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The Chengdu Plain serves as the central hub for economic development in Sichuan Province. The study of its surface deformation plays a pivotal role in disaster prevention and ensuring the safety of lives and property. Based on SBAS-Interferometric Synthetic Aperture Radar technology, this paper derived the land surface deformation in the Chengdu Plain from January 2020 to October 2022, and analyzed it in relation to urban development and other natural environmental factors. Results are as follows: (1) The overall surface deformation in the study area remains stable, with a noticeable trend of westward uplift and eastward decline. Significant uplift is identified in Dujiangyan and Pengzhou, located near the Longmen Mountain, with a maximum uplift rate of +61 mm/year. Conversely, subsidence is evident from Qingbaijiang District in Chengdu to Deyang, with subsidence rates reaching a maximum of −87.8 mm/year. In the areas of Dayi and Qionglai, subsidence is relatively minor. The surface subsidence phenomenon in the study area is primarily associated with urban development. (2) The mean grey correlation coefficient between the time-series cumulative surface deformation and precipitation is 0.71, which suggests a strong relationship between the surface deformation and precipitation in the Chengdu Plain. However, a time delay is observed between the changes in surface deformation and precipitation. (3) The Longmen Mountain tectonic belt extrudes and lifts the premountain plain, playing a crucial role in shaping its topography. Additionally, the concealed fracture zone of Xinjin-Chengdu-Deyang may have contributed to surface subsidence. (4) After eliminating the effect of human factors, the cultivated land and grass land cover types exhibit a subsided state, whilst the artificial surface deformation is relatively stable, and the forest land exhibits an uplifted state. Surface deformation on different land cover types is correlated with water permeability, but it is also influenced by other factors. [ABSTRACT FROM AUTHOR]

The improvement of protected areas (PAs) is a global challenge for society. In 2017, China implemented the ambitious "Ecological Conservation Redline" (ECR) program, with the aim of increasing its PA estate and improving human welfare. Since its implementation, the ECR has attracted much attention from both researchers and managers. However, the understanding of the ECR by some researchers is still unclear, resulting in debates about its practicality and effectiveness. We therefore provide a clear description of the ECR in this paper. The ECR was proposed as a conservation theory in China in 2011 and was transformed into nationwide practice in 2017. Compared with existing PAs, the ECR expanded the conservation network by considering hotspots of ecological function and fragility beyond biodiversity, which was highlighted by the example of Sichuan Province, China. To balance the demands of conservation and development, a list of "positive" human activities is presented following negotiations between government and stakeholders. In addition, a remote sensing platform and an ecological compensation system have been applied to provide technological and economic support to the ECR. Finally, we make recommendations for improving the redline identification method, evaluating the effects of its implementation, broadening the funding sources for ecological compensation, and strengthening legal safeguarding. The advancement of the ECR provides a new model for environmental planning leading to a sustainable future. • China's Ecological Conservation Redline program aims to improve the protected area network. • The redline concept considers hotspots of ecological function and fragility beyond biodiversity. • This paper clarifies the program and its core principles. • Recommendations are made to enhance the redline identification method and its evaluation. • Ecological compensation funding and strengthening legal safeguarding are also necessary. [ABSTRACT FROM AUTHOR]

Under the influence of COVID-19, the global economic and social development is facing great challenges. With the increase of government financial pressure and the decrease of debt paying ability, the problem of debt risk of local governments in China is attracting wide attention. In order to measure the level of China's local government debt risk under the influence of COVID-19, this paper takes China's Sichuan Province as an example, collects the core indicators data of measuring local government debt risk in 2017-2020 years, and uses AHP-TOPSIS method to make a comprehensive analysis of the local government debt risk situation in different periods before and after COVID-19. It is found that the local government debt risk in Sichuan Province is generally controllable. However, influenced by COVID-19, in 2020, the overall level of local government debt risk in Sichuan province expanded by 22.1% compared with 2019, this is mainly due to the further expansion of debt scale and slower economic growth. This paper suggests that the Chinese government should speed up the construction of comprehensive early warning and supervision system of local government debt risk, and prevent and resolve the debt risk of local government in advance. [ABSTRACT FROM AUTHOR]

Dynamic monitoring and prediction of ecosystem service value (ESV) under land utilization change is of great significance to maintaining regional ecological security. In order to enrich the study of ESV changes in plateau region by using the improved equivalent factor method of unit area value, the western Sichuan Plateau was taken as the research object. In this paper, given the land use data of the western Sichuan Plateau in 2000, 2010 and 2020, efforts have been made to construct the suitability image collection of the study area and to amend the CA-Markov model as to predict the land use pattern in 2030. In addition, the improved ESV evaluation model was constructed to study the spatial and temporal dynamic variation features of ESV. The results showed that: Woodland and grassland are the main types of land utilization in the study area. There are frequent interchanges between various land utilization types. The overall reduction of ESV, decrease of 3.4917 × 109 yuan/a, mainly due to the conversion of woodland to other land types. The high-value areas of ESV in the study area are closely tied to rivers. Two areas with high ESV value were formed in the study area. The findings of the study enriched the research system of land use and ecosystem service value in the plateau region, provided basic data for the construction of regional ecological security pattern, and enhanced regional sustainable development. [ABSTRACT FROM AUTHOR]

Green production in agriculture is a critical project for achieving the United Nations 2030 Sustainable Development Goals (SDGs). Using pesticide safety as an entry point, this paper explores safe agricultural production and proposes initiatives from the origin source, which are essential to address multiple SDGs, including food security, health, and the environment. Using research data encompassing 612 peasant households in Sichuan province, China, this paper examines the mechanisms of social learning on farmers' safe pesticide use behavior employing exploratory factor analysis, Oprobit model, and Bootstrap method. The results show that social learning has significantly positive effects on farmers' safe pesticide use behavior, with each additional point of social learning contributing to a 3.411% increase in the chance of taking 6 safe pesticide use behavior. The effect sizes of different social learning styles were in the order of role demonstration, neighborhood communication, and participation in training, but proactive learning by consulting did not work significantly. Furthermore, perceived value has a positive mediation effect in social learning to impact farmers' safe pesticide use behavior, accounting for 34.53% of mediation effect. Finally, the market conditions can positively moderate the mediation effect of perceived value on farmers' safe pesticide use behavior, i.e., the better the accessibility to green production materials, marking and pricing stabilization, the stronger the effect of perceived value on safe pesticide use behavior. However, information access doesn't work that way. Therefore, in the future, the government must encourage farmers to participate in social learning and improve their perceived value, as well as play a macro-control role and fulfill market conditions. [ABSTRACT FROM AUTHOR]

This paper proposes an intelligent slope stability prediction method based on the improved pelican optimization algorithm (IPOA) and the optimization random forest (RF) algorithm to reduce disasters and accidents caused by slope instability. First, exploratory data analysis (EDA) is performed using correlation diagrams, heat maps under different states, box plots, histograms, and quantile–quantile (Q-Q) diagrams of variables, followed by establishing a high-quality data set for slope engineering cases and an index system for slope stability prediction. Second, 10 benchmark functions reveal that the IPOA algorithm outperforms other algorithms. Accordingly, this paper develops a slope stability prediction model based on the IPOARF algorithm. Afterward, a set of intelligent slope stability prediction systems is created using MATLAB tools and applied to Lala Copper Mine in Sichuan Province. Finally, this paper compares the accuracy of various models and subjects the proposed model to additional testing. The results reveal that the prediction model based on improved IPOA and RF algorithms is reliable and effective, with an accuracy of up to 90.4%, which can serve as a solid technical basis for slope instability disaster prediction in geotechnical engineering. [ABSTRACT FROM AUTHOR]

The urgent need to address climate change, driven by the increasing concentrations of greenhouse gases, has made it imperative for the world to focus on enhancing carbon emission mitigation and carbon utilization. Consequently, carbon-negative technologies have garnered significant attention, such as Carbon Capture, Utilization, and Storage (CCUS). In order to achieve the circular utilization of carbon and improve the economic viability of conventional carbon-negative technologies, this paper proposes the innovative concept of Carbon Capture, Circular Utilization, and Sequestration (CCCUS). This multifunctional carbon-negative technology couples underground biomethanation of carbon dioxide and hydrogen-rich industrial by-product gases with geothermal energy production. CCCUS also offers several additional functions, such as renewable natural gas storage, natural gas displacement, and carbon dioxide geological sequestration. Furthermore, a preliminary assessment of the techno-economic feasibility of CCCUS is undertaken. A numerical case study, conducted using the XGS gas storage in the Sichuan Basin, China, unveiled that over a 425-day period, the conversion ratio of carbon dioxide to methane in the working gas can achieve 98.9%. Moreover, the net present value (NPV) of CCCUS over a 30-year period is estimated to be approximately 4.67 × 108 CNY under the base scenario. These findings, along with field monitoring and laboratory experiments, preliminarily present evidence supporting the potential techno-economic feasibility of CCCUS. This paper offers a fresh perspective on the development of the circular carbon economy. [ABSTRACT FROM AUTHOR]

The earthquake and its secondary geological disasters have some long-term effects on vegetation recovery, and the spatiotemporal differentiation of vegetation coverage in earthquake-stricken areas are often not valued by researchers. Beichuan County in Sichuan Province is the worst-hit area during Wenchuan earthquake, tracking the vegetation coverage in this disaster area can provide feedback for post-earthquake ecological restoration. Based on remote sensing (RS) and Geographic information system (GIS), this paper relies on dimidiate pixel model (DPM) and vegetation coverage transfer matrix to explore the vegetation coverage of the earthquake worst-hit area. The results show that the overall level of vegetation coverage in Beichuan county is high, and earthquakes are dominant in the areas with high vegetation coverage. Besides, earthquake can do most severe damages to the areas with high vegetation coverage, followed by medium damage impacting to the areas with medium vegetation coverage, but the damage of other areas are relatively small. From 2007 to 2020, the average vegetation coverage in Beichuan County decreased from 0.835 in 2007 to 0.755 in 2008, then gradually recovered to 0.826 in 2020, experiencing a sharp decline and then a steady increase. The recovery of vegetation coverage is improved over time, but the spatiotemporal differences of the recovery process are obvious. Elevation has the largest driving force on vegetation coverage (q = 0.569, p less than 0.001), followed by temperature and rainfall; the interaction between factors has a significant increasement in the spatial differentiation of vegetation coverage, indicating that vegetation coverage is a combination result of multiple factors. The research findings can help construct the scientific management of the eco-environment in the disaster area, it can also help builda medium to long-term ecological restoration plan according to the variation in vegetation coverage. [ABSTRACT FROM AUTHOR]

The structures of the Southwest Vortex (SWV) differ depending on the different environmental conditions, ultimately resulting in various types of disasters. Based on SWV Year Book during 20122017, this paper mainly makes statistical analysis on the characteristics of summer SWV and winter SWV. The radius and vertical depth between summer and winter SWVs are compared. Using composite method, PV tendency equation and angular momentum, the differences of both types of SWV scales are analyzed to reveal environmental conditions and the mechanism of different scales. The result shows that:(1) approximately 90% of winter SWVs are characterized by shallow pattern, but the percentage of summer SWVs sharing the similar pattern drops below 50%. Additionally, the average radius of SWVs in both seasons exhibits distinct variations with summer SWVs and winter SWVs reaching 100 km and 130 km, respectively. (2) Higher levels of environment angular momentum are exhibited in summer compared to winter, resulting in lager radius of winter SWV than summer SWV. (3) The PV tendency equation suggests that the diabatic heating effect is benefited to transport PV to higher level and strong convergence resulting in higher vertical extension height and radius contraction. (4) Winter SWV exhibits a wide range of inertial stability, which negatively affects the transport of angular momentum to the vortex core, consequently causing a maximum tangential wind and transport of angular momentum to appear outside the core. • Compared to the winter Southwest Vortex (SWV), the summer SWV is deeper on vertical scale but narrower on horizontal scale. • Winter conditions, such as lack of water vapor and more angular momentum, are more conducive to generating larger but not deeper SWV. • A mechanism contributing to the differences in summer and winter SWV scales is proposed. [ABSTRACT FROM AUTHOR]

The construction of the deep-buried tunnels of the Sichuan-Tibet railway is facing severe rockburst disasters. Pressure relief boreholes and rock bolt support are effective methods for mitigating rockburst in hard rock. However, the mechanisms and differences in control effectiveness of these methods for different types of rockburst have yet to be revealed. This paper presents the results of two true triaxial unloading rockburst tests: Static-driven rockburst (static tests) due to excavation disturbance and dynamic-triggered rockburst (dynamic tests) due to adjacent tunnel excavation. The rockburst samples include intact granite, granite with a borehole (hole-granite), and granite with a negative Poisson's ratio bolt (bolt-granite). The mitigation mechanisms of the borehole and bolt were investigated in terms of rockburst intensity, failure patterns, and acoustic emission precursors. The results show that borehole and bolt inhibit the formation of a shear fracture plane during rockburst, with the bolt's inhibition effect being more pronounced. For static tests, borehole and bolt significantly reduce rockburst intensity, with the reduction being more significant for bolt-granite. The bolt mainly inhibits the propagation and penetration of shear microcracks. In contrast, the borehole promotes the propagation of shear microcracks. However, for dynamic tests, the rockburst intensity of bolt-granite is equivalent to that of intact granite, while the borehole enhances the rockburst intensity. The bolt inhibits the final buckling crack penetration in dynamic tests, while the borehole promotes slabbing. For static and dynamic tests, the borehole has little influence on precursor indicators, while the bolt increases the difficulty of precursor capture. Generally, the pressure relief borehole is more effective in controlling static tests, while bolt-reinforced support has advantages in dynamic test control. • Rockburst mitigation mechanisms using stress relief borehole and rock bolt support were revealed. • Static and dynamic rockburst tests were conducted on intact granite, hole-granite, and bolt-granite. • Pressure relief borehole is more effective in controlling static tests. • Boreholes and NPR bolts inhibit the formation of shear fracture during rockburst. • The borehole does not influence the optimal AE precursor, but the bolt increases the difficulty of capturing it. [ABSTRACT FROM AUTHOR]

The academia has paid much attention to the ecological protection and poverty alleviation functions of carbon sink afforestation project (CSAP), an important means to realize forestry carbon sink. However, whether CSAP can promote county industrial structural upgrading (ISU) and propel high-quality economic development remains unanswered. Based on the panel data of counties in Sichuan Province, China in 2000–2016, this paper estimates the impacts of CSAP on ISU through difference-in-differences with variation in treatment timing (VTT-DID) and synthetic control method. The results show that: CSAP can improve the advanced level of county industrial structure. This finding remains valid after a series of robustness tests. Government guidance dominates the impacts of CSAP on ISU, while market regulation plays a limited role in the impact mechanism due to the presence of elite capture. Government guidance and market regulation have a positive synergistic effect. The ISU impacts of CSAP are affected by resource endowment, level of economic development, and culture difference of ethnic monitories at the county level. Mechanism analysis shows that CSAP mainly acts on county ISU by increasing capital accumulation. The research results provide a reference path for China to transform its concept of economic development, and the key evidence for the fact that CSAP is an important way to realize high-quality economic development and environment protection at the county level. [ABSTRACT FROM AUTHOR]

• The paper constructed a RECC calculation method based on the EWM-CPM. • The spatiotemporal characteristics of RECC in resource-based cities. • The relationship between RECC and NEES is deconstructed by the path analysis method. The development of resource-based cities faces with stagnation due to the exhaustion of resources. Scientific and rational characterization of the temporal and spatial characteristics of resource environmental carrying capacity (RECC) is conducive to the sustainable development of these cities. In the present study, 8 resource-based cities in Sichuan Province were used as the research objects. A RECC research framework was constructed based on natural resources, environmental resources, economic resources and social resources dimensions (NEES), and a RECC assessment system was then extracted. This paper constructed a RECC calculation method based on the EWM-CPM (EWM: entropy weight method, CPM: catastrophe progression method). Mean and standard deviation were used for statistical analysis of RECC. The temporal trends of the NEES and RECC of resource-based cities in Sichuan Province were analyzed from the perspective of time, and the dynamic characteristics were analyzed combined with the dynamic evaluation measure model. The spatial pattern of RECC in the resource-based cities in Sichuan Province was analyzed from a spatial perspective. The relationship between NEES and RECC was evaluated through a path analysis method. The research results were as follows: (1) In terms of time, the average value of RECC in the resource-based cities in Sichuan Province was 0.628, and the standard deviation was 0.200, indicating that the stability of RECC in the entire region was poor. Natural resources are the main subsystem of RECC impacts in NEES. From the calculation results of the dynamic evaluation measure model, the level of RECC in PZH (Panzhihua) was stable, and the level of RECC in GA (Guang'an) increased with time, whereas the level of RECC in NC (Nanchong) was poor. (2) In terms of space, the eight resource-based cities showed uneven development in regard to RECC from 2010 to 2019, and the urban advantageous industries were related to the types of resources in the NEES. (3) The path analysis method results indicated that the directional impact of natural resources on RECC was the highest (0.658), followed by the effect of social resources, environmental resources and economic resources. The findings of the present study provide a basis for the establishment of methods for the sustainable development of urban areas, effective information extraction and the integrated assessment of factors that affect the development of resource-based cities. [ABSTRACT FROM AUTHOR]

Hydropower resources have been developed to the cold regions in the west of China recently, wherein the dam will be subjected to high frequency of repeated freeze-thaw action during the construction process in winter, and thus will cause safety and stability problems of these projects. According to the actual construction situations of Lianghekou hydropower station located in Sichuan Province, one-side freezing and two-side thawing tests of unsaturated core-wall soil samples in a closed system are carried out, and the evolution of temperature, water and displacement as well as their interaction are tested and analyzed. The results show that with the increasing of freeze-thaw cycles, water migration results in a decrease of water content in the unfrozen zone and an increase in the frozen zone, and the water concentration area is formed in the soil column. Simultaneously, a deeper freezing depth accompanied with a shorter thawing duration after 10 freeze-thaw cycles is observed through the temperature field results, whereas a steady fluctuation of the deformation field is showed after the 7th freeze-thaw cycle. Moreover, based on the test results and exiting researches, a thermo-hydro-mechanical coupling model for unsaturated soils subjected to cyclic freeze-thaw action is proposed, in which both the permeability and compressibility are inextricably related to the void ratio, and vary in different calculated areas. Additionally, the effects of number of cycles on initial conditions and model parameters are also considered. Comparisons with the experimental data demonstrate the validity and adaptability of the proposed model in describing the freeze-thaw process of unsaturated soil. Through the combination of experiments and numerical simulation, the freeze-thaw process can be more clearly understood, and related engineering problems can be predicted with the help of the mathematical model in this paper. • One-side freezing and two-side thawing tests of unsaturated soil are carried out. • A thermo-hydro-mechanical coupling model in freeze-thaw process is proposed. • The thermo-hydro-mechanical coupling mechanism is revealed by simulations. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Pianyanzi area in western Sichuan hosts a rare sellaite-bearing orogenic gold deposit. • Gold is mostly present as visible native gold formed in two stages. • Gold precipitation was forced by interaction between auriferous fluids and wall rocks. • Metasomatized mantle lithosphere served a potential source of ore fluids. The Pianyanzi gold deposit is situated at the western margin of the Yangtze Craton, and represents a rare sellaite-bearing orogenic gold deposit. This deposit belongs to the Dauduhe gold belt of southwestern China and remains poorly documented. In this paper we present first petrographic and in-situ geochemistrical and sulfur isotope data from pyrite as well as results of multielement mapping. The deposit is dominated by native gold (average gold fineness = 980.8) filling fractures in minerals (e.g., pyrite, quartz, sellaite and hematite) or also emplaced along the contact interface between mineral grains. Pyrite is the most abundant sulfide mineral of this deposit. We identified five generations of pyrite: Py1, Py2a, Py2b, Py3, and Py4. Gold occurs in sellaite- and hematite-bearing mineral assemblages formed simultaneous with the formation of Py2a&b and Py4, respectively. Py1 formed in the Au-poor ore stage, while Py3 formed during the late galena-dominated sulfide stage. All generations of pyrite exhibit low concentrations of gold with an average value of less than 2 ppm. Py2a&b possess distinctive textures and chemical zonation, with trace elements displaying greater variations compared to Py1, Py3 and Py4. The δ34S values vary from −0.52 ‰ to 7.08 ‰, which is consistent with those of orogenic deposits of the Daduhe gold belt. The deep metasomatized mantle lithosphere acted as a potential source of ore fluids. We conclude that the co-precipitation of native gold and sellaite was triggered by the interaction between auriferous fluids and dolomite. [ABSTRACT FROM AUTHOR]

Yibin area is located in the southwestern margin of Sichuan Basin of upper Yangtze River basin, close to the southeastern boundary of the Qinghai-Tibetan Plateau. The paleoclimatic characteristics recorded by Quaternary river sediments in this area can display the impact of uplift of the Qinghai-Tibetan Plateau on paleoclimate change of Sichuan Basin. In this paper, the macro-characteristics, clay minerals and the diagnosis geochemical elements characteristics of the sediments of terraces and floodplain were used as climatic proxies to explore the evolutionary process of the Quaternary paleoclimatic change in the study area. Key findings can be shown as follows: 1) warm and humid paleoclimate occurred during the Middle Pleistocene and the early Late Pleistocene (730–90 ka), shown by the high values of Al 2 O 3 , Fe 2 O 3 , Rb/Sr, chemical index of alteration (CIA, 82–97), illite chemical index (ICI, >0.5), kaolinite and the low values of Na 2 O, K 2 O, MgO, K 2 O/Al 2 O 3 , (CaO + Na 2 O)/Al 2 O 3 , illite, smectite, chlorite from the brown or brownish-red sediments of the terraces T5 to T3. 2) The reversal values of these geochemical and clay mineral proxies (e.g., values of CIA between 50 and 64) derived from grey and greyish-yellow sediments in terrace T2 and floodplain denote the dry and cold paleoclimate, emerging in the middle-late Late Pleistocene (50 ka), corresponding to the Baiyu glacial period of the Qinghai-Tibetan Plateau. Comparing the paleoclimatic evolutionary characteristics in Yibin area with those of the Three Gorges area of northeastern margin of Sichuan Basin from previous researches, this paper considers that during the Gonghe tectonic movement (0.15 Ma), the uplift of the Qinghai-Tibetan Plateau and its southeastern boundary intensified the Plateau winter monsoon and caused the southwesterly withdrawal of the Indian monsoon from Sichuan Basin. Consequently, the warm and humid paleoclimate at the northeastern and southwestern margins of the Basin had successively become dry and cold in the early and middle-late periods of the Late Pleistocene. • Paleoclimate information can be well preserved in terrace sediments in Yibin area. • The paleoclimate in Yibin area had changed from warm and wet to cold and dry since 50 ka. • Quaternary paleoclimate changed to dry and cold from northeast to southwest in the Sichuan Basin. • Tibetan Plateau's Gonghe tectonic movement enhanced the Plateau monsoon and blocked the Indian summer monsoon. • Influence of Indian summer monsoon weakened in the Sichuan Basin along the SW direction after 110 ka. [ABSTRACT FROM AUTHOR]

[Display omitted] • Apply a more realistic approach to independent black/odor evaluation. • Hilsenhoff biotic index is most suitable as an indicator of the degree of black odor. • The number of the genus Chironomidae is indicative of the black and odor. Macroinvertebrate community structure parameters can reflect the water quality and water ecosystem health status of rivers. In this paper, using the results of macroinvertebrates in 16 urban rivers in Sichuan Province from November 2020 to March 2021, we independently evaluated the level of black odor in urban rivers based on the mathematical model. On this basis, we examined the community structure, fouling tolerance, diversity, and feeding functional groups of macrobenthos in rivers with different degrees of black odor. During the study, a total of 39 species of macroinvertebrates were collected and identified to 3 phyla, 7 classes, 16 orders, 26 families and 30 genera. Urban rivers changed from non-black and non-odorous to black and odorous: (1) the dominant species, Chironomus flaviplumus , Physa fontinalis and Barbronia weberi , changed to Chironomus flaviplumus , a fouling-tolerant species with wide adaptability; (2) According to the tolerance values (TVs), the pollution resistance categories gradually increased as the level of black odor increased, which indicated the level of black odor in water bodies; (3) The calculation of the Hilsenhoff biotic indices (HBI) indicated that 83.3% of the sampled sites were moderately to heavily polluted. In general, the severity of water quality pollution in the black and odorous type of river was significantly higher than that in the non-black and odorous type of river, and with the deepening of the degree of blackness and odor the quality of the water deteriorated; (4) The community structure had an unstable community structure and a low diversity index of macroinvertebrate species; (5) The taxa of feeding functional groups shifted from the presence of all five types of feeding functional groups to the dominance of fouling-resistant species represented by scrapers. The results summarize the characteristics and change patterns of various indicators under different black-odorous degrees, indicating that the HBI can be used as an alternative indicator for the evaluation of black odorous water, and the number of species of Chironomidae can indicate the degree of black odor in water bodies. [ABSTRACT FROM AUTHOR]

To secure effective and sustainable climate change policies, it is of the utmost importance to create synergies between socioeconomic and environmental development goals. Payments for Ecosystem Services (PES) programs are being promoted as a suitable mechanism furthering, among others, carbon offsetting and poverty reduction in ecologically fragile areas of developing countries. Rural households are compensated for the loss of property and business income through income transfers and potential job opportunities connected to environmental programs. While the potential pro-poor effects of such policies are well recognized, the impact of PES on extremely poor households has not been systematically reviewed. Drawing on a pooled cross-sectional dataset of 5225 households in the Province of Sichuan, this paper analyzes the income and distributional effects among poor households in rural China participating in a forest carbon sink (FCS) program. To be able to make causal inferences, we employ an Instrumental Variable (IV) approach to control for potential endogeneity and self-selection. Our results indicate a strong need to adjust the PES program: While moderately poor rural households benefit from program participation, extremely poor rural households, in fact, suffer net losses. The main reason is that income reduction resulting from limited access to forest resources is compensated mainly via wage income from participating in forest tending work. Extremely poor households with low labor ability cannot make use of these job opportunities, and thus they'll not only fail to benefit but even incur losses from a PES program. While PES programs can be a viable tool for poverty reduction in underdeveloped regions due to their overall pro-poorness, they need to be accompanied by additional benefits for extremely poor rural households to avoid net losses among marginalized population groups especially. [ABSTRACT FROM AUTHOR]

Trombe wall is an effective method for passively absorbing solar energy and providing heat to buildings. This paper conducts a comparative experiment between Trombe wall buildings and glass curtain wall buildings during the winter season in Songpan County, western Sichuan. The climate characteristics of the western Sichuan plateau are analyzed, and the potential applications of these two building types in the region are investigated. To further understand the heat transfer mechanism of Trombe wall buildings, numerical simulations are carried out to analyze the indoor thermal environment of buildings with varying air channel thicknesses. The results show that Trombe wall buildings are more effective at delaying heat loss compared to glass curtain wall buildings, due to the thermal storage of the Trombe wall providing heat at night. This makes Trombe wall buildings well-suited for regions with strong solar radiation and large temperature differences between day and night, such as the alpine region. However, excessively small air channel thickness can lead to excessive air flow speed during the day, causing more heat loss and weaker insulation at night. Conversely, excessively large air channel thickness reduces air flow temperature difference and diminishes the heat brought into the room. Among different air channels, a thickness of 100 mm performs best with a temperature difference between the inlet and outlet of about 45 °C. At 13:00 o 'clock, the maximum airflow rate of approximately 5.8 L/s is achieved for a thickness of 100 mm, whereas for thicknesses of 150 mm and 50 mm, the corresponding values are 4.9 L/s and 4.1 L/s, respectively. It is important to note that blindly increasing air channel thickness to raise indoor temperature is not a practical or reasonable engineering solution. The measured and numerical results can provide valuable reference value for the improvement and development of Trombe wall buildings in the future. [ABSTRACT FROM AUTHOR]

• A new research framework for identifying the key Ecological nodes was proposed. • Achieved dynamic analysis on ecological networks and their components. • Weighted complex networks have been used to obtain ecological network topology information with higher credibility. • Rethinking landscape function from the perspective of animal movement. Regional ecological security is a pressing issue in the context of escalating human-environment conflicts. Ecological networks(ENs), the fundamental tool for characterizing ecosystems, have enabled further quantitative analysis at the micro level by integrating with complex networks in recent years. However, most studies neglect the unreliability of unweighted complex networks and the dynamic characteristics of ENs. This paper takes the Sichuan Basin as the research area and adopts the following methods. Firstly, it integrates landscape ecology and ecosystem services to construct the ENs using Linkage Mapper. Secondly, it introduces the cost-weighted distance as the weight to build complex networks and identifies potential pivot ecological sources and key ecological corridors based on the topological features of the weighted complex networks in 2000, 2010, and 2020. Thirdly, it applies circuit theory to detect ecological pinchpoints and ecological barrier points within the corridors as priority areas for ecological conservation and restoration. The results show that the ENs in the study area are denser on the northern and southern sides, and some ecological corridors change direction due to variations of resistance surfaces and landscape morphology. Through dynamic analysis of the weighted complex networks, 27 potential pivot ecological sources and 25 key ecological corridors are identified; then, 28 priority conservation areas and 10 priority restoration areas within these ecological corridors are extracted based on circuit theory. The study reveals a certain correlation between the distribution of ecological nodes and water bodies. Furthermore, comparing the weighted and unweighted complex network, we find that the weighted complex network is more reasonable, with 64.2% of ecological sources showing lower betweenness centrality than that in the unweighted network, reflecting the obstacles that urbanization poses to ecological networks. This study explores the impact of constantly changing resistance surfaces on the overall ENs and their components through dynamic analysis. The evolving topological features reflect the feedback of the ENs to external environmental changes, as well as the dynamic characteristics of the real ENs. Therefore, the findings of this study provide valuable references for ecological conservation and governance efforts in Sichuan Basin, promoting regional ecological security and the advancement of ecological civilization. [ABSTRACT FROM AUTHOR]

• Geological disasters in hilly areas are related to Land-Use and Land-Cover Changes. • The number of geological disasters in the cultivated land area is the largest. • The point density of geological disasters and vegetation coverage is limited. • Geological disasters are more likely to occur in the period of heavy rainfall. • The closer geological disaster to river, the greater probability/scale of occurrence. Sichuan hilly area is located in southwest China, which have many hilly area, is a densely populated, economically active, frequent geological disasters area. In this paper, Neijiang City in the region is taken as the test sample. This article, which analyzes Land-Use and Land-Cover Changes (LUCC), meteorological and hydrological data from 2015 to 2020, takes Neijiang City in this region as the research object. We explored the relationship between geological disasters such as collapse and landslides that often occur in the natural ecological environment with LUCC and meteorological and hydrological factors, using GIS spatial analysis and statistical analysis methods. The research results indicate that geological disasters mainly occur in farmland areas. The density of geological disaster points is highest within urban areas, making them the most prone to geological disasters. Geological disasters are more densely distributed in the area within 600 to 800 m from the river. There is a strong correlation between the average rainfall amount and the probability of geological disasters occurring. This study provides a scientific basis for the geological disaster risk assessment, prevention and control in this region. It has certain reference significance for the ecological environment governance, land resources planning and management in other similar regions. [ABSTRACT FROM AUTHOR]

• The spatial competitions contribute to the evolution of rural residential land (RRL). • RRL in study area is characterized with "dense in the west and sparse in the east". • Evolution of RRL is impacted by macro factors and micro housing selection. • Spatial distribution pattern of RRL will remain nearly unchanged in the long run. Spatial systematic competition definitely contributes to rural residential evolution. Rural residential land of mountainous economic circle is generally hard to govern due to the disturbances from natural factors and economic activities. This study established a framework and adopted Kernel Density Estimation (KDE), Exploratory Spatial Data Analysis (ESDA), Geographical detector (Geo-detector) and Patch-generating Land Use Simulation (PLUS) to examine the evolution characteristics, drivers and trends of rural residential land of Chengdu-Chongqing Economic Circle(CCEC). Our research uncovered that: 1) The competitions between rural living space (RLS), rural production space (RPS) and rural ecological space(RES) substantially contribute to the evolution of rural residential land according to the conceptual framework, and the evolution in mountainous economic zone is greatly impacted by the close coupling interaction of macro driving factors and micro farmers' housing selection. 2)The characteristics of rural residential evolution of Chengdu-Chongqing area presents "dense in the west and sparse in the east", and the majority of which are concentrated in Sichuan Basin and Chengdu plain area. 3) Although the size of rural residential land in Chengdu-Chongqing area presents a fluctuant downward trend according to the simulation results, the spatial distribution pattern will remain nearly unchanged in the long run. 4) Rural residential evolution reflects the interactional process of muti-factors, as well as the matching result between man-land relationship and regional development goals under the land use policies. Overall, The theoretical and empirical research form the perspective of spatial competition in this paper provides a new idea for future studies on the evolution of rural residential land. [ABSTRACT FROM AUTHOR]

• The factors that affecting urban carbon emissions efficiency (CEE) are explored. • The carbon emissions of 282 cities are estimated with the aid of nighttime light data. • Urban CEE has significant and positive spatial spillover effects. • Industrial agglomeration and collaboration are key to green production efficiency. This paper explores the factors that improve the efficiency of urban carbon emissions. Based on nighttime light data, the carbon emissions of 282 cities in China from 2004 to 2018 are estimated, and the carbon emission efficiency (CEE) is measured. The spatial autocorrelation results show that CEE in Chinese cities has significant and positive spatial spillover effects. The LISA low-low type cluster area of CEE presents an evolutionary trend of westward migration, and eventually formed two low-efficiency centers in the Central Plains city group and the Sichuan-Chongqing city group. The empirical results of the spatial Durbin error model show that urban population expansion, economic growth and R&D investment have effectively improved CEE, but industrial scale and agglomeration adversely affect CEE. In addition, human capital investment and foreign investment have not exerted their due green growth effects. Manufacturing agglomeration had a negative impact on local CEE, but had a warning effect on neighboring regions. Different from the manufacturing industry, the agglomeration of producer services industry can bring significant improvement to CEE, accompanied by a demonstration effect which can promote the CEE in adjacent regions. Further, this paper finds that developing the synergy between manufacturing and producer services industries can significantly restrain the negative effects of industry on CEE. This paper enriches the performance evaluation framework of low-carbon city development in theory, and varies the situations that previous researches only concerned about carbon emissions while ignoring emissions efficiency. This paper is a beneficial policy practice of the coordinated development of economic growth and ecological environmental protection in the regional coordinated development mechanism, which indicates that strengthening industrial collaboration can effectively improve the efficiency of green production in cities. [ABSTRACT FROM AUTHOR]

• A zoning method based on ecological indicators and economic indicators is applied. • Ecological and economic situations are highly correlated with topographic conditions. • The coupling coordination degree(CCD) between ecology and economy is calculated. • Economic development is highly positively correlated with CCD. • Targeted regional sustainable development strategies are put forward. The coordinated development of ecology and economy is one of the key issues of sustainable development. A full understanding of the relationship between ecology and economy is necessary for the coordinated development of the two. This paper takes Sichuan Province as the research area and county-level administrative districts as the research unit. Based on the medium value of the ecological quality index and economic growth index of each unit, Sichuan Province is divided into dual pressure zones (DPZ), economic backward zones (EBZ), ecological crisis zones (ECZ), and coordinated development zones (CDZ) and the coupling coordination degree (CCD) of each unit is studied. The results show that: (1) On the whole, the eastern part of Sichuan Province has a better level of economic development, and the southern part of the western region has a higher ecological quality. The ecological quality and economic growth pattern are highly correlated with topographical conditions. (2) The distribution characteristics of the four types of partitions are significantly different. The EBZ are more distributed in the western and southern of Sichuan Province, the ECZ are more distributed in the eastern, the DPZ and CDZ are relatively more sporadic. More than 90% of the partition changed zones are distributed in the eastern area. (3) The CCD of more than 95% units belongs to moderate coordination and high coordination. The overall CCD of the four types of zones has shown an upward trend from 2010 to 2015. Based on the results, Sichuan Province should follow the path of clear waters and green mountains are as good as mountains of gold and silver, and targeted sustainable development suggestions for DPZ, EBZ, ECZ, and CDZ are put forward. This paper provides guidance for formulating regional sustainable development strategies, especially in areas with unbalanced development due to congenital topographical conditions. [ABSTRACT FROM AUTHOR]

Hydropower is an essential resource for the future clean energy transition, in which an accurate assessment of the hydropower cost is vital for promoting its share in the energy market. The purpose of this paper is to comprehensively reassess the cost of hydropower from a new perspective, in which the total static investment cost of a hydropower base is allocated among multiple functions. An allocation coefficient is proposed based on indicators of economic value and physical volume of multi-function hydropower bases. The economic value of each function is evaluated using approaches including the shadow project, market valuation, and emergy evaluation methods. Meanwhile, the physical volume is obtained through a multi-objective optimization of cascade reservoir operation considering an ecological constraint. Four main functions consisting of hydropower generation, flood control, agricultural irrigation, and residential water supply of hydropower bases in Sichuan are investigated. The results show that the allocation coefficients under both economic and physical indicators vary significantly among hydropower bases, and change slightly over the years. The average comprehensive allocation coefficient of hydropower is 57.26% (range from 29.83% to 77.41%), and the hydropower cost can be reduced by 59% from the current level. The reassessed hydropower cost can lay a solid foundation for market pricing. Attention should be paid to the multi-functionality characteristics of hydropower bases to achieve fair sharing of cost and benefit. • A new approach is proposed from the perspective of allocation among multiple functions for hydropower cost assessment. • A comprehensive allocation coefficient combining economic and physical indicators has been developed. • The indicator of storage capacity is expanded based on the multi-objective optimization of cascade reservoir operation. [ABSTRACT FROM AUTHOR]

Since the Guideline of Strengthen Preservation and Development of Traditional Village enacted, the traditional villages gradually gain academic concern and many achievements are acquired. But the study about outdoor wind environment is still insufficient. In this paper, the outdoor wind environment of Liyuanba Village in Bazhong City of Sichuan Province – a typical traditional village in the northeastern Sichuan Basin, is simulated by CFD methods. According to the simulation result, the outdoor wind environment in winter is comfortable for people in general, but there are still eddies and corner flows in some areas. To improve the outdoor wind environment, the suggestions such as changing the direction of courtyard and building are put forward. Furthermore, the optimization is also simulated and these two simulation results are compared in the end. [ABSTRACT FROM AUTHOR]

• Microstructures of the outcrop/core kerogen were systematically characterized. • Differences in chemical structure between the outcrop/core kerogen were identified. • Realistic 2D/3D molecular models of the outcrop/core kerogen were constructed. • Validity of the proposed molecular models was verified by gravimetric adsorption. • Effect of the kerogen microstructure on CH 4 adsorption behavior was investigated. It has been known that adsorbed gas, mainly CH 4 , serves as the dominant source of shale gas yield in the middle and later stages of reservoir exploitation. Therefore, it is of great significance to study the microstructure of kerogen (organic matter rich in shale) and its effect on CH 4 adsorption characteristics. In this paper, for the first time, a comparative study was conducted to experimentally characterize the microstructure of both outcrop and core kerogen samples from Longmaxi Shale, Sichuan Basin, SW China, using 13C NMR, FTIR, and XPS. Great differences in the chemical structure such as carbon skeleton (e.g. , aromaticity, aliphatic branch) and heteroatoms (e.g. , distribution and proportion of various types of functional groups) between the two kerogen samples have been identified. Molecular models of the outcrop and core kerogen samples were constructed based on the experimental data, that is, C 237 H 219 O 21 N 5 S 4 for the former and C 239 H 175 O 27 N 5 S 4 for the latter. CH 4 adsorption isotherms obtained from gravimetric adsorption test and molecular simulation using proposed kerogen molecular models are in reasonable agreement with each other, especially at low-pressure range. Interestingly, the adsorption capacity of CH 4 in the core sample is found higher than that in the outcrop sample under the same condition, indicating the effect of kerogen microstructure on CH 4 adsorption behavior. As a result, to precisely evaluate the adsorbed gas content in shale gas reservoirs, it is strongly recommended to use a core sample rather than an outcrop sample. [ABSTRACT FROM AUTHOR]

• Three ANN methods are utilized in the process of force finding of cable domes. • Four finite element models of cable domes are established to validate the feasibility of ANN-aided force finding methods. • Prestress of cable domes with single and multiple self-stress states can be accurately predicted by ANNs. Force finding of cable dome structures is a sophisticated and indispensable procedure in terms of their unique structural stiffness derived from self-equilibrium stress to the tension cables and compression struts. Owing to the limitation of traditional force finding methods, the process is often time-consuming and challenging. To address this issue, a general machine learning-aided computational framework for conducting a reliable force finding process is established. Several commonly used force finding methods for cable dome structures are summarized at first. Then the paper introduces the fundamental principle of the artificial neural network (ANN) methods including Back Propagation neural network (BPNN), Radial Basis Function neural network (RBFNN) and General Regression neural network (GRNN), and proposes to combine ANN methods with finite element analysis (FEA) to the force finding of cable dome structures. Additionally, the Geiger, Kiewitt, Levy and hybrid cable dome structures (Tianquan Gymnasium in Sichuan Province, China) are taken as examples of case validation, solved by ANN-aided force finding methods respectively. The results indicate that the proposed computational framework is capable of searching for the feasible prestress whether or not considering the external load such as self-weight. Among ANNs in this case study, GRNN can be applied in the calculation of not only basic cable dome structures with both single and multiple integral self-stress states, but also intricate cable dome structure in practical engineering projects with optimal accuracy and efficiency. [ABSTRACT FROM AUTHOR]

• An optimization of eco-industrial structure considering economy-society-ecology. • A multi-objective optimization model meeting three dimensional objectives is built. • The hybrid ACO-PSO algorithm is applied to solve the model. • Optimized scenarios realize overall development of economic-social-ecological benefits. • The optimized scenarios with different tendencies promote different benefits. The establishment of ecological economic system has become the key to realize the transformation of China's economy from high-speed development to high-quality development. This paper considers the multiple goals of economic, social, and ecological benefits to achieve sustainable development. Firstly, it establishes an indicator system affecting economic, social, and ecological benefits to guide the construction of the subsequent model. Secondly, this study constructs a multi-objective optimization model for ecological industrial structure. According to the different emphasis of objectives, a hybrid approach based on ant colony optimization and particle swarm optimization (ACO-PSO) is implemented to solve the optimal solution set of feasible schemes. Finally, Sichuan Province is selected as the case study area, and three scenarios including economic oriented scenario, employment protection scenario and environment-friendly scenario are screened and analyzed. The results show that: (1) After reasonable optimization and adjustment of the industrial structure, it realizes the overall development of economic benefits, social benefits, and ecological benefits. The comprehensive benefits of sustainable development have been significantly improved. (2) The optimized scenarios with different tendencies promote different benefits. Decision makers can make better choices based on the diverse needs of the different development stage. [ABSTRACT FROM AUTHOR]

The construction and operation of the Sichuan-Tibet railway require constructing extensive supporting facilities along its route. Sichuan-Tibet transportation corridor features high mountains and deep valleys where land resources suitable for such purposes are very limited. As a result, safe utilization of the torrential fan along the railway becomes essential. Focus on buildings at the torrential fan, this paper aims to develop a vulnerability model that can assess their maximum potential damage and support the planning and development of the torrential fan. The model was developed based on 51 building damage data collected at 11 torrential fans. The hazard intensity was defined by the geometric configuration of torrential fans and the location of assessed buildings. In addition, a physical experiment was carried out to study the shielding effect of building groups. The results show that the shielding effect range is about 25 times the building size, and the maximum reduction in impact force can reach 60%. The advantage of the proposed vulnerability assessment model is that it only requires the spatial information of the site that can be easily derived from the satellite image. In addition, the model can reflect the complex torrential process and the shielding effect of building groups. This study provides an alternative approach to building vulnerability assessment. It supports the planning and development of torrential fans when constructing the supporting facilities for the railway construction and operation. • The intensity of torrential hazards at each building is defined by the fan's geometric configuration and the assessed building's position. • The proposed model is easily adaptable since the required data is widely accessible from the satellite image. • The shielding effect of building groups when subject to torrential hazards is considered in this vulnerability assessment model [ABSTRACT FROM AUTHOR]

The terrain along the Tibet Railway is primarily steep mountains and valleys with complex geological structures. The occurrence of the Mainling earthquake indicates that the intensity of seismicity in the eastern structural junction area has strengthened, and the potential risk of earthquake-induced disasters such as landslides and debris flows is also increasing. The earthquake engineering community generally recognizes that the prediction of near-field strong ground motion can reduce the disasters caused by future large earthquakes and can guide earthquake prevention, disaster reduction and seismic design along the Sichuan–Tibet railway. The M6.9 Mainling earthquake affected the stability of Sedongpu Glacier near the epicentre. A glacier avalanche occurred under the coupling of multiple factors, including post-earthquake and precipitation events. The waveform and response spectra of a strong earthquake are key input parameters for investigating the seismic triggering mechanisms of landslides and glacier avalanches and accurately reproducing the dynamics of such disasters. In this paper, the concept of the equivalent Green's function is introduced, and various source parameter uncertainties are fully considered. The waveform and response spectra of the Mainling earthquake at Sedongpu Glacier are simulated, and the most likely seismic waveform is comprehensively assessed from multiple perspectives. This work can provide reliable acceleration waveform input for the analysis of ground motion damage and the study of earthquake-induced disaster mechanisms at important locations along the Sichuan–Tibet railway and provide a scientific reference for earthquake prevention and disaster reduction along the railway. • The concept of equivalent Green's function is proposed. • The waveform containing many practical and complex information for seismic damage analysis • It expands the application range of empirical Green function method. • It could help to study the mechanism of earthquake induced geological hazards. [ABSTRACT FROM AUTHOR]

This paper develops an improved three-dimensional sphere discontinuous deformation analysis (SDDA) model and uses UAV-based photogrammetry to enable SDDA to numerically analyze potential long-runout debris flows in Zheduotang area along the Sichuan-Tibet railway. First, the original SDDA is improved by proposing a sphere-sphere bonding algorithm to bond spheres with tetrahedral layout to form four-sphere clusters to approximate non-sphere particles in debris flow. Second, the capacity of the improved SDDA is verified by comparing modelling results with four groups of laboratory tests of granular flow. Third, UAV-based photogrammetry is used to obtain the real morphology of the extremely complex terrain surface of Zheduotang area which is finally transferred into a large number of triangular faces as the fixed boundary faces of SDDA. Then, three potential debris flow scenarios on this terrain surface are numerically studied, and some suggestions for engineering disaster prevention are drawn. Model performance shows that, the improved SDDA is a feasible tool to simulate debris flows. With the help of UAV-based photogrammetry, it shows significantly helpful for geohazard prevention for infrastructures in mountainous areas like the Sichuan-Tibet railway. • An improved sphere discontinuous deformation analysis model is proposed. • The validation of the improved model in debris flow simulation is verified. • UAV-based photogrammetry to parameterize the extremely complex terrain surface of mountainous area is used. • Engineering-scale long-runout debris flow simulations are carried out. [ABSTRACT FROM AUTHOR]

Carbon emissions in air travel have attracted widespread attention with the fast development of the aviation sector. Currently, biofuel usage has the potential to curb these emissions due to the bottleneck of other aircraft emission reduction technologies. This paper studies carbon tax policy-induced air travel carbon emission reduction and biofuel usage in China considering the interactive relationship between an authority and multiple airlines by a bi-level model and an interactive solution approach. Then a case study based on airlines from southern China's Sichuan Province is conducted to explore useful insights, with scenario analyses being performed. The computational results indicate that the policy could be useful for air travel carbon emission reduction and biofuel usage improvement in China. These results and analyses provide insights to the authority for the tradeoffs between policy equity and carbon emissions reduction effectiveness, and airlines for profitability. • Carbon tax policy-induced air travel carbon emission reduction in China is studied. • A bi-level model considering interaction of an authority and airlines is developed. • Trade-off between the effectiveness and equity of the carbon tax policy is analyzed. • A case study based on airlines in China is provided to explore useful insights. • The policy plays a vital role in carbon emission reduction and biofuel usage. [ABSTRACT FROM AUTHOR]

The 20 April 2013 Lushan earthquake with a magnitude of M s 7.0 induced widespread landsliding along the southern segment of the Longmen Shan fault zone. This paper presents a preliminary analysis of the characteristics of these co-seismic landslides triggered in an area of 13,323 km 2 . A total of 3810 individual landslide points were identified through an intensive field investigation and from digital aerial photographs taken after the Lushan earthquake. To facilitate the more detailed analysis on the areal frequency of co-seismic landslides as polygons, we selected an area of 732 km 2 around the epicenter that had the highest density of co-seismic landslides. The sizes of the landslides are, in general, much smaller than those that were triggered by the 2008 Wenchuan earthquake. The most common types of landslides in the study area were rock falls and shallow, disrupted landslides from steep slopes, which typically involved the top few meters of weathered bedrock and colluvium. In this study, the relation between the landslide distribution and five main factors was analyzed: fault proximity, epicenter proximity, peak ground acceleration (PGA), slope angle, and lithology. Our study results show that the landslide concentration tends to decrease with distance from the seismogenic fault, and the highest landslide concentration is located within a distance of 5 km. Regarding the distance to the epicenter, the largest landslide density is found at a distance between 5 and 10 km. The landslide concentration also increases with increasing slope angle until a maximum for the slope class 45°–55°. In addition, results show that slopes consisting of deeply weathered and fractured sandstones and mudstones were the most susceptible to co-seismic landslides. In this study, we found that the location of the hanging wall and the footwall of the fault did not seem to have an important effect on the landslide distribution. This is in contradiction to what has been reported in other earthquake areas such as the Wenchuan area. [ABSTRACT FROM AUTHOR]

On April 20, 2013, an earthquake of M7.0 occurred in Lushan, Sichuan province, China. This paper investigates the coseismic ionospheric anomalies using GPS (Global Positioning System) data from 23 reference stations in Sichuan province that are a part of the Crustal Movement Observation Network of China (CMONOC). The recorded results show that a clear ionospheric anomaly occurred within 15 min after the earthquake near the epicenter, and the occurrence time of the anomalies recorded by various stations is related to the distance from the epicenter. The maximum anomaly is 0.25 TECu, with a 2 min duration and the distance of the recording station to the epicenter is 83 km. Acoustic waves generated by the crustal vertical movement during the earthquake propagate up to the height of the ionosphere lead to the ionospheric anomaly, and the propagation speed of the acoustic wave is calculated as 0.72 ± 0.04 km/s based on the propagation time and propagation distance, consistent with the average speed of sound waves within a 0–450 km atmospheric height. [ABSTRACT FROM AUTHOR]

• CO 2 and SRB were the main factors of shale gas pipeline corrosion and perforation. • Pre-cultured with culture medium increased the corrosion rate of the steel, and SRB catalytic corrosion process. • CO 2 promotes bacterial film formation and accelerates corrosion. • Bacterial enrichment is the main cause of pitting corrosion. In the shale gas field in southern Sichuan Basin, the corrosion-induced failure has been observed. In this paper, first, the corrosion phenomenon was analyzed. Second, the causes of corrosion were analyzed thoroughly from the aspects of corrosive environment, materials, and corrosion products. Finally, the field water environment was simulated, and the result showed the following: SRB is one of the main causes of corrosion and perforation of shale gas pipelines, bacterial enrichment is the primary reason for local corrosion, and CO 2 promotes the formation of bacterial film and accelerates corrosion. [ABSTRACT FROM AUTHOR]

• Seismic vulnerability analysis of a masonry pagoda through FE simulations in Abaqus. • Good agreement between FE modal analysis and cantilever beam first mode formula. • Sensitivity analysis on the CDP material parameters for Pushover Analyses POs. • NLDAs that confirmed the collapse acceleration results given by POs. • Slenderness influence studied using taller/shorter pagodas with 3D models artificially created. As an important historical building type for human beings, ancient masonry pagodas have key research significance. They are widely diffused in China, and they are tower-like masonry structures, usually massive and tall. This paper takes the Longhu pagoda as a case-study: it was built in 1342 CE, and it is the only masonry pagoda from the Yuan Dynasty. It is located in the Sichuan Province (China), it has a square plane, and the height is about 33 m. This construction severely suffered the so-called "2008 Sichuan Earthquake". A full 3D model of the Longhu Pagoda has been obtained and subsequently meshed. The FE software Abaqus/CAE has been used for carrying out static analyses, pushover analyses and non-linear dynamic analyses. The material non-linearities have been taken into consideration employing the so-called Concrete Damage Plasticity (CDP) model available in Abaqus. Modal analyses have shown that FEM results and simplified cantilever model results may agree. Pushover analyses (POs) have been performed under different load conditions and along the four principal bending directions to estimate the global capacities and the corresponding collapse mechanisms. Non-linear dynamic analyses (NLDAs) allowed putting in evidence the accuracy of the results provided by the pushover analyses; besides, they gave helpful information about the crack propagation, confirming the damage reported on-site after the 2008 earthquake. The state of damage found and the related failure mechanisms have been deeply commented. Moreover, some sensitivity analyses have been performed to study the influence of some material parameters on the pushover results. Furthermore, two fictitious 3D models of the pagoda have been created by doubling and removing two floors to investigate the influence of the tower slenderness. The before mentioned analyses have also been performed on such models, and the impact of the slenderness on this structural typology has been studied. Finally, the kinematic theorem of limit analysis has been applied, and some values of collapse acceleration have been consequently computed using different a-priori established collapse mechanisms. The results have been compared with FE simulations results, and the ability of limit analysis to quickly predict the seismic vulnerability has been discussed. [ABSTRACT FROM AUTHOR]

Most developing countries in the world face the common challenges of reducing air pollution and advancing the process of sustainable development, especially in China. Air pollution research is a complex system and one of the main methods is through numerical simulation. The air quality model is an important technical method, it allows researchers to better analyze air pollutants in different regions. In addition, the SCB is a high-humidity and foggy area, and the concentration of atmospheric pollutants is always high. However, research on this region, one of the four most polluted regions in China, is still lacking. Reviewing the application of air quality models in the SCB air pollution has not been reported thoroughly. To fill these gaps, this review provides a comprehensive narration about i) The status of air pollution in SCB; ii) The application of air quality models in SCB; iii) The problems and application prospects of air quality models in the research of air pollution. This paper may provide a theoretical reference for the prevention and control of air pollution in the SCB and other heavily polluted areas in China and give some1inspirations for air pollution forecast in other countries with complex terrain. [Display omitted] • Current situation of air pollution in the Sichuan Basin of China is reviewed. • The development and classification of air quality models are summarized. • Application of air quality models in the study of Sichuan Basin air pollution are discussed. • Problems in the application and future research directions of air quality models are provided. [ABSTRACT FROM AUTHOR]

In 2008, the Wenchuan earthquake triggered many large landslides with rapid movement and long runouts, resulting in a great number of casualties. Although there have been many studies of the geographical features and initiation mechanisms of some catastrophic landslides, the movement mechanisms for many remain unclear. In this paper, we present a case study of a large landslide (debris avalanche) triggered by the 2008 Wenchuan earthquake in the Donghekou area, Sichuan Province, China. We made detailed field surveys of the geographical features of the landslide and carried out subsurface investigations of the landslide deposits using microtremor array measurement and electrical resistivity tomography (ERT). Based on the observed surficial features, shear-wave velocity (Vs) profiles and 2D electrical resistivity profiles of the landslide deposits, we estimated the possible thickness of landslide deposits at different locations, and also analyzed the possible landsliding mechanisms. We inferred that this landslide resulted from retrogressive failures on the source area, and the displaced landslide materials underwent transitional spreading with further entrainment of debris along the travel path. Multiple mud waves might have been formed in the substrate soil layers along the travel path due to the entraining of landsliding materials, and the landsliding materials might have presented channelized movements, indicating that different parts may have moved at different speeds. This kind of transportation mechanism may provide information for elevating the numerical simulation of landsliding, and also for reuse of deposit area of large landslides. • Donghekou landslide is a debris avalanches resulted from retrogressive failures. • The boundary between the landslide deposits and bedrock had been identified. • Main surges with mud waves on the bottom of landslide material had been identified. • Channelized sliding may have occurred within the landsliding materials. [ABSTRACT FROM AUTHOR]

Coupled human and natural system research is an urgent issue in the Anthropocene. However, this has not yet been conducted from the perspective of multiplex networks, which are a powerful tool to elucidate the interactions in human-natural systems. This paper establishes a framework of human-water multiplex networks (HWMNs) to explain the combined effects of human-water interactions in the Yangtze River basin. The spatial linkages and the status of each province in the Yangtze River basin can be characterized through the index of network flow and topology. Research demonstrated that the highest import flow of the virtual water environment capacity flow in the Yangtze River Basin is to Jiangsu Province, at 16.2 thousand t. The highest export flow in the Yangtze River Basin is from Shanghai city, at 33.2 thousand t. The control power of Shanghai city over Sichuan Province accounts for 56.59% of the water resources, which is the highest value and can be recognized as one type of telecoupling of water resources. The provinces in the delta of the Yangtze River basin, including Shanghai city, Jiangsu Province and Zhejiang Province, benefit the most from economic trade. The community structure of the virtual water environment capacity flow is highly consistent with the geographical distribution of the Yangtze River basin. Comprehensive research methods combined with network flow analysis and network topology analysis provide more general results. The microenvironmental effect of indirect pollutant discharge is uncovered through HWMNs. This research can provide a more connected view of integrated water management. Image 1 • A framework of HWMN is established to reveal the combined environmental effects. • The key provinces are revealed through the network flow analysis and topology analysis. • The provinces in the Yangtze river delta obtains most of the water environment benefits. • The environmental effect of the indirect pollutant discharge through HWMN is revealed. [ABSTRACT FROM AUTHOR]

With the large-scale exploitation of marine gas reservoirs in Sichuan, a casing becomes thin, deformed, cracked or even broken after long-term downhole service, seriously restricting the working life of gas wells. To assess the safety of in-use casings, a three-level assessment model of casings is established, which provides a systematic screening and analysis method for the safety evaluation of casings in marine gas reservoirs. By means of factor analysis, feasibility demonstration and result comparison, the three-level assessment is proved to be suitable for casings. The assessment shows that the safety margin of casings rises step by step. The casing with high safety margin can be eliminated by the first level assessment to improve the efficiency and economy of the process, and then the scope of the dangerous case can be reduced by the second level assessment. Finally, the dangerous case and its real safety margin can be identified by the third level assessment to avoid increasing of the maintenance cost because of the excessive safety margin. Therefore, accurate identification and cost reduction can be achieved by three-level assessment. • This paper develops a three-level assessment for casings. • By means of factor analysis, feasibility demonstration and result comparison, it is proved that the three-level assessment is suitable for casing. • In casing three-level assessments, the safety margin of the results rises gradually. Accurate identification and cost reduction can be achieved. [ABSTRACT FROM AUTHOR]

Using the method of isothermal dissolution equilibrium, stable phase equilibria of unreported strontium-containing systems LiCl–NaCl–SrCl 2 –H 2 O and LiCl–KCl–SrCl 2 –H 2 O at 298 K have been studied in accordance with the compositions of the underground brine in western Sichuan Basin. The experimental results show that there are no solid solution and complex salt in two quaternary systems. The phase diagram of quaternary system LiCl–NaCl–SrCl 2 –H 2 O consists of two invariant points, five isothermal dissolution curves and four crystallization regions. The quaternary system LiCl–KCl–SrCl 2 –H 2 O belongs to a simple type and the phase diagram consists of two invariant points, five isothermal dissolution curves and four crystallization regions. The solubilities of salts in the above systems were accurately calculated with Pitzer electrolyte solution theory. It was found that the calculated phase diagrams coincided basically with the experimental phase diagrams by evaluated the accuracy through the experimental results. Meanwhile, the applicability of Pitzer parameters selected in this paper was validated. [ABSTRACT FROM AUTHOR]

The Sichuan Basin (SCB) has suffered from serious ozone (O 3) pollution in recent years, especially in summer. However, the formation and evolution mechanisms of O 3 pollution in the SCB remain poorly understood. In this paper, we comprehensively investigated the causes of elevated ozone concentrations in Chengdu in July 2017 with a combination of field measurements and the WRF (Weather Research and Forecasting)-CMAQ (Community Multi-scale Air Quality) model simulations. The ozone formation characteristics of continuous O 3 episodes and non-O 3 episodes were compared. Higher temperature (T), stronger solar radiation (SR), lower relative humidity (RH) and weaker winds were conducive to O 3 formation during ozone episodes. The O 3 concentration during O 3 episodes (202.6 μg m−3) was significantly higher than that during non-O 3 episodes (122.7 μg m−3), attributable to the higher volatile organic compounds (VOCs) concentration (34.0 ppbv compared with 27.5 ppbv) despite comparable NO x concentrations during O 3 episodes. The results of positive matrix factorization (PMF) for ambient VOCs showed that gasoline vehicle exhaust and solvent usage were the dominant sources during the month. However, the increasing source attributions from the petrochemical industry and biogenic emissions were responsible for the elevated VOCs concentrations during O 3 episodes. The relative contributions of local emission and regional transport to ozone were quantified during two O 3 episodes by conducting numerical sensitivity experiments. In the first episode, namely, the "O 3 -regionally transported" pattern, high ozone concentration in Chengdu was primarily due to the regional transport of ozone and ozone precursors through vertical mixing and horizontal advection from upwind areas (central and eastern SCB) when easterly or southeasterly winds prevailed over the SCB. In contrast, in the second episode, namely, the "O 3 -locally dominated" pattern, high local emissions under favorable meteorological conditions are the major reason for elevated ozone concentration. The process analysis results from the CMAQ model suggested that the vertical transport of O 3 that formed at the upper levels from intense gas-phase chemistry reactions was a dominant contributor to diurnal O 3 enhancement in O 3 episodes by 45 μg m−3, while horizontal transport contributed more than 80% of the nocturnal O 3 concentration. This study provides a better understanding of ozone photochemical formation and regional transport mechanisms in the SCB under complex terrain conditions, and contributes to ozone pollution prevention in other basins around the world. • Two high O 3 episode in Chengdu was simulated using the WRF-CMAQ modeling system. • Ozone and precursors from upwind-polluted areas are crucial to high ozone episodes in Chengdu. • Vertical mixing plays an important positive role to surface elevated ozone in Chengdu. [ABSTRACT FROM AUTHOR]