Search Results (17)

Many landslides triggered by earthquakes have caused a countless loss of life and property, therefore, it is very important to predict landslide hazards accurately. In this work, regional seismic landslide data were obtained via a field survey, remote sensing interpretation, and data collection, and a multilevel physical and mechanical parameter system for seismic landslide hazard assessment was established; this system included a landslide inventory, loose accumulation layers, and geological units, enabling higher accuracy in the data. The Newmark displacement model with a modified correlation coefficient was used to assess the regional seismic landslide hazard in four scenarios (a = 0.1, 0.2, 0.3, 0.4) to study the influence of the landslide hazard at different peak ground accelerations. Moreover, the information value model was used to modify the calculated results to improve their accuracy in the assessment. By assessing the potential seismic landslide hazard in Shimian County in the upper reaches of the Yangtze River, the regional landslide distribution and pattern at different peak ground accelerations were obtained. The results show that with decreasing parameter accuracy in the system, the importance of the landslide inventory increases. When the peak ground acceleration is a = 0.3, which can be defined as a high hazard grade, in which the landslide area demonstrates a large-scale sharp increase, a devastating hazard threshold is reached. As the peak ground acceleration increases, the factor controlling landslides transforms from the landslide inventory to the slope, which reflects the reasonableness of the parameters in the system. The input parameters were regarded as important factors for efficiently increasing the accuracy of the results of the Newmark displacement model in the discussion. Full article

Potential toxic elements (PTEs) pollution in the soil of abandoned open-pit mines can lead to great ecological risk to the areas around the mining districts. This study selected a typical abandoned open-pit iron mine along the Yangzi River in southeast China to investigate the spatial distribution, leaching characteristics, and ecological and health risk of the soil PTEs (As, Pb, Cd, Ni, Cr, Cu, and Zn). Leaching tests and sequential extraction were applied to study the migration of PTEs under the condition of rainfall. Different risk assessment methods were used to analyze the pollution and ecological risk of PTEs. The contents of As and Cu exceeded the background value of the Chinese soil guideline, with average contents of 50.71 ± 1.59 and 197.47 ± 16.09, respectively. The leaching test and sequential extraction indicated that sites 8 and 9 posed the greatest risk of PTE migration. According to the map of the Nemerow integrated pollution index (NIPI), the pollution level of the middle bare area of the study area was the highest, and Cu possessed the highest pollution index (PI) of 3.92. The average geo-accumulation index (I_geo) of As and Cu was between 1 and 2, reaching the pollution level of moderately contaminated. The average potential ecological risk coefficient (E_i) of As was the highest, and the contributions of As, Cu, and Cd to the potential ecological risk of the whole study area were 46.7%, 29.7%, and 14.3%, respectively. The range of the hazard index (HI) and the range of the As carcinogenic risk (CR_As) of all the sampling sites for children were 1.30–3.94 and 2.19 × 10⁻⁴–7.20 × 10⁻⁴, and As accounted for more than 85% of the total noncarcinogenic risk, indicating that the comprehensive pollution of PTEs in the study area posed great carcinogenic and noncarcinogenic risks to children. This study can be a proper reference for the subsequent recovery methods and environmental management of the whole mining area. Full article

The coordinated control of PM_2.5 and O₃ pollution has become a critical factor restricting the improvement of air quality in China. In this work, precursors and related influencing factors were utilized to establish PM_2.5 and O₃ estimation models in the North China Plain (NCP), the Yangzi River Delta (YRD), and the Pearl River Delta (PRD) using a multi-task-learning (MTL) model. The prediction accuracy of these three MTL models was high, with R² values ranging from 0.69 to 0.83. Subsequently, these MTL models were used to quantitatively reveal the relative importance of each factor to PM_2.5 and O₃ collaborative pollution simultaneously. Precursors and meteorological factors were the two most critical influencing factors for PM_2.5 and O₃ pollution in three regions, with their relative importance values larger than 29.99% and 15.89%, respectively. Furthermore, these models were used to reveal the response of PM_2.5 and O₃ to each precursor in each region. In the NCP and the YRD, the two most important precursors of PM_2.5 pollution are SO₂ and HCHO, while the two most critical factors for O₃ pollution are HCHO and NO₂. Therefore, SO₂ and VOC emissions reduction is the most important measure for PM_2.5 pollution, while VOC and NO₂ emission reduction is the most critical measure for O₃ pollution in these two regions. In terms of the PRD, SO₂ and NO₂ are the most important precursors of PM_2.5 pollution, while the most important precursors for O₃ pollution are HCHO and SO_X, respectively. Thus, NO₂, SO₂, and VOC emission reduction is the most critical measure for PM_2.5 pollution, while VOC and NO₂ emission reduction is the most critical measure for O₃ pollution in the PRD. Overall, this study provides clues and references for the control of PM_2.5 and O₃ collaborative pollution in the NCP, the YRD, and the PRD. Full article

Global warming may increase potential evapotranspiration (ETp), reducing the water resources in Yangzi River Delta. Therefore, it is important to investigate the trend of ETp there under the background of climate change. To this purpose, the systematic biases in temperature outputs of 24 global climate models (GCMs) under 3 shared socioeconomic pathways—representative concentration pathways (SSPs) emission scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5)—are first corrected by using 8 bias correction methods. Then, the trend of ETp in Yangtze River Delta is projected by using 4 ETp calculation formulas (Blaney–Criddle, Hargreaves–Samani, Makkink, and Priestley–Taylor). The uncertainty of the projections is estimated and decomposed by using multi-way analysis of variance frameworks. The influence of uncertainty on the projected change signal is quantified by using the signal-to-noise ratio. The results show that all emission scenarios indicate robust increments of ETp. Specifically, relative to 1971~2000, ETp will increase by 0.14~0.17 mm d⁻¹ (5.7~6.8%) during 2021~2050 and by 0.21~0.41 mm d⁻¹ (8.5~16.7%) during 2061~2090, respectively. During 2021~2050, the uncertainty of ETp projections is dominantly contributed by the main effects of GCM (63%) and the ETp calculation formula (24%). During 2061~2090, it is mainly contributed by the main effect of GCM (36%), followed by the main effects of the emission scenario (34%) and the ETp calculation formula (18%). The ETp projections are generally reliable and robust during the two projection periods. Full article

The anthropogenic disturbance caused by irrational urbanization impacts the ecological security of cities. The study of the relationship between urban spatial form (USF) and urban ecological resilience (UER) can offer guidance for sustainable urban development. We select the UER evaluation indexes and construct a DRSIR model based on the causal relationship among the natural, social, and economic dimensions of cities. We also carried out empirical research on the impact of USF on UER in the city cluster located in the Yangtze River midstream (YRM) through the geographical and temporal weighted regression (GTWR) model and geographical detector for four time cross-sections: 2005, 2010, 2015, and 2020. The following findings were obtained: (1) The computing results for UERIs of cities in the YRM noticeably and consistently increased during the study period, exhibiting a spatial distribution pattern with high values in the southeast, second-highest in the northwest, and low values in the center. (2) The regression coefficients of USFIs and UERIs displayed significant spatial and temporal variations in the YRM during the study period. (3) CA, AWMPFD, PD, and AI showed a positive correlation with UERIs, while PD exhibited a negative correlation with UERIs. (4) LPI and AI emerged as the primary drivers of spatial heterogeneity in UERIs, and the interaction between these two factors significantly enhanced their impact on UERIs compared to individual influencing factors. Exploring the correlation between UER and USF can be utilized to provide urban management recommendations that are suitable for the level of urban development, which will contribute to the achievement of sustainable development in the YRM. Full article

In this study, a new technique is proposed to retrieve temperature and relative humidity profiles under clear sky conditions in the Arctic region based on the artificial neural network (ANN) algorithm using Fengyun-3D (FY-3D) vertical atmospheric sounder suit (VASS: HIRAS, MWTS-II, and MWHS-II) observations. This technology combines infrared (IR) and microwave (MW) observations to improve retrieval accuracy in the middle and low troposphere by reducing the sensitivity of the neural networks (NNs) to cloud coverage. The approach was compared against other methods available in the literature on retrieving profiles only from FY-3D/HIRAS data. Furthermore, its retrieval performance was tested by comparing the NNs’ prediction accuracy versus the corresponding FY-3D/VASS and Aqua/AIRS L2 products. The results showed that: (1) NNs retrieval accuracy is higher during the warm season and over the ocean; (2) the retrieval accuracy of NNs has been significantly improved compared with satellite L2 products; (3) referring to radiosonde observations, the retrieval accuracy of NNs below 600 hPa is effectively improved by adding the information of the MW channel, especially on land where cloud clearing is more difficult. The root mean square error (RMSE) of temperature and relative humidity in the cold season were reduced by 0.3 K and 2%, respectively. The advanced NNs proposed herein offer a more stable retrieval performance compared with NNs built only by FY-3D/HIRAS data. The study results indicated the potential value in time and space domain of the NN algorithm in retrieving temperature and relative humidity profiles of the Arctic region from FY-3D/VASS observations under clear-sky conditions. All in all, this work enhances our knowledge towards improving operational use of FY-3D satellite data in the Arctic region. Full article

Most research on the water spirits of the Yangzi has focused on popular worship and paid little attention to the Confucian discourse and its major role in establishing imperial legitimacy. Yet it is a crucial aspect to understand traditional politics in China. The water spirits of the Yangzi River and its tributaries and lakes were venerated, offered imperial sacrifices, and incorporated into codes of state ritual in traditional China. The canonized sacrifices to the water spirits of the Yangzi River basin symbolized the religious–political legitimacy of the imperial regimes. When an imperial court offered sacrifice to the water spirits of the Yangzi River basin incorporated by previous dynasties, this action demonstrated that the current court directly connected to past regimes and inherited the authority of sacrifice passed down from the ancient and the orthodox tradition of Confucian ritual classics. Since the majority of dynasty capitals in traditional China were located in the north with fewer rivers, worshipping water spirits of the Yangzi River basin would imply recognition and blessing from southern divinities. The practice of granting noble titles and temple plaques to those water spirits would further demonstrate the imperial courts’ control over the divine power. By communicating with and managing the water spirits of the Yangzi River, the imperial courts would also symbolize their political and military administration over the south and they are united, rather than divided, regimes. Full article

The literary representation of China’s great rivers has repeatedly been transformed by changes in religious belief and ritual. In the Book of Songs, rivers figure primarily as political boundaries and figures of separation. Though they may already play a role in religious rites, their geographical identity is paramount. However, in the “Nine Songs” of the Elegies of Chu, they appear in a new guise as sites of divine encounter and shamanistic flight. Their treatment in later works may be regarded as a peculiar synthesis of these two traditions. Once the Four Waterways were designated as the object of state ritual in the Western Han, their divine status was widely accepted, along with explicitly political ramifications. For instance, the god of the Yellow River was honored as a participant in flood control and imperial governance writ large. Meanwhile, the tradition of the epideictic fu also celebrates the awesome scale of China’s waterways, reaching a culmination not long after the fall of the Han in Guo Pu’s (286–324) “Rhapsody on the Yangzi River”. However, it is noteworthy how often the fu tradition eschews material description of rivers in favor of celebrating their numinous powers and divine inhabitants. Because of this turn towards the divine in the medieval literary tradition, it is no accident that one of the most prominent subjects of fluvial verse in the Tang is not body of water at all but rather the Sky River, or Milky Way. Full article

Climate change and climate extremes and their impacts on agriculture, water resources, and ecosystems have become important issues globally. Agricultural sustainability and food security are facing unprecedented challenges due to the increasing occurrence of extreme climatic events, including, notably, extreme droughts in recent years in China. In this study, a threshold determination model of extreme agro-climatic droughts (EADs) was built based on the cumulative probability distribution functions (CDF) of an agricultural drought index—the consecutive days without available precipitation (CDWAP). The CDWAP was established by combining meteorological data with the characteristics of cropping patterns and the water requirement in different growing periods of crops. The CDF of CDWAP was obtained based on the relationship of CDWAP and its occurrence frequency. Based on the model, the spatial pattern of the thresholds of EADs and the threshold exceedance time series of EADs in 500 meteorological stations were obtained, and then changes in the frequencies and intensities of EADs in China and their impacts on grain yields in rain-fed regions during the past 50 years were analyzed. The results follow: (1) The threshold value of EADs in China gradually increased from southeast to northwest. The stations of the highest value were located in the Northwest China, with the CDWAP more than 60 days, while the lowest value was in the middle reaches of the Yangzi River, with the CDWAP less than 16 days. (2) The frequencies and intensities of the EADs increased mostly in the east areas of the Hu Huanyong line, which was also the main agricultural production region in China. The North China (NC) and Southwest China (SW) regions showed the highest increasing rates of the EADs; their frequencies and intensities were 11.3% and 2.2%, respectively, for the NC region, and 9.3% and 2.7%, respectively, for the SW region. (3) Case studies in the NC, SW, and SE regions indicated that there was a negative correlation between grain yields and EAD frequency and intensity; i.e., the low grain yields often occurred in the year with relatively higher frequency or/and stronger intensity of EADs. The correlation coefficients of grain yield and EAD were generally greater than that of merely extreme climatic droughts; therefore, the study of EAD is necessary when researching the impacts of extreme drought events on grain yield. Full article

Fatigue cracks often occur in the deck asphalt pavement of steel bridges at the top of the longitudinal stiffening rib. To prevent this issue, the traditional design strategy of the steel bridge deck asphalt pavement structure was optimized, and a new approach is presented. This optimization technique exploits the strength simulation of the steel—epoxy asphalt pavement structure, and the stress concentration location is subsequently determined. A solid model of stress concentration including sensitive areas is then established. We examined the stress maximum point of the asphalt pavement layer at the top of the longitudinal stiffeners and the stress variation of the asphalt pavement layer at the top of the longitudinal stiffeners. To reduce the stress of the top pavement layer of the longitudinal stiffeners, an optimization method that combines orthogonal experimental design, neural network (BP), and genetic algorithm (GA) is presented. A design strategy for the steel—epoxy asphalt pavement structure and GA—BP optimization method was utilized to optimize the structure of the steel—epoxy asphalt pavement for Sutong Yangzi River Bridge. We confirmed that the presented approach improved fatigue reliability and established the efficacy of the design strategy and optimization method. Full article

Data and literature related to water quality as well as nutrient loads were used to evaluate the Changjiang River (also Yangtze or Yangzi) Basin with respect to its hydrological regime, sediment transport, and eutrophication status. Waterbodies exhibited different eutrophic degrees following the ranking order of river < reservoir < lake. Most of the eutrophic lakes and reservoirs distributed in the upstream Sichuan Basin and Jianghan Plain are located in the middle main stream reaches. During the past decade, the water surface area proportion of moderately eutrophic lakes to total evaluated lakes continually increased from 31.3% in 2009 to 42.7% in 2018, and the trophic level of reservoirs rapidly developed from mesotrophic to slightly eutrophic. Construction and operation of numerous gates and dams changed the natural transportation rhythm of runoff, suspended solids (SS), and nutrients, and reduced flow velocity, resulting in decreased discharge runoff, slow water exchange, and decreased connectivity between rivers and lakes as well as accumulated nutrient and SS, which are the main driving forces of eutrophication. To mitigate eutrophication, jointly controlling and monitoring nutrient concentrations and flux at key sections, strengthening water quality management for irrigation backwater and aquaculture wastewater, and balancing transportation among runoff, SS, and nutrients is recommended. Full article

Increases in climate extremes and their impacts have attracted global attention recently. In this study, the change-point years of precipitation extremes (PEs) and drought extremes (DEs) were investigated by Moving t-Test at 500 stations across the six regions in China. The detailed temporal change processes of them were demonstrated by the cumulative deviation method based on the data from nine typical stations. The results showed that: 1) DEs were more significantly and widely increased than PEs, the stations with increasing trends of PEs and DEs accounted for greater than 52.6% and 61.6% of the total, respectively; 2) increasing trends of DEs were mainly distributed in the east of Hu Huanyong Line. In this area, the increasing change-point years of DEs often occurred in the early 1980s in the south of the Yangzi River, while occurred in the 1990s in the north of the Yangzi River; 3) increasing trends of PEs were mainly distributed in Qing-Tibet Platen, Northwest China, and the southeastern area of Hu Huanyong Line. In these areas, the increasing change-point years of PEs often occurred around 1990 in the southeast of Hu Huanyong Line, while often occurred in the early 1980s in Qing-Tibet Platen. The results indicated that the area in the southeast of Hu Huanyong Line was under the threats of both PEs and DEs, this may produce severe impacts on agriculture, environment, water resources management, human society, etc. Full article

Whether the supplies of health services and related facilities meet the demand is a critical issue when developing healthy cities. The importance of health services and related facilities in public health promotion has been adequately proved. However, since the community population and resource data are usually available at the scale of an administrative region; it is very difficult to perform further fine-scaled spatial distribution equilibrium evaluation studies. Such kinds of activities are highly expected for precise urban planning and management. Yichang is located in Hubei province, the central part of China, along the Yangzi River. It is leading both of China’s smart cities demonstration project and China’s healthy cities pilot project. Yichang has defined 1271 community grids for urban management and service, where each grid consists of 200 households generally with its population distribution data routinely updated. The research set the 15-min walking distances of the residents as impedance factors, and the numbers and the types of health service resources as attractiveness factors for accessibility evaluation. The resource ratio, richness and per capita number of various health service resources that can be reached within 15 min from the community grid building is used as spatial distribution equilibrium evaluation indicators. The entropy weight method is used to assign the indicator weight value. The obtained fine-scale evaluation results were analyzed. In this way, a community grid-scale spatial distribution equilibrium evaluation of health service resources in Yichang was performed. The proposed research could be of value for rapid and precise evaluation of spatial distribution equilibrium evaluation of a variety of healthy city resources, to support healthy city planning and management. Full article

In order to monitor and manage vessels in channels effectively, identification and tracking are very necessary. This work developed a maritime unmanned aerial vehicle (Mar-UAV) system equipped with a high-resolution camera and an Automatic Identification System (AIS). A multi-feature and multi-level matching algorithm using the spatiotemporal characteristics of aerial images and AIS information was proposed to detect and identify field vessels. Specifically, multi-feature information, including position, scale, heading, speed, etc., are used to match between real-time image and AIS message. Additionally, the matching algorithm is divided into two levels, point matching and trajectory matching, for the accurate identification of surface vessels. Through such a matching algorithm, the Mar-UAV system is able to automatically identify the vessel’s vision, which improves the autonomy of the UAV in maritime tasks. The multi-feature and multi-level matching algorithm has been employed for the developed Mar-UAV system, and some field experiments have been implemented in the Yangzi River. The results indicated that the proposed matching algorithm and the Mar-UAV system are very significant for achieving autonomous maritime supervision. Full article

Nighttime Light (NTL) has been widely used as a proxy of many socio-environmental issues. However, the limited range of sensor radiance of NTL prevents its further application and estimation accuracy. To improve the performance, we developed an improved Vegetation Adjusted Nighttime light Urban Index (VANUI) through fusing multi-year NTL with population density, the Normalized Difference Vegetation Index and water body data and applied it to fine-scaled carbon emission analysis in China. The results proved that our proposed index could reflect more spatial variation of human activities. It is also prominent in reducing the carbon modeling error at the inter-city level and distinguishing the emission heterogeneity at the intra-city level. Between 1995 and 2013, CO₂ emissions increased significantly in China, but were distributed unevenly in space with high density emissions mainly located in metropolitan areas and provincial capitals. In addition to Beijing-Tianjin-Hebei, the Yangzi River Delta and the Pearl River Delta, the Shandong Peninsula has become a new emission hotspot that needs special attention in carbon mitigation. The improved VANUI and its application to the carbon emission issue not only broadened our understanding of the spatiotemporal dynamics of fine-scaled CO₂ emission, but also provided implications for low-carbon and sustainable development plans. Full article