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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]

• Eleven high-quality heat flow data were added to the Sichuan Basin. • Based on the geological model, the temperature distribution of the Qixiamaokou Formation in southern Sichuan Basin was calculated. • The distribution and reserves of geothermal resources in the Qixiamaokou Formation in southern Sichuan were evaluated. The southern Sichuan Basin is an abnormal area of high present geothermal fields in the Sichuan Basin. It is a favorable area for the development of geothermal resources in the Sichuan Basin. But its evaluation of geothermal resources is lagging, which has severely affected the development of geothermal resources in the southern Sichuan Basin. In the paper, firstly, based on the temperature data of wells, the geothermal gradients and heat flows of typical wells in the study area were calculated, and the temperatures at the top and bottom of the reservoir in the Qixia-Maokou Formation were calculated using a one-dimensional steady-state heat conduction equation. Then, geothermal resource intensities and reserves of the Middle Permian Qixia-Maokou Formation in the southern Sichuan Basin were evaluated by using a method for rapidly calculating geothermal resources in sedimentary basins by multi-data fusion. Finally, suggestions for geothermal development were proposed. The results show that the geothermal gradient and heat flow values in the southern Sichuan Basin range from 15.6 to 33.70 °C/km and 49 to 85 mW/m2, respectively, and the temperature of the reservoir in the Qixia-Maokou Formation ranges from 50 to 120 °C. The geothermal resources are 3.09 × 1021 J, equivalent to 105 billion tons of standard coal, and the recoverable resources are 6.18 × 1020 J, equivalent to 21 billion tons of standard coal. The development of demonstration projects will focus on the mid- to low-temperature geothermal power generation, geothermal grain drying and geothermal agriculture in the southwestern region of the southern Sichuan Basin. The research results can provide a resource basis for the development of geothermal resources in the southern Sichuan Basin. [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 natural hydraulic connections between cascade hydropower may make hydraulic and electric connections mismatch after the market clears. Aiming at relieving the contradiction between water surplus and water shortage after market clearing, this paper proposes a new market clearing method considering the coupling relationship between water and electricity. And the method is verified by the simulation of a virtual spot market consisting of eight stations in Sichuan Province, China. The main contributions of this paper lay on three aspects: firstly, a new index called water-electricity coupling degree (WCD) and its calculation method are proposed to measure the overall situation of water shortage and water abandonment in the clearing results. Secondly, a multi-objective clearing model for cascade hydropower stations is established with the goal of minimizing power purchase cost and maximizing WCD. Thirdly, a solution method combined with the characteristics of the clearing model is developed. The case results demonstrate that the built model increases the WCD value by 1.57 % and reduces the insufficient output and surplus water by 45.18 % without increasing the power purchase cost of the power grid; The proposed solution strategy lowers the complexity of the model and improves the solution efficiency, where the search space reduction and time period merging strategies can reduce the calculation time by about 3 % and 8 % respectively. The new clearing method provides a new idea for solving the uncoupling problem of water-electricity-price in the cascade hydropower spot market. • Propose a new index called water-electricity coupling degree (WCD). • Establish a multi-objective clearing model for cascade hydropower market. • Develop a model dimensionality reduction strategy for model solution. [ABSTRACT FROM AUTHOR]

The development and utilization of renewable energy sources can not only effectively reduce carbon dioxide emissions, but also provide access to electricity to more parts of the world. A standalone hybrid system based on renewable sources is a promising way to supply reliable and continuous power in remote areas to which the grid has not extended. This paper designs and investigates a photovoltaics (PV)-wind-hydropower station with pumped-storage installation (HSPSI) hybrid energy system in Xiaojin, Sichuan, China as case of study. HSPSI can use the available flow of the river and store surplus energy generated from wind and PV by pumping water from the lower reservoir to the upper one. From the perspective of the investors, the techno-economic index is usually used to design the PV-wind-HSPSI hybrid energy system which aims to find the optimal configure with maximum power supply reliability and minimum investment cost. The trade-off analysis between the two objectives is based on Pareto optimality theory by means of Multi-Objective Particle Swarm Optimization (MOPSO). Besides, this paper takes the curtailment rate (CR) of the wind and PV power into consideration due to policy requirements. The relationship between the two objectives under various CR are analyzed and compared. Several results can be obtained as follows: 1) Comparing with the PV-HSPSI and wind-HSPSI hybrid energy system, the levelized cost of energy (LCOE) of the PV-wind-HSPSI hybrid energy system can reduce by 32.8% and 45.0% respectively. 2) For the PV-wind-HSPSI hybrid energy system, the LCOE can be as low as 0.091 $/kWh when 5% LPSP can be acceptable. 3) The policy of CR is unfavorable for the investors which leads to a higher investment cost. 4) Particle Swarm Optimization (PSO) performs better than genetic algorithm (GA) and Simulated Annealing method (SA) with a least LCOE. 5) both MOPSO and weighted sum approach (WSA) have a good performance to find the Pareto fronts and its hypervolume indicator (HV) is calculated. • A real PV-wind-HSPSI hybrid system is designed in Xiaojin, Sichuan, China. • The curtailment rate is introduced into the techno-economic index. • The LCOE can be as low as 0.091 $/kWh when 5% LPSP can be acceptable. [ABSTRACT FROM AUTHOR]

The Sichuan Basin (SCB) and its surrounding mountainous areas have complicated topography, and the "Nocturnal Rainfall in the Basin (NRB)" and "Nocturnal Rainfall in the Mountainous Areas (NRMA)" are frequent. To further clarify the relationship and the interaction between the two types of "nocturnal rainfall" synoptic systems, the characteristics of the synoptic meteorology, thermodynamics, dynamics, and water vapor fields of the nocturnal precipitation process generated by two Mesoscale Convective Systems (MCSs) that originated from the mountainous area on the western side of the SCB on June 4, 2019 were analyzed and diagnosed in this paper. In addition, the WRF-LES model was used to simulate and analyze the macro and micro physical characteristics of two precipitation centers formed by the main system MCS1 in the center of the SCB and the mountainous areas around it. The results showed as follows. (1) Two MCSs originated from the mountainous area on the western side of the SCB were generated by the eastward movement of the low-pressure trough over the Tibetan Plateau (TP) coupling the higher Convective Available Potential Energy (CAPE) value with the unstable circulation of the upper level. They matured in the SCB and matured and split in the western end of Mt. Daba, respectively. (2) After splitting, the southern part of the sub-system MCS2 sank and moved south along the southern foot of Mt. Daba and uplifted the main system MCS1. After its explosive development, two precipitation centers with the characteristics of the NRB and NRMA were formed. (3) The vertical velocity, divergence, thermal helicity, and potential vorticity could be used as the thermodynamics and dynamics diagnostic quantities to indicate the occurrence and development of the two MCSs. The potential vorticity was an obvious precursory parameter compared with the other three. The water vapor flux divergence and moisture helicity could better indicate the vertical transport of water vapor in the systems. (4) The precipitation simulation result of the WRF-LES model on the main system MCS1 in the SCB was better than that on the sub-system MCS2 in the mountainous area on the northern margin of the SCB. In each MCS1 stage, the precipitation of the NRB was mainly induced by the cold cloud process (supplemented by the warm cloud process), while the precipitation of the NRMA was mainly induced by the warm cloud process. The combination of diagnostic analysis and numerical simulation could effectively promote an understanding of the relationship and interaction between the NRB and NRMA. • The relationship and interaction between nocturnal rainfall in Basin (NRB) and mountainous areas (NRMA) by MCSs were clarified. • A diagnostic analysis method was established to analyze evolution and roles of MCSs during NRB and NRMA. • Combination of diagnosis and simulation successfully revealed the macro and micro physical mechanism of NRB and NRMA. [ABSTRACT FROM AUTHOR]

In this paper, the potential seven sets of geothermal resources in the Sichuan Basin were evaluated by using a method for rapidly calculating geothermal resources in the sedimentary basins by multi data fusion, and suggestions on geothermal development and utilization are made based on the basic characteristics of abandoned wells in the oil and gas fields. The results show that the Sichuan Basin is rich in geothermal resources. The total resources of 7 sets of thermal reservoirs reach 4.26 × 1013 GJ, of which the Qixia-Maokou Formation has the largest potential geothermal resources, reaching 1.36 × 1013 GJ. The Permian Qixia-Maokou Formation in southern Sichuan Basin has the conditions to prioritize the development of geothermal resources and has the characteristics of the highest temperature of formation water and the largest current and cumulative water production. At the same time, according to the formation temperature of abandoned oil and gas wells, they are divided into two types of wells, and different geothermal resource utilization methods are proposed. The research results can provide a model for the evaluation of geothermal resources in sedimentary basins and a resource basis for the development of geothermal resources in the Sichuan Basin. Method diagram for fast calculation of geothermal resources in the sedimentary basins by multi data fusion. [Display omitted] [ABSTRACT FROM AUTHOR]

The existing research on the multiple fluid control valves to control the balanced exploitation of natural gas in horizontal wells lacks theoretical model support. On this basis, this paper established a flow rate and pressure model of the segmented horizontal well based on the fluid control valve. The model considers the throttling performance, installation position and opening adjustment step size of the fluid control valve for the first time. Next, systematically analyzed the mechanism of mutual influence of the opening and the position on the flow rate and pressure based on multiple fluid control valves. In addition, a novel method of using the dichotomy model to adjust the production of different production segments was proposed to analyze the horizontal wells of 15 production segments in Sichuan. It was found that when the opening adjustment step size is less than 5%, the natural gas production shows irregular changes, which makes it hard to effectively control the production of each segment. When the step size is 5%, the maximum production variation is 2.7%, which will have a more significant and meaningful effect on the exploitation of natural gas. Through seven iterations, the maximum production errors of high and low production segments are 1.3 % and 1.1 % respectively, both less than 2.7%. The research results verified the correctness of the theoretical model of segmented horizontal wells based on multiple fluid control valves. This research provided a theoretical basis for the opening control of multiple fluid control valves based on different production segments of horizontal wells. • Established a flow rate and pressure model of segmented horizontal wells based on the fluid control valve. • Found the minimum adjustment opening for the numerical simulation of the balanced exploitation in horizontal wells. • Proposed a novel dichotomous method to adjust the production of different segments in the horizontal well. [ABSTRACT FROM AUTHOR]

This paper examines how perceived social equity (distributional equity, procedural equity, and recognitional equity) affects acceptance of protected areas by local communities. We also consider the consequences of these perceptions on the behaviour of local people in relation to biodiversity conservation. Despite increasing importance being given to social issues in protected area management, there is limited evidence about the effect of perceived equity on local support for conservation initiatives. Questionnaires (mostly face-to-face interviews) were undertaken with 426 households living in and around the Giant Panda National Park, which lies across the Sichuan, Shanxi and Gansu provinces of China. Structural equation modelling revealed that local residents with positive perceptions of procedural and distributional equity were more willing to support conservation and engage in conservation behaviours. Surprisingly, perceived recognitional equity had no effect on acceptance and negatively impacted conservation behaviour. This highlights that, although it is essential to promote recognitional equity, the complexities around this must be considered further. The context (e.g. age, education, village of residence) moderates the relationships between procedural equity, distributional equity and local acceptance. We suggest that, in order to achieve better park-people relationships, in addition to addressing equity concerns, it is also necessary to implement supplementary measures, such as community co-management and benefit sharing with host communities. • Procedural and distributional equity facilitate acceptance of protected areas. • Recognitional equity has an intricate relationship with local support. • Perceived justice tends to be non-linear in relation to local support. • The location of communities influences local pro-conservation behaviours. • There is a need for a better understanding of the equity-acceptance relationship. [ABSTRACT FROM AUTHOR]

The parameters of fractures, such as fracture geometries, placement, and conductivity, are critical for the production of horizontal wells in tight gas reservoirs. Current studies on fracture parameter optimization, especially those using the optimization algorithms, are often based on the assumptions that the fractures are uniformly placed with equal length and conductivity. However, non-uniform designs of fracture spacing have been proved to be effective in reducing fracture interference as well as increasing the well production, especially with strong rock heterogeneity. In addition, most of the current literature focuses on identifying optimal hydraulic fracture geometries without considering the fracture propagation process, which may oversimplify the evaluation of completion cost and result in fracture geometries that cannot be realized in practice. In this paper, an automatic optimization process, which could efficiently couple the fracture propagation, is proposed to optimize the fracture parameters. The genetic algorithm (GA) with penalty function method is used to optimize the constraint and non-linear problem. A modified PKN fracture propagation model is established to quickly predict the hydraulic fracture geometries. Fracture locations and fluid injection volume are sequentially optimized with consideration of heterogeneous rock properties. Model parameters are taken from typical tight gas horizontal wells in Jinqiu gas field in Sichuan Province, China. The results show the importance of permeability on both fracture length and production in tight gas well. The lower the permeability, the more significant the production increase after fracture location optimization. More fractures tend to be placed in area with small permeability and fewer fractures are required in highly permeable regions. With an increase in rock heterogeneity, the distribution of fractures becomes more uneven. Conversely, increasing the number of fractures can lead to a more even distribution of fractures. More fluid should be injected in low-permeability regions according to the optimization results. The optimization method is applied to a practical tight gas well in Sichuan Basin and the cumulative gas production can be increased by 6.5% to 8% when compared with the initial uniform designs. • A modified PKN model is proposed for quick prediction of fracture propagation, validated against numerical simulations. • GA is used to optimize fracture locations by considering rock heterogeneity's impact on fracture propagation and production. • Sequential optimization of fracture placement and injection volume is conducted with its reliability verified. [ABSTRACT FROM AUTHOR]

As a result of the combined influence of multi-stage and multi-directional tectonic activities, the subsurface medium in complex structural areas can easily develop intricate fault systems with varying scales and directions. Post-stack seismic and azimuth-stack attributes have limited precision in recognizing such complex fault systems. In this paper, we propose an adaptive fault enhancement workflow in offset vector tile (OVT) domain based on anisotropy theory to improve the recognition ability of seismic data for multi-directional faults and minor faults. The vertical directions of fault strikes and tectonic strikes estimated by the gradient structure tensor (GST) can be used as sensitive observation azimuths of faults. At the same time, according to the anisotropic forward modeling and real data amplitude variation with offset (AVO) analysis of minor faults in marine shale of Wufeng-Longmaxi formations in Sichuan Basin, China, the incident angles with the largest difference between isotropic and anisotropic reflection coefficients can be used as sensitive incident angles of faults. A new fault enhancement seismic data can be reconstructed from the OVT gathers by traversing the sensitive azimuths and incident angles adaptively. The 3D model and real data indicate that the faults enhanced by the workflow we proposed are clearer in shape, smaller in scale, and richer in details, which is consistent with geology and well. • We propose an adaptive fault enhancement workflow in OVT domain. • The workflow considers the azimuth and incidence contained in OVT gathers. • We discussed the recognition ability of angle stack for minor faults. • The result of shale reservoir in Sichuan Basin is consistent with geology and well. [ABSTRACT FROM AUTHOR]

This paper presents a two-stage hybrid robust programming model that integrates multiple blood products scheduling and multiple casualty types evacuation under facility disruptions risk and casualty number uncertainty. The model seeks to maximize the rescue efficiency and minimize the total operations cost. Under a set of disruption scenarios, we adopt a scenario-based robust method to address disruption risks at temporary medical centres and two robust uncertainty sets to deal with uncertain casualty numbers. We propose a proximal bundle algorithm to solve large-scale instances of the proposed hybrid robust model approximately. Extensive numerical experiments show that: (i) the trade-off between model robustness and solution robustness can help the decision-makers determine an appropriate risk-aversion weight; (ii) compared with the corresponding stochastic and scenario-based robust models, the hybrid robust model can obtain more robust solutions with a slight increase in cost; (iii) the proximal bundle algorithm can produce near-optimal solutions within reasonable computational times; (iv) some model parameters have significant impact on the total cost, which can help decision-makers set the appropriate parameters to achieve the desired outcome. Finally, we also use the real data of the 2008 Wenchuan County Earthquake in Sichuan Province, China, to illustrate the application of the model. • An HRM is developed for jointly plan blood logistics and casualty evacuation. • The model considers facility disruptions risk and casualty number uncertainty. • A PB algorithm based on Lagrangian relaxation is proposed. • Experiment results show that HRM outperforms the SM and SRM. • Real data are used to illustrate the application of the model. [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]

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]

• Established an optimization model of the water-energy-land-carbon nexus. • Quantified carbon emissions and energy consumption in agroecosystems. • Introduced water availability and economic loss risk as uncertain parameters. • Balanced resource consumption, economic benefits and carbon emissions. • Improved sustainability and utilization of agricultural resources. In the context of global warming and resource scarcity, economic development and population growth are challenging the demand for water and land resources, and the complex relationship among water, land, energy and carbon dioxide makes it important that a process for efficiently managing water, energy, land and carbon dioxide in sustainable agricultural systems is developed. Therefore, considering the uncertainty of agricultural systems, this paper proposes a multiobjective optimization model for the sustainable management of water–energy–land–carbon dioxide systems that optimizes the allocation of water resources and land resources under the condition of minimizing agricultural carbon emissions and maximizing irrigation water productivity and energy economic productivity. The model uses the improved nondominated sorting genetic algorithm to address this issue, and the optimal resource allocation strategy is further obtained through the multiobjective decision model. This paper uses Sichuan Province, the main grain-producing region in Southwest China, as a case study to verify the effectiveness of the model and then provide a decision-making process for improving the utilization rate of agricultural resources and developing low-carbon agriculture. The results show that under the coordination of resource consumption, economic benefits and carbon emissions, the total allocation of water resources and the total allocated area of crop planting after optimization were 118.678 × 108m3 and 4598.796 × 103ha, respectively, decreases of 22.87% and 7.9%. The planting structure changed. The area planted with rice increased by 4.25%, the area planted with corn decreased by 15.5%, and the area planted with rapeseed decreased by 14.96%. Electricity, fertilizer and straw burning contributed significantly to agricultural carbon emissions, with average contributions of 68.0%, 15.9% and 6.6%, respectively. The multiobjective optimization model established in this paper can improve resource utilization and reduce the environmental impact of agriculture, which are of great significance in terms of achieving the goal of "carbon neutrality" and promoting the sustainable development of regional agriculture. The established model framework can be applied to regions with limited resources around the world. [ABSTRACT FROM AUTHOR]

Despite the considerable contribution of hydropower for meeting electricity demand and meanwhile achieving free carbon emission, the rationality of hydropower exploitation needs to be reassessed in the context of hydropower curtailment being severe in some hydro-dominant areas. In this paper, a two-stage fuzzy-stochastic chance-constrained interval (TFCI) regional energy system optimization model under multiple complexities is developed for systematically assessing the rationality of existing hydropower exploitation plan, and reflecting the tradeoff between system cost and reliability for Sichuan territory where the exploitable hydropower resources rank first in China. Results showed that the degree of hydropower overcapacity would become far more severe under the real existing energy structure planning. Instead of continuously boosting hydropower exploitation, proper limitation on hydropower installed capacity expansion to make other renewable energy obtain deserved promotion can effectively reduce system cost and improve the utilization efficiency of all the renewable technologies. The highest utilization efficiency of hydropower, wind power and solar power could achieve [90%, 100%], [100%, 100%], and [100%, 100%], respectively. The obtained results also indicated that greater uncertainty about system cost may have to be faced if policymakers aim to lower risk and enhance system reliability. Suggestions are provided for eliminating the irrationality of hydropower in Sichuan and other similar hydro-dominant regions based on above mentioned conclusions. • Developing a TFCI model for the rationality of renewable energy development. • Evaluating Sichuan's hydropower exploitation from a comprehensive view. • Investigating far more severe hydropower curtailment under existing energy policy. • Suggesting proper limitation on hydropower exploitation. [ABSTRACT FROM AUTHOR]

• A spatial random forest-based downscaling and merging method (SRF-DM) is proposed. • SRF-DM performs better than the original satellite-based precipitation products. • SRF-DM is more accurate than the classical machine learning-based methods. • Spatial autocorrelation is the most important variable. • SRF-DM has a good performance even when the gauge density is low. Publicly available satellite precipitation products (SPPs) are essential inputs for hydrological models. However, the existing SPPs suffer from coarse resolutions and large uncertainties, which greatly hinder their widespread applications. Thus, to fully utilize the unique characteristics of each individual SPP, a spatial random forest (SRF)-based downscaling and merging (SRF-DM) method is proposed to fuse multiple SPPs and gauge observations in this paper. The proposed method incorporates spatial autocorrelation information between precipitation observations through a covariate. This covariate is estimated using ordinary kriging interpolation on spatial neighbors that have a high correlation with the target location. The proposed method was used to generate 1-km daily precipitation data using the datasets from five satellite precipitation products (IMERG, GSMaP, CHIRPS, MORPH, and PERSIANN) and gauge observations in the period from January 1, 2015 to December 31, 2019 over Sichuan province, China. The performance of SRF-DM was compared with the original SPPs, XGBoost-based downscaling and merging (XGB-DM), two double-layer machine learning (ML) methods, namely RF-RF and RF-artificial neural network (RF-ANN), and three single ML methods, namely RF, ANN, and RF-based Merging Procedure (RF-MEP). The experimental results demonstrate the following findings: (i) SRF-DM is more accurate than the original SPPs across different temporal scales (i.e., daily, monthly, and seasonal) in terms of statistical and categorical accuracy measures, (ii) SRF-DM outperforms the six ML-based methods in estimating high precipitation and capturing spatial precipitation patterns, (iii) the spatial autocorrelation between neighboring precipitation data is the most significant factor in both downscaling and merging, and (iv) the performance of SRF-DM is influenced by gauge density, but it still yields good results even with a limited number of gauges. On the whole, SRF-DM is considered an effective tool for generating daily precipitation products with high accuracy and resolution, which is primarily attributed to its satisfactory performance in regions with diverse precipitation patterns and topography. [ABSTRACT FROM AUTHOR]

With the completion of the poverty alleviation task in China, the Chinese economy has made great breakthroughs. Meanwhile, the implementation of Chinese "dual carbon" goal has entered an important window period of both strategic opportunities and difficulties. The emission of carbon dioxide (CO2) leads to the greenhouse effect, which affects the sustainable development of society. Therefore, this paper proposes an improved analytic hierarchy process (AHP) with Slacks-based measure integrating data envelopment analysis (SBMDEA) (AHP-SBMDEA) based efficiency evaluation model for different provincial-level administrative regions in China, which is used to analyze and optimize the Chinese energy structure of different provincial-level administrative regions. With coal, gasoline, petroleum, fuel oil, diesel, crude oil and natural gas as inputs, the per capita Gross Domestic Product (GDP) as the desired output and the CO2 as the undesired output, after linear weighted calculation of the results of the AHP-SP model and the SBMDEA model, the energy efficiency evaluation model of different provincial administrative regions in China is established. The results show that there is a large difference in efficiency between Chinese northern and southern regions, and the overall efficiency of southern regions is higher than that of northern regions. In addition, it is easier to find out the optimal energy efficiency benchmark, which can provide suggestions and help to guide the energy consumption input structure improvement of other inefficient provincial-level administrative regions. Furthermore, the energy structure can also be adjusted through the redundant variable calculated by the SBMDEA model. For example, Sichuan Province can reduce the consumption of the coal, the gasoline, the diesel, the fuel oil, the crude oil and the natural gas by 5269.95 × 10000 tons (WT), 513.01 WT, 59.05 WT, 34.37 WT, 4,73.33 WT and 130.37 billion cubic meters (BCM), respectively. Its CO2 emissions can be reduced by 1925.4 WT, and raise the efficiency of energy utilization in the province. [Display omitted] • Novel economy and CO 2 emissions evolution model based on a AHP-SBMDEA is proposed. • The proposed model can identify the optimal energy efficiency benchmark. • GDP per capita can be increased and CO 2 emissions can be decreased. [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]

• The paper quantitatively summarizes the distribution and development of pumping distress using various field and laboratory methods. • The paper adopts GPR techniques to assess the structure of asphalt pavements. • The paper identifies potential causes of the pumping phenomenon. • The paper quantifies the extent and severity of the pumping distress. Pumping distress refers to the phenomenon of dynamic water entering a pavement, soaking the cement concrete layer to form slurry, and being pumped out of the pavement void under the action of traffic loading. Pumping distress is frequently reported in high temperature and rainy regions, such as Sichuan province in China. Various factors contribute to pumping distress on bridge decks, but most of these factors have merely been subjected to qualitative assessment. The aim of the study is to conduct a comprehensive quantitative analysis through three years of field investigations and laboratory experiments. The field investigations include ground penetrating radar (GPR), pavement permeability tests, skid resistance tests, and drainage facilities surveys. The quantitative analysis of the field and laboratory inspections revealed that the formation reason, deterioration rate, and damage degree of pumping distress were different between the truck and emergency lanes. The occurrence of pumping distresses was significantly related to the uneven construction of the bridge deck leveling layer, compaction segregation, and poor drainage. Additionally, the influence of pavement thickness uniformity on pumping distress was evaluated by incorporating GPR techniques. Failure in the waterproof adhesion layer resulted in the barrier between the cement concrete deck and the asphalt mixture breaking, which allowed alkaline sources to move and transfer to the pavement layer easily. The outcomes of this study can help bridge authorities and construction contractors choose appropriate design and construction measures to prevent pumping distress. [ABSTRACT FROM AUTHOR]

The Xigeda formation, widely distributed in southwestern China, is a special semi-diagenetic rock with horizontal bedding，which is mudding in water. In order to study the failure law, catastrophe characteristics and catastrophe mechanism of the interbed type to the surrounding rock and structure of Xigeda formation tunnel, this paper, by means of field investigation, indoor test, numerical simulation, field monitoring and theoretical research, relying on more than ten Xigeda formation tunnels in the Chengdu-Kunming double track railway, analyzes the apparent failure characteristics and catastrophe mechanism of the surrounding rock of Xigeda formation tunnels with different interbed types. The results show that: the catastrophe characteristics of Xigeda formation tunnel have certain water content sensitive area and influence area division of interbed type. The water content of Xigeda formation is 25% - 30% of the catastrophic critical region of Xigeda formation tunnel. In this critical region, the vault of the overlying Xigeda formation tunnel is prone to large deformation, the invert of the underlying Xigeda formation tunnel is prone to large uplift deformation, and the side wall and tunnel face of interlayer Xigeda formation tunnel are prone to large extrusion deformation; when the water content of Xigeda formation is 30%, it becomes a weak layer, and under the effect of interbed, the rock and soil of Xigeda formation are prone to large deformation, resulting in catastrophes by extruding the tunnel structure; based on the analysis of chemical effect, physical effect and mechanical effect, the structural components of interbed rock chemically react with water, leading to weakening of the strength and causing catastrophic effects. The catastrophic effect is similar to that of simply supported beam in the strong and weak regions of the interbed, while the weakening effect of the interlayer structural plane leads to the opening of the interlayer fracture plane of the tunnel surrounding rock and the large interlayer dislocation displacement, which forces the shear failure of the supporting structure. The research results of this paper can provide theoretical guidance for the Sichuan-Tibet railway to be constructed. • The research object is Xigeda stratum which is sensitive to water. • Reveal the disaster modes of Xigeda stratum tunnels with different interbed types. • Investigate the catastrophic mechanism of Xigeda stratum tunnel under interbed effect. • Obtain the catastrophic critical water content of Xigeda stratum tunnel. • Provide theoretical basis for Xigeda stratum tunnel construction. [ABSTRACT FROM AUTHOR]

Binding material is a key component of painted cultural relics, and research on binding agents ("binders") is of great significance for the study of the history and preservation of cultural artefacts. In this work, our team collected 129 painted samples from 28 ancient cultural relics located in 9 provinces of China. We used an enzyme-linked immunosorbent assay (ELISA) as well as immunofluorescence microscopy (IFM) to identify proteinous binders in these samples. Our results show that 51 painted samples were found to contain animal glue, 13 samples were found to contain egg ovalbumin, and 2 samples were found to contain casein. Two mural painting samples prepared in the Ming and Qing Dynasties (14–20 century AD) from the Jiazaerjia Mountain Grottoes in Sichuan province were found to contain casein, and this is the first time that casein binders were found in Chinese painted cultural relics. On top of our detection results, this paper also reports statistics on the chronology, geographical distribution, and artwork types in which organic binders are found, and provides evidence of the use of proteinous binders in Chinese painted cultural relics. [ABSTRACT FROM AUTHOR]

The Large High Altitude Air Shower Observatory (LHAASO) is located in Daocheng, Sichuan. Featured with frequent thunderstorms in summer seasons, it is beneficial to study the influence of atmospheric electric field on cosmic rays during thunderstorms. In this paper, Monte-Carlo simulations are performed to study the effect of thunderstorm electric field on the cosmic ray secondary electron energy at LHAASO. The energy distribution of electrons changes under the action of electric field. In the low energy region, the total number of electrons increases significantly, while at high energies, it does not change obviously. In the electric field of 1700 V · cm − 1 (above the critical field of the Relativistic Runaway Electron Avalanche (RREA) process), the electrons with an energy less than 120 MeV can be accelerated. When the energy is below 60 MeV, the number of electrons increases exponentially with an amplitude up to about 2252%. It is consistent with the theory of RREA. When the electric field strength is 1000 V · cm − 1 (below the threshold of the RREA process), the electrons with an energy less than 70 MeV are accelerated, and their number increases significantly, but the increase (about 86%) is far lower than that of the critical field of the RREA process. The physical mechanism for accelerating the cosmic ray secondary particles by the thunderstorm electric field is discussed in the case when the electric field is less than the runaway electric field. These results may provide important information for studying the variations of cosmic ray intensity on the LHAASO detection surface during thunderstorms. [ABSTRACT FROM AUTHOR]

Evaluating reservoir storage and percolation capacities, which are closely associated with pore morphology and connectivity, is significant for the exploration and exploitation of oil and gas fields. However, ultradeep carbonate gas reservoirs have extremely high heterogeneity and complexity compared to other relatively shallow reservoirs. Therefore, investigations into all aspects of ultradeep carbonate face enormous challenges. To the best of our knowledge, no systematic study on the pore structure characteristics of ultradeep carbonate gas reservoirs has been conducted to date. In this paper, the pore structure characteristics and their effects on the gas storage and percolation capacities of the Deng IV Member gas reservoir were investigated using conventional petrophysical measurements, casting thin section analysis, scanning electron microscopy (SEM), high pressure mercury intrusion (HPMI) tests, and multiscale CT scanning analysis. The results show that the lithology of the Deng IV Member reservoir is dominated by algal clotted dolomite, algal stromatolite dolomite and algal doloarenite. The conventional petrophysical measurements indicate that the average porosity and permeability are 3.91% and 1.02 mD, respectively. However, the high porosity (8-4%) and high permeability (10–10,000 mD) intervals are developed locally. The casting thin sections, SEM and two-dimensional CT analyses identify six main types of reservoir spaces in the Deng IV Member: interparticle dissolution pores, intercrystal dissolution pores, fenestriform cavities, dissolution cavities, structural fractures and dissolution fractures. Furthermore, three types of throats, that is, necking, tubular and lamellar, were also detected. Four types of reservoirs, namely, matrix type, pore type, cavity type and fracture-cavity type, were classified according to the comprehensive analysis of HPMI data and curves. Three-dimensional pore throat network topologies were reconstructed for four types of representative core samples based on the multiscale CT scanning data and "maximum-ball" method. The distribution characteristics of pore throat radii, volumes and coordination numbers reveal the following: the reservoir space of fracture-cavity type is dominated by cavities and multiscale pore throats with the best pore-throat connectivity; the reservoir space of cavity type is primarily controlled by cavities and large-scale pore throats with moderate connectivity; the reservoir space of pore type comprises multiscale pore throats with moderate connectivity; and most areas of matrix type reservoir are occupied by rock matrix, and the pore-throat connectivity is the worst. In conclusion, the development of fractures and bedding cavities considerably improves the reservoir percolation capacity, and the development of cavities is an important supplement to the reservoir storage capacity. The reasonable combination of cavities and fractures is the basis for the efficient development of ultradeep carbonate gas reservoirs. • A variety of techniques and methods were used to characterize pore structures of a ultradeep carbonate gas reservoir. • Storage and percolation capacities of a ultradeep carbonate gas reservoir were comprehensively analyzed. • Four types of reservoirs were classified and evaluated according to the results of HPMI and multiscale CT scanning. • Reasonable combination of cavities and fractures is the key to the efficient development of ultradeep carbonate reservoirs. [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]

Onsite Earthquake Early Warning (EEW) applications require robust predictive models that can relate the early part of the recorded seismic waves to seismicity and/or ground shaking characteristics, the latter representing the variables used to make decisions about raising or not an alarm. The use of limited information to establish these models within a real-time estimation setting, typically corresponding to the first few seconds after the identification of the seismic wave arrival, introduces significant uncertainty (variability) in the predictions. To increase the number of historical observations available for the model calibration, data from multiple seismic stations within the same geographic region are utilized for the latter task. Unfortunately, this introduces additional sources of variability in the predictive model development, originating from local geographical effects and site conditions that affect differently the underlying physics at each station. This paper introduces a hierarchical Bayesian model updating framework to address this challenge. To better focus the research effort, the calibration of earthquake magnitude nonlinear regression models based on the seismic maximum predominant period is investigated, though underlying principles can be extended to other type of decision variables and intensity measures used in EEW applications. Within the hierarchical updating framework, the predictive models for each station are separately calibrated (first level), while sharing information across the stations by selecting common calibration hyper-parameters (second level). This facilitates a reduction of the variability of the estimates originating from regional wave propagation effects while simultaneously providing sufficient amount of data for calibrating the predictive models even for stations with scarce available records. To support computational efficiency in the hierarchical calibration, conjugate priors are utilized, while for accommodating nonlinear regression relationships samples from the posterior distribution, representing the model calibration, are obtained using Metropolis-within-Gibbs sampling. As illustrative case study, the application to the Sichuan region of Southwestern China is examined, with extensive comparisons performed for the accuracy and robustness of the resultant probabilistic predictive models. • Moment magnitude nonlinear models for onsite early warning applications are calibrated. • The predictive models for each station are separately calibrated. • Information sharing across the stations is established within a hierarchical Bayesian updating scheme. • This allows reduction of the variability of the estimates originating from regional wave propagation effects. • Computational efficient implementation relies on conjugate priors and Metropolis-within-Gibbs sampling. [ABSTRACT FROM AUTHOR]

The Wide Field of view Cherenkov Telescope Array (WFCTA) of the Large High Altitude Air Shower Observatory (LHAASO), located in Haizishan National Natural Reserve, Sichuan Province, China, is designed to perform nearly calorimetric measurements of extensive air showers induced by cosmic rays with energies between 10 13 eV –10 18 eV. The end-to-end calibration method will be employed in the WFCTA and nitrogen lasers have been proven to work properly in our application at the altitude of 4410 m a.s.l. for the first time. Due to extremely harsh environment, especially outdoor temperature as low as about −30 ° C during operation of WFCTA, a high-stability thermotank for lasers was designed to stabilize temperature and humidity, with a thermal stability of 1 ° C. In order to precisely control the beam pointing, a high-precision 3D Lifting Rotating Platform (HiRoP) with a home-made standard zero monitoring system is developed. To eliminate the error of the beam pointing by manual controls, an automatic scanning program was adopted to control the beam pointing when scanning the full field-of-view (FOV) of WFCTA. Both the on-site and remote controls are applied for the nitrogen laser systems and ∼ 13 million laser shots have been recorded by WFCTA from Sept. 2020 to May 2022. In this paper, the design, properties, operation and the on-site performance of the nitrogen laser systems at LHAASO are reported. [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 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]

Due to the instability of extracting elastic parameters from conventional elastic impedance variation with incident angle (EVA) pre-stack inversion and the fact that single-trace inversion does not consider the correlation between seismic traces and the lateral continuity of inversion results. An anisotropic total variation multitrace inversion method based on the L P norm constraint is proposed on the basis of EVA inversion. In this paper, the L P norm is used as the regularization constraint, the longitudinal and transverse difference operators are introduced, and the alternating direction multiplier algorithm and the 2D Sylvester equation solver algorithm are used as inversion algorithms to achieve a multitrace inversion of the elastic parameters. The feasibility of the method proposed in this paper is verified by making full use of the advantages of both methods and conducting trial calculations on some blocks of the Marmousi2 model. The method was further validated by applying it to actual data from marine shales of the Longmaxi-Wufeng Formation in the southern Sichuan Basin. The inversion results were validated using a combination of brittleness indices and microseismic monitoring to confirm the feasibility of the method in this paper. •Proposed anisotropic total variation multitrace inversion method based on Lp norm. •Multitrace inversions enhance the lateral continuity of inversion results. •Different noise tests demonstrate the noise immunity of the inversion method. •Validation of the method with brittleness index and microseismic events. [ABSTRACT FROM AUTHOR]

Due to the instability of extracting elastic parameters from conventional elastic impedance variation with incident angle (EVA) pre-stack inversion and the fact that single-trace inversion does not consider the correlation between seismic traces and the lateral continuity of inversion results. An anisotropic total variation multitrace inversion method based on the L P norm constraint is proposed on the basis of EVA inversion. In this paper, the L P norm is used as the regularization constraint, the longitudinal and transverse difference operators are introduced, and the alternating direction multiplier algorithm and the 2D Sylvester equation solver algorithm are used as inversion algorithms to achieve a multitrace inversion of the elastic parameters. The feasibility of the method proposed in this paper is verified by making full use of the advantages of both methods and conducting trial calculations on some blocks of the Marmousi2 model. The method was further validated by applying it to actual data from marine shales of the Longmaxi-Wufeng Formation in the southern Sichuan Basin. The inversion results were validated using a combination of brittleness indices and microseismic monitoring to confirm the feasibility of the method in this paper. •Proposed anisotropic total variation multitrace inversion method based on Lp norm. •Multitrace inversions enhance the lateral continuity of inversion results. •Different noise tests demonstrate the noise immunity of the inversion method. •Validation of the method with brittleness index and microseismic events. [ABSTRACT FROM AUTHOR]

Gravitational anomalies play a significant role in qualitative and quantitative interpretations of structural settings. Vertical derivative, horizontal derivative and their combinations of gravity anomaly are popularly utilized for edge detection and depth estimations. However, the results are usually deviated from the actual location even for vertical-sided geological sources, especially in the case of deeper ones. The tilt angle (TA) and normalized tilt angle (TDX) as well as their Euler deconvolution have been proved to be more effective than the traditional methods to calculate the horizontal position and depth of sources, yet there are unstable results from the Tilt_Euler and TDX_Euler techniques. This is mainly because the derivatives of the TA and TDX are not calculable while the horizontal derivatives of gravitational anomalies approach to zero. This paper propose an extended tilt angle (ETA) and its Euler deconvolution (ETA_Euler) that guarantees the stability of the results. Results from theoretical models with noise-free and noise-corrupted gravity anomalies indicate that the solutions obtained from the proposed methods approximate to the actual parameters. We compare our proposed method to traditional methods, and the results demonstrate that solutions from ETA_Euler deconvolution are more accurate and concentrated when delineating gravity–anomalous locations and depth. However, the results of the ETA_Euler are sensitive to noise due to the calculation of second-order derivative. Our methods employ upward continuation to an appropriate height to reduce the influence of noise. This paper utilized the above methods to gravity data from the Longmenshan thrust belt (province of Sichuan, China) and adjacent areas. The results indicate that faults within the Longmenshan thrust belt and adjacent areas mainly extend northeast and northwest, correlating well those inferred from other geological and geophysical methods. • An extended tilt angle (ETA) and its Euler deconvolution (ETA_Euler) were proposed. • The applicability of ETA_Euler method was discussed. • The ETA_Euler solutions under peak constraints are more accurate and concentrated. • The application of this method to gravity data in Longmenshan was studied. • The ETA_Euler method has an advantage in detecting shallow geological bodies. [ABSTRACT FROM AUTHOR]

• CH 4 and (sub and supercritical) CO 2 adsorption experiments on shales were performed. • The adsorption ratio of CO 2 over CH 4 for tested shale samples ranges from 1.66–8.32. • Langmuir, D-A, D-R and Ono-Kondo models were fitted to the adsorption data. • The favorable models used to fit CH 4 and CO 2 adsorption on shales are recommended. A thorough study of the adsorption behavior of shales to methane (CH 4) and carbon dioxide (CO 2) is critical for carbon dioxide sequestration in shale gas reservoirs and enhanced shale gas recovery. This paper discusses the results of an adsorption study of CH 4 and CO 2 , in single gas environment, on a set of shale samples taken from the Sichuan and Ordos Basins. The results indicated that shale exhibit higher affinity to CO 2 as compared to CH 4 under similar pressure and temperature conditions, and the preferential adsorption ratio of CO 2 over CH 4 varies between 1.66 and 8.32. Furthermore, the experimental data were modeled using Langmuir, Dubibin-Astakhov (D-A), Dubinin-Redushckevich (D-R) and Ono-Kondo models. The accuracy of the models in quantifying CH 4 and CO 2 adsorption on shale was compared using an error analysis technique. For CH 4 , both of Langmuir and D-A models performed satisfactorily with comparable accuracy. For subcritical CO 2 , the performance of the D-A model is the best. However, for supercritical CO 2 , Ono-Kondo model fitted the experimental data the best, which is the proposed model to use. The results of this study can provide the basis for the estimation of the CO 2 sequestration capacity in shale formations. [ABSTRACT FROM AUTHOR]

The main target for hydrocarbon exploration of terrestrial strata in Sichuan Basin is the tight gas sandstone reservoir of the Upper Triassic Xujiahe Formation. Xujiahe Formation in YB area is a major discovery of hydrocarbon exploration in recent years, which is characterized as tight with ultralow porosity, ultralow permeability, and intensive heterogeneity. The tectonic fractures have important influence on accumulation and productivity of gas in the area. In the paper, analysis data of outcrop, core, imaging logging and other experiments were used to determine the characteristics, formation periods and genetic mechanisms of tectonic fractures. There are mainly high-angle and low-angle shear fractures in the area, which caused by tectonic stress. The length of the fractures is mainly 0–4 m from the outcrop and 10–20 cm from the cores and fracture frequencies (number per meter) is mostly 2-7 m−1, 2-4 m−1 respectively. The fracture fillings are mainly calcite, argillaceous and carbonaceous, about 60% of the fractures is unfilled or incompletely filled. Without considering the diagenetic fractures, there are three periods of the fractures: the middle-late Yanshanian tectonic movement, the early-middle Himalaya tectonic movement and the late Himalaya tectonic movement. The first period of the fractures are mainly filled with fine calcite, homogenization temperature of inclusion is 75–85 °C and the maximum effective principal stress of paleostress is 71.64 Mpa. The second period of the fractures are half-filled (or unfilled) with coarse calcite, homogenization temperature of inclusion is 150–175 °C and the maximum effective principal stress of paleostress is 74.91 Mpa. The third period of the fractures are low filling degree and cuts formed fractures clearly, the maximum effective principal stress of paleostress is 86.52 Mpa. For these tectonic movement, there are four sets of the plane "X" shear fractures in the area: NE strike fractures, NW strike fractures, NEE strike fractures, S N strike fractures. There are one set of the profile shear fractures of NWW strike. Finally, the complex fault system of nearly N S, NW and NE strike are formed in YB area. • A new method for comprehensive study of the fracture formation period is provided. • The main fracture formation dating of Xujiahe Formation in YB area as follows: 36–176 Ma and 0.2–36.4 Ma. • There are 3 periods tectonic fractures of Xujiahe Formation and formation period of different fracture types is identified. [ABSTRACT FROM AUTHOR]

• Resource-Richness Analogy Approach used in less explored reservoirs is proposed. • Genesis-Statistics Assessment Approach for heterogeneous tight oil is proposed. • The parameter criteria of lacustrine tight oil resource assessment are established. • In-place tight oil resources in China's major basins are estimated of 12.6 × 109 t. • 15 most favorable plays are outlined with in-place resources of 5.3 × 109 t. Large-scale commercial development of shale gas and tight oil resources in North American and continuous discoveries of tight oil in China lead to the recognition of the importance of assessment on tight oil resources. Based on the characteristics of China's tight oil reservoirs and exploration status, this paper discusses a workflow focusing on in-place resource evaluation. In the workflow, a Resource-Richness Analogy Approach (RR-AA) is proposed for assessment of tight oil resources in less explored areas, a Genesis-Statistics Assessment Approach (GS-AA) for lacustrine tight oil resources with strong heterogeneity and regions where more delicate assessment is required, and an EUR Analogy Approach (EUR-AA) for assessment on recoverable tight oil by fully using available EUR data of production wells. After analyzing the geological characteristics of the formation of tight oil in the Ordos, Bohai Bay, Songliao, Junggar, Sichuan and other major Basins, the distributions of essential parameters such as reservoir thickness, area and porosity have been defined, and the parameter evaluation criteria have been established. Finally, the tight oil resource potentials in the major basins in China have been evaluated using one of the three methods and the prospective areas of high resource abundance are outlined in each of basins. The results from this study show that China's tight oil resources have a large potential and good exploration future. The estimated in-place tight oil resources are 12.580 × 109 tons, mainly distributed in the Ordos, Songliao, Bohai Bay and Junggar Basins. 15 most favorable zones are proposed having in-place resources of 5.296 × 109 tons. [ABSTRACT FROM AUTHOR]

• Zircon fission track analyses of the pre-Cretaceous sandstones are reported. • ZFT data constrain the low-temperature evolution or sediment provenance. • The westward decreasing trend in age represents a Mesozoic intracontinental orogeny. • Sediments source from the Qinling orogen due to its multistage evolution. The Xuefeng Intracontinental Tectonic System (XITS) is a large-scale compressional tectonic system in the central South China block. It is characterized by northeast-trending fold-thrust belts involving the Xuefeng zone, the Chevron syncline fold-thrust zone, the Chevron anticline fold-thrust zone and the Central Sichuan basin. This paper reports detrital zircon fission track (ZFT) analyses of the sandstones sampled from Neoproterozoic to Middle Jurassic sequences, and further discusses their relation with low-temperature tectonic evolution and sediment provenance. The totally annealed ZFT data of 452–377 Ma from the Neoproterozoic and Devonian sandstones were related to an Early Paleozoic low-temperature exhumation of the Jiangnan orogen due to intracontinental orogeny in the South China block. Those annealed ZFT components from Triassic to Jurassic sandstones, grouped 236–189 Ma, 189–142 Ma, and 142–124 Ma decreasingly from east to west structurally imply a northwestward progressively squeezing by the Xuefeng intracontinental orogeny as a result of the Paleo-Pacific subduction. The unannealed age components (411 Ma, 362–377 Ma, 270–216 Ma, and 209–183 Ma) of the Upper Triassic to Middle Jurassic sandstones, are comparable to the multistage tectonic evolution of the Qinling orogen through subduction, accretion and collision and are therefore indicative of sample potential provenance. [ABSTRACT FROM AUTHOR]

Nucleic acid constituents are the main functional ingredients in edible fungi, therefore understanding the nucleic acid constituents of edible fungi often eaten on the table by the Chinese people is of significant value. In this study, Sichuan Provincial Center for Disease Control and Prevention collected 147 samples of edible fungi (including certain species that the Chinese often eat) from different parts of the Sichuan Basin. A new UPLC-QqQ/MS method has been developed to determine the 17 nucleic acid constituents in these 147 samples, including guanosine, adenosine, uridine, cytidine, inosine, thymidine, xanthosine dehydrate, 2′-deoxyguanosine, 2′-deoxyadenosine, 2′-deoxyuridine, 2′-deoxycytidine, 2′-deoxyinosine, guanosine 5′-monophosphate, adenosine 5′-monophosphate, uridine 5′-monophosphate, cytidine 5′-monophosphate, and inosine 5′-monophosphate. Finally, similarity assessment of the main edible fungus was performed using vectorial angle cosine method, and hierarchical cluster analysis was used to classify all the 147 samples. The results showed that some edible fungi have high similarities, especially in Lentinula edodes (Berk.) Pegler, the monogenic nucleotides content of which (55.84 ± 8.4 mg/100 g) is far greater than any other edible fungus, which is directly related to its taste. For quality control, this paper proposed to use the reference values of total nucleic acid compounds in edible fungi computed by percentile threshold method. This is the first time a comprehensive evaluation of nucleic acid constituents of different edible fungi of daily consumption was conducted for a large region, and the results is conducive to the quality evaluation and quality control of edible fungus. Unlabelled Image • Developed a new UPLC-/MS method for the determination of 17 nucleic acid constituents • The similarity was assessed by vectorial angle cosine and hierarchical cluster analysis. • The reference values of total nucleic acids in each species computed by percentile threshold method. • Can be applied for quality evaluation and quality control of edible fungus [ABSTRACT FROM AUTHOR]

Abstract Multiphase (adsorbed and free) liquid water that is accumulated in shale matrix pores (i.e., pore water) substantially affects the storage and transport of gas in shale. Traditionally used macroscopic parameters (e.g., initial, irreducible, mobile and clay bound water saturations) are not sufficient to describe the microdistribution characteristics and mobility of pore water in the complex porous shale matrix. In this paper, a new classification was proposed in which the pore water is composed of adsorbed and free parts, of which the latter is subdivided into capillary bound and mobile water. The components of pore water have the following features: during the centrifugation process, (a) adsorbed water is essentially immobile, while free water is potentially mobile; (b) capillary bound water is gradually transformed into mobile water with increased centrifugal pressure difference; and (c) the maximum mobile water amount is numerically equal to the free water amount. Based on the classification, an effective technique, which integrates centrifugation, water imbibition and low temperature nitrogen adsorption methods with the modified Li's adsorption ratio equation (2018), was established to quantitatively evaluate the microdistribution characteristics (adsorbed and free amounts and their ratios) and the mobility (mobile amount, potential and capacity) of pore water in marine shales from the southern Sichuan basin in China. Furthermore, the mechanism of controlling the microdistribution and mobility of pore water is analyzed with respect to the microscopic pore structure characteristics and material compositions of shales. The primary results demonstrate that (1) adsorbed and free water amounts obtained by centrifugation tests range from 5.145 to 31.282 mg/g (adsorbed) and from 7.880 to 49.751 mg/g (free); the weight ratio of adsorbed water is 0.268–0.629. (2) The mobile potential and mobile capacity of pore water are represented by the free water amount and mid-value pressure difference, respectively. A positive relationship between these two parameters occurs in the studied shales. (3) Pore microstructure characteristics of shale mainly impact the microdistribution and mobility of pore water in the shale matrix. The adsorbed water amount is closely associated with the specific surface area of pores, while the free and mobile water amounts are controlled by the pore volume. The ratios of adsorbed and free water depend on the size and morphology of pores for certain state parameters. The mobile ratio is impacted by pore complexity, which indicates that as the complexity increases, the mobile ratio decreases. The study provides significant insight into the microdistribution and mobility of pore water in gas shale matrix. Highlights • A new classification was proposed for the components of pore water. • A technique was established to evaluate the microdistribution characteristics and the mobility of pore water in shales. • Mechanism of controlling the microdistribution and mobility of pore water was analyzed. [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]

• Abrupt high δ13C -CO2-DIC in the hot springs occurred before earthquakes. • The carbon isotopic spikes are caused by fractionation due to tectonic activity. • The δ13C -CO2-DIC of hot springs changed markedly before and after the earthquakes. • The elevated carbon isotopic levels may be a signal for the subsequent earthquakes. Geothermal springs are controlled by deep faults, which are the major causes of earthquakes. A series of geochemical indicators of hot springs, such as carbon dioxide content (CO 2), carbon isotope and noble gas isotope etc., have been used for earthquake monitoring and early warning at home and abroad. Given that previous studies have failed to establish an inevitable link between the carbon isotopic variations of hot springs and seismic activities, in this study, mass spectrometry techniques were used to analyze the carbon isotopes of gaseous CO 2 and noble gas isotope in hot springs, thermal water, and newly formed travertines from western Sichuan before and after an Ms 4.8 earthquake (i.e., 7.14 earthquake). The results showed that the carbon isotope level of the hot spring system increased significantly before the earthquake, i.e., δ13C CO2 = -2‰ to 3.3‰, δ13C DIC = 2.2‰ to 6.6‰ (DIC = dissolved inorganic carbon in geothermal water), R/R A = 0.90–1.83, and δ13C travertine = 1.76‰ to 5.75‰. These indicators decreased markedly 1 week after the earthquake, whereas the helium isotope ratio of R/R A did not exhibit a noticeable change (δ13C CO2 = -3.9‰ to 0.4‰, δ13C DIC = 1.6‰ to 4.1‰, R/R A = 0.68–1.87). Combined with previous thermodynamic calculation and experimental results on carbon isotope fractionation of the CO 2 –calcium carbonate system, we suggest that the high carbon isotope characteristics of hot springs are caused by carbon isotope fractionation following the release of CO 2 from fault carbonate decomposition owing to tectonic activity, not by a mixture of different carbon sources. A high carbon isotopic delivery path in geothermal water, from released CO 2 to DIC and then to travertine, was observed. The new mechanism proposed in this paper reveals the intrinsic relations between the changes of the hot spring geochemical properties and deep tectonic activities, and the variations of these geochemical parameters before and after earthquakes may assist in capturing seismic precursors. A post-peak earthquake warning model has thus been preliminarily proposed, however, long-term monitoring data are required to reduce some uncertainties. [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]

The sealing capacities of shale, roof, and floor strata are essential for the preservation of shale gas. Sealing capacity development and its influence on shale gas composition and organic matter pore development are important but have not been addressed by existing studies. In this paper, the Upper Ordovician Wufeng-the first member of the Lower Silurian Longmaxi Fm. in the Yangtze region is selected as the study object. We dissected the J1 well in the Jiaoshiba block inside the Sichuan Basin and the Y6 well in the Youyang block outside the Sichuan Basin to analyze the gas components and carbon isotopes in recovered shale gas. In this study, two microscope techniques (i.e., FIB-SEM and FIB-HIM), porosity measurement, TOC content analysis, permeability tests, isothermal adsorption measurements, are utilized. The analytical results show that both the roof and floor strata have vertical sealing effects on the organic-rich shale due to their different physical properties compared to the shale. The shale overburden pressure increases with burial depth, and the adsorbed gas increases with increasing TOC content and thickness: all of these can lead to a decrease in permeability and an increase in self-sealing capacity. This paper determined the formation mechanism of the sealing capacity for shale, roof and floor strata. Furthermore, the control patterns of "sealing capacity strength" on the shale gas source and organic matter pore development are clarified. The main findings are as follows: when the shale, roof, and floor strata have a strong sealing capacity, only a small amount of liquid hydrocarbons can be discharged from the shale, but the natural gas formed due to liquid hydrocarbon cracking is abundant. Under such circumstances, shale gas has a mixed origin of liquid hydrocarbon cracked gas and kerogen cracked gas; the carbon isotopes are inverted; abundant pyrobitumen pores with high porosity and good connectivity are developed. When the sealing capacities are weak, the amount of liquid hydrocarbons discharged from the shale are high, and the amount of natural gas is low. The shale gas is mainly derived from kerogen cracking with weak or no carbon isotope inversion, and kerogen pores are small with poor connectivity. These findings will advance the study of shale gas formation mechanisms and provide a scientific basis for selecting shale gas exploration area. • Due to different physical properties, the roof and floor strata provide a seal for the organic-rich shale. • As the burial depth, TOC content, and the shale thickness increase, the shale has a stronger sealing capacity. • Sealing capacity plays an important role in the characteristics of shale gas and organic matter pore development. [ABSTRACT FROM AUTHOR]