental changes significantly influenced the macroinvertebrate community structure, reducing functional and phylogenetic diversities in high-intensity land-use watersheds. Hydrological factors (water depth, river width, and discharge) have a significant impact on macroinvertebrate taxonomic diversity. Thus, understanding the effects of land-use intensity on aquatic biodiversity is essential for ecological assessments of impacted watersheds and developing management strategies for the sustainable use and planning of riparian lands in the Weihe River Basin. Full article

Ecological watersheds (eco-watersheds) are of great significance for boosting the construction of ecological civilization and realizing the ecological protection and high-quality development of watersheds. In order to establish a scientific eco-watershed evaluation index system, this paper refers to the river health evaluation index system, the water resources coupling evaluation index system, and the happy river evaluation index system, and reviews the development process of the ecological watershed evaluation index system. According to the eco-watershed theoretical system, combined with the relevant contents of policies and regulations, thousands of evaluation indicators that have been collected are screened using the theoretical analysis method and the frequency analysis method. Finally, a comprehensive evaluation index system of Weihe River eco-watersheds was constructed, including three first-level indicators: watershed water resources, socio-economic, and ecological. These were further subdivided into eight second-level indicators, namely water security, water resources, water economy, water management, water culture, water environment, water ecology, and water landscape. These second-level indicators were then further broken down into 60 third-level indicators. On the basis of determining the evaluation standards of Weihe River eco-watersheds, the evaluation weights were determined using the gray correlation method and the AHP-entropy comprehensive weight method (comprehensive weight), resulting in the establishment of an evaluation model and a coupling model for the eco-watersheds of the Weihe River. The results of the Weihe River eco-watershed evaluation model and the coupled coordination degree evaluation model show that, from 2019 to 2021, both the gray correlation analysis weights and comprehensive weight evaluation show a yearly increasing trend; the evaluation results are in the eligible status and below; and the evaluation grade is in the fourth-level eco-watersheds and below. Based on the evaluation results of each dimension, when comparing the gray correlation analysis weights with the evaluation of the comprehensive weights, the latter align more closely with the actual Weihe River Watershed. When comparing the evaluation results of the Henan Weihe River Watershed with those of the Handan Weihe River Watershed, the latter’s results, influenced by the scheduling of the Yuecheng Reservoir, are relatively better. Furthermore, in the evaluation of coupling coordination, the water resources subsystem is less coupled to other subsystems due to the 2021 flood. Therefore, in order to effectively improve the level of eco-watersheds, scientific and reasonable water resources scheduling programs should be developed. Full article