Southwest Mountainous Area Research Articles

Influencing Factors of Residents’ Perception of Responsibilities for Heritage Conservation in World Heritage Buffer Zone: A Case Study of Libo Karst

Local residents of buffer zones, as a key factor in the World Heritage conservation and sustainable development, have not received sufficient attention in most developing countries, especially in the mountainous areas where poor and backward ethnic minorities live. To fill this research gap, this paper takes the Karst World Heritage buffer zone in Libo, Guizhou Province, southwest mountainous area of China, as the research area, and explores the factors that influence the perception of residents’ responsibility for the World Heritage conservation by taking local residents who are involved in tourism management as the research subjects. Data were collected in the buffer zone of the Libo World Heritage site and 186 valid data were generated. SPSS 25.0 and AMOS 27.0 software were used to analyze the questionnaire data and construct a structural equation model. The results showed that environmental protection behavior had the greatest impact on residents’ perception of responsibility for heritage conservation (0.93), followed by the recognition of heritage value (0.55), tourism positive impact (0.39), and place identification (0.34), among which the positive impact of tourism had a greater impact on the perception of heritage value (0.52). The results of the study emphasize the importance of the recognition of heritage value and positive tourism influence on the formation of residents’ perception of responsibility for heritage conservation, and provide an empirical basis for the conservation of the World Natural Heritage.

Large-Scale Field Test Study on Failure Mechanism of Non-Cohesive Landslide Dam by Overtopping

In recent years, landslide lake disasters occur frequently in southwest mountainous areas of China. Considering the influence of dam size and discharge channel location, three large-scale field tests were carried out in a natural river to study the failure process and mechanism of non-cohesive soil landslide dam, and the process and mechanism of non-cohesive landslide dam breach were analyzed. The results show that the dam size and discharge channel location have a significant influence on the breach mechanism of the landslide dam. The dam failure process can be divided into three stages: the initiation stage, the development stage and the failure stage. When the discharge channel is located close to the bank, the width of the breach is smaller, and the volume of the residual dam body is larger. The more stable the dam body is, the longer the breach process time is, and the smaller the peak discharge is. This study can provide a scientific reference for the emergency disposal and risk assessment of landslide dam.

Analysis of Tunnel Lining Failure Mechanism under the Action of Active Fault

The underground structure that crosses the active fault will cause more serious damage under the dislocation of the active fault. Relying on an actual tunnel in the southwest mountainous area to establish a three-dimensional finite element model, the failure mechanism of the tunnel under strike-slip and thrust fault dislocation is revealed from the lining deformation, stress distribution, and plastic zone distribution, and the results show that the damage range of the lining distributes in the area of the fracture and the damage effect is greatly affected by the movement amount of the active fault. The lining damage under the active fault dislocation is mainly tensile damage, while the lining under the thrust fault dislocation shows compression damage on both sides of the fracture when there is a fracture with a large dip angle. The development range of plastic zone is positively correlated with the dip angle of the fracture and the amount of movement, and the development range is negatively correlated with the dip angle of the fracture and positively correlated with the amount of dislocation. The plastic zone range can be predicted, and the key monitoring range can be set according to the movement form of the active fault, the dip angle of the fracture zone, and the amount of fault movement.

Spatial distribution of rural population using mixed geographically weighted regression: Evidence from Jiangxi Province in China.

On the basis of the spatial panel data of 2000, 2005, 2010, and 2015, this study uses a mixed geographically weighted regression model to explore the spatial distribution characteristics and influencing factors of the rural (permanent) population in Jiangxi Province, China. Results show that residents in the county area have a significant spatial positive autocorrelation, especially in the lake and mountain areas and the global Moran’ I index is more than 0.05. The influence of social and economic factors presents spatial homogeneity. The effect of urbanization and per capita disposable income is negative, whereas that of agricultural output value and rural electricity consumption is positive. The influence of climate factors presents spatial heterogeneity. The influence coefficient of rainfall in 2015 ranges from [-0.061, 0.133], which has a negative effect on the southwest mountain areas and a positive effect on the northeast lake areas., The influence coefficient of temperature in 2015 ranges from [-0.110, 0.094], which has a positive effect on the southwest mountain areas and a negative effect on the northeast lake areas. The influence coefficients of wind speed and relative humidity range from [-0.090, 0.153] and [-0.069, 0.130] in 2015 respectively, which further reinforce this effect. Therefore, scholars should pay attention to the universal adaptability of economic and social factors. Moreover, they should consider the spatial difference of climatic factors to promote urbanization following the local conditions. Finally, policymakers and concerned non-governmental institutions should fully understand the sensitivity of the rural population in underdeveloped mountain areas to climate factors to promote their rational distribution.

Developing an entropy and copula-based approach for precipitation monitoring network expansion

Extreme precipitation events have been increasing in recent decades and have been causing impacts to human life and property, which requires expansion of existing networks to provide essential information for hydrometeorological analysis. This study developed an entropy and copula-based approach for precipitation monitoring network expansion, aiming at adding stations in ungauged areas with high value of monitoring (VOM), which was estimated through information content and redundancy. The approach was applied to a network in the Taihu Lake basin, China. We grouped the adjacent stations based on Thiessen polygons, computed VOM for each group and identified candidate locations for additional stations. The entropy measures, e.g., joint entropy and total correlation, required to compute VOM were estimated through the principle of maximum entropy (POME) and copula-based joint distribution fitting. We evaluated the performance of five copula families and adopted the Student t-copula as the optimal copula model. Results showed that orographic effect and network density were the main factors that influence VOM variation, i.e., high VOM appeared in the southwest mountain area and the east area with sparsely distributed stations. We also compared the results with those derived from three data quantization methods, among which the rounding technique produced consistent results. The final network schemes were generated by adding stations following a strategy that supports decision preference on the positioning scheme and station number, and were evaluated through the Kriging interpolation error. The proposed approach provides an efficient and a practical way for strengthening a precipitation monitoring system.

Risk Assessment of Highway in the Upper Reaches of Minjiang River under the Stress of Debris Flow

The southwest mountainous area is a frequent debris flow disaster area in China, which poses a serious threat to the regional roads and greatly affects the normal traffic operation and the safety of residents’ lives and property. The debris flow risk assessment of highway can quantify the threat degree of debris flow to the roads. In this paper, from the perspective of villages and towns, taking the upper reaches of Minjiang River as the research area, four factors including road network density, highway disaster resistance capacity, population density and highway cost are selected, and the weight is obtained by using entropy weight method, and the debris flow vulnerability evaluation results of highway are obtained by weighted calculation. Four indexes of debris flow density, shape factor, relative height difference and annual rainfall are selected to evaluate the debris flow hazard of highway by using the information method. Based on the vulnerability and hazard evaluation results, the risk of highway debris flow is evaluated, and the results are classified and discussed. The results show that: the risk of debris flow on the upper reaches of Minjiang River is relatively low, the overall spatial distribution shows a trend of high in the East and low in the west, and the overall risk of township roads in Wenchuan county is the highest; The risk of debris flow is generally high within -10 to 30 km from the central fault zone of Longmenshan.

哈尼梯田湿地生态系统健康评价指标体系构建

为了获得梯田湿地生态系统健康评价的指标体系，以云南红河哈尼梯田湿地为例，基于对该湿地维持机制的分析，构建了包括生态特征、功能整合、社会与政治3个方面共20个指标的健康评价指标体系以及各个指标的健康阈值分级表。同时，利用AHP层次分析法确定了各指标的权重，运用综合评价法对梯田湿地生态系统的健康状态进行评价。本研究构建的评价指标体系解决了哈尼梯田湿地生态系统缺乏健康评价指标体系和支持理论的问题，为评价该类型湿地生态系统的健康状态提供指导方法，能够依据其评价结果为后续湿地健康质量的提升及湿地的可持续利用发展提出改进策略。;Wetland plays an extremely important role in maintaining biodiversity, improving water quality, regulating microclimate, and protecting water and soil. With the unreasonable human activities, the ecological problems of wetland are becoming more and more serious, so the evaluation and diagnosis of wetland ecosystem health is extremely urgent. Hani terrace wetland is a special artificial paddy field wetland in southwest mountain area. It has not only important wetland ecological function value, but also agricultural production and national cultural value. At present, the research on Hani terrace wetland ecosystem mainly involves economic culture, ecological security and landscape tourism, while the research on ecosystem health evaluation is few. By analyzing the maintenance mechanism of the ecological balance of Hani terrace wetland and establishing a scientific health evaluation system to evaluate the health of the wetland, we can better understand the health status of the wetland, provide scientific support for the planning and utilization of the wetland and promote the sustainable development of the wetland. The unique vertical spatial structure of forest-village-terrace-river in the Hani terrace wetland is the maintenance mechanism of healthy balance of wetland ecosystem. Each part is independent and indivisible, with integrity. At this time, Hani terrace wetland ecosystem is not only the ecological subsystem of terrace wetland, but also the health evaluation of the whole forest-village-terrace river system. Based on the analysis of the maintenance mechanism, this paper constructed a health evaluation index system of 20 indicators including ecological characteristics, functional integration, social and political aspects and a health threshold grading table of each indicator. Meanwhile, AHP analytic hierarchy process is used to determine the weight of each index, and comprehensive evaluation method is used to evaluate the health status of Hani terrace wetland ecosystem later. The evaluation index system constructed in this study solves the problem of the lack of health evaluation index system and provides a guiding method for the evaluation of the health status of this type of wetland ecosystem. According to the evaluation results, improvement strategies can be proposed for the subsequent improvement of wetland health quality and sustainable utilization development of wetlands.

西南山区生态保护红线划定方法优化—基于生态地质环境脆弱性评估

PDF HTML阅读 XML下载 导出引用 引用提醒 西南山区生态保护红线划定方法优化—基于生态地质环境脆弱性评估 DOI: 10.5846/stxb202003220642 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金重大项目（41790432）；国家自然基金青年基金项目（41701114） Optimization method of ecological redline delineation in Southwest China from the view of eco-geo environment vulnerability assessment Author: Affiliation: Fund Project: Physical and Mechanical Properties of Rock and Soil on Slope Surface Under Large Gradient Environment and Spatial Pattern of Catastrophic Conditions 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:生态系统服务功能重要性评估及生态环境敏感性评估是划定生态保护红线的基本方法。以生态系统敏感性及服务功能为核心的红线划定指标体系，未能准确反映山地复杂地质环境对生态环境的影响，使得生态红线划定缺乏地质-地理过程的支撑。以地质环境与地理环境互馈为基础，构建西南山区生态地质环境脆弱性评估指标体系，以我国典型山区四川省为研究区，通过将脆弱性格局与基本方法划定的生态保护红线叠置分析，提出了基于"生态地质环境共同体"理念的山区生态保护红线划定优化方法。结果表明：生态保护红线与脆弱性评估格局基本一致，面积有差异；生态保护红线划定方法充分刻画生态系统保护格局，脆弱性格局更好反映国土空间开发保护状况，山区地质与地理过程是塑造生态红线分布格局的关键影响因素，基于生态地质环境脆弱性评估视角的2种优化方案，集中、全面反映生态系统优先保护及国土空间开发保护格局，但应合理预留人类聚居空间及生产空间。 Abstract:Assessment of ecosystem service and ecological sensitivity are the basic methods to zone the ecological redline. However, for mountainous areas with complex geological conditions, the indicator system with ecological environment and service as the core is difficult to reflect the impact of a special geological environment, which makes the ecological redline pattern lack support of the geological and geographical process. Based on the mutual feedback of geological environment and geographical environment, this study constructed the vulnerability assessment index system of the eco-geo environment in the southwest mountainous area, Sichuan Province. The ecological redline optimization method was analyzed by superposition with the assessing the frailty, based on the concept of "eco-geo environment community". The results showed that the ecological redline and vulnerability assessment pattern was generally consistent. The vulnerable area of eco-geo environment was 189700 km2, accounting for 39.1% of the research area. The total area of the ecological redline was 148000 km2, accounting for 30.45% of the research area. Geological and geographical processes in mountainous areas were key factors to shape the distribution pattern of ecological redline. Two redline optimization methods based on the vulnerability assessment of the eco-geo environment, covered an area of 197600 km2 and 241700 km2 respectively, which was consistent with the ecological security pattern of four key ecological functional areas in the main functional divisions of Sichuan Province. The two schemes reflect the priority protection of the ecosystem and the development and protection pattern of land space, but it should reserve the living space and production space reasonably. 参考文献 相似文献 引证文献

基于价值评估的黄山市生境质量时空演变特征分析

评价与分析特定区域的生境质量及其时空变化对其生态安全格局构建、可持续发展意义重大。本文以典型旅游城市黄山市为研究区，综合生态系统服务价值评价模型、基于NPP与NDVI的生境质量指数评价、InVEST生境质量评价模型、空间分析等模型与方法对黄山市1987-2017年生境质量进行研究。结果表明：（1）1987-2007年，黄山市生境质量总值持续下降，2017出现回升，但生境受到的威胁仍增加，生境最优区为北部太平湖区域，生境质量低值主要分布在各县区主城区；生境质量栅格等级变化以4等级转变为3等级为主。（2）1987-2017年，黄山市105个乡镇（街道）中有84个乡镇（街道）生境质量有所下降，主要分布在东部区域；北部环太平湖区域的乡镇为生境质量"高高"型聚集区及热点区域，屯溪区、徽州区南部、歙县、休宁县主城区的各镇为生境质量"低低"型聚集区及冷点区域。（3）黄山市城市发展对生境质量影响较大，大体上距离城市中心点越近的圈层，生境质量越差；距离黄山市旅游中心点10-20、30-40、40-50 km的3个圈层形成生境质量低值点，为旅游与城区互助发展的结果；黄山市旅游与生境质量空间分布相关性较强，旅游设施、景区核密度越高，低等级生境质量占比越高。;The evaluation and analysis of habitat quality and its spatio-temporal distribution characteristics in a specific region are of great significance in the construction of regionally ecological security pattern and sustainable development. Taking Huangshan, Anhui Province, a typical tourist city, as example, this paper analyzed the dynamic change of its habitat quality form 2007 to 2017 based on the comprehensive model and methods of ecosystem service value, habitat quality index consisting of Net Primary Productivity(NPP) and Normalized Difference Vegetation Index(NDVI), InVEST habitat quality assessment model and spatial analysis methods. The results showed that: (1) from 1987 to 2007, the total value of habitat quality in Huangshan City continued to decline, while the total value of habitat quality rose in 2017, but the threat to habitats continued to increase. The high-quality habitat areas were the Taiping Lake in the north, but the low quality of habitats was mainly distributed in the urban areas of the counties. And the change of habitat quality grid grade was mainly from 4 grade to 3 grade in1987-2017. (2) The habitat quality of 84 out of 105 villages and towns (streets) in Huangshan City declined from 1987 to 2017, mainly in the eastern region. The areas of High-High habitat quality type clusters and hot spot areas were mainly located in the villages and towns around Taiping lake in the north of Huangshan, while the areas of Low-Low habitat quality type clusters and cold spot areas were located in and the towns of Tunxi district, Huizhou district, Shexian county, and Xiuning county. The secondary hot spot township did not appear in 2007 in the southwest mountain areas. (3) The urban development of Huangshan City had a great impact on the quality of habitat. Generally, the closer to the center of the city, the worse the habitat quality. The three circles of 10-20, 30-40, and 40-50 km away from the tourism center of Huangshan City formed the low value points of habitat quality, which was the result of the mutual development of tourism and urban areas. What is more, there was a strong correlation between tourism and habitat quality spatial distribution in Huangshan City. The higher the nuclear density of tourism facilities and scenic spots, the higher the proportion of low-grade habitat quality.

Study on mixing interface of continuous large drop and U-shaped product pipeline

In the long-distance pipeline of product oil, gasoline and diesel oil are transported in batches. Due to the large difference of physical properties between the two kinds of oil products, there will be oil mixing at each interface. Because the index parameters of mixed oil do not meet the sales standard, it is necessary to track the interface accurately, so as to provide necessary reference for cutting mixed oil. The topography of southwest mountainous area is characterized by continuous large drop and U-shape, which brings difficulties to batch tracking of product oil pipeline. The previous method is not suitable for this type of pipeline. Therefore, it is necessary to re study the batch tracking method of this type of product pipeline, and use vs2019 to write batch tracking software for continuous large drop and U-shaped product pipeline based on this method. The batch tracking error of the software for this type of pipeline is within the acceptable range, which can provide more accurate reference for the operation control personnel

Spatiotemporal LUCC Simulation under Different RCP Scenarios Based on the BPNN_CA_Markov Model: A Case Study of Bamboo Forest in Anji County

Simulating spatiotemporal land use and land cover change (LUCC) data precisely under future climate scenarios is an important basis for revealing the carbon cycle response of forest ecosystems to LUCC. In this paper, a coupling model consisting of a back propagation neural network (BPNN), Markov chain, and cellular automata (CA) was designed to simulate the LUCC in Anji County, Zhejiang Province, under four climate scenarios (Representative Concentration Pathway (RCP) 2.6, 4.5, 6.0, 8.5) from 2024 to 2049 and to analyze the temporal and spatial distribution of bamboo forests in Anji County. Our results provide four outcomes. (1) The transition probability matrices indicate that the area of bamboo forests shows an expansion trend, and the largest contribution to the expansion of bamboo forests is the cultivated land. The Markov chain composed of the average transition probability matrix could perform excellently, with only small errors when simulating the areas of different land-use types. (2) Based on the optimized BPNN, which had a strong generalization ability, a high prediction accuracy, and area under the curve (AUC) values above 0.9, we could obtain highly reliable land suitability probabilities. After introducing more driving factors related to bamboo forests, the prediction of bamboo forest changes will be more accurate. (3) The BPNN_CA_Markov coupling model could achieve high-precision simulation of LUCC at different times, with an overall accuracy greater than 70%, and the consistency of the LUCC simulation from one time to another also had good performance, with a figure of merit (FOM) of approximately 40%. (4) Under the future four RCP scenarios, bamboo forest evolution had similar spatial characteristics; that is, bamboo forests were projected to expand in the northeast, south, and southwest mountainous areas of Anji County, while bamboo forests were projected to decline mainly around the junction of the central and mountainous areas of Anji County. Comparing the simulation results of different scenarios demonstrates that 74% of the spatiotemporal evolution of bamboo forests will be influenced by the interactions and competition among different land-use types and other driving factors, and 26% will come from different climate scenarios, among which the RCP8.5 scenario will have the greatest impact on the bamboo forest area and spatiotemporal evolution, while the RCP2.6 scenario will have the smallest impact. In short, this study proposes effective methods and ideas for LUCC simulation in the context of climate change and provides accurate data support for analyzing the impact of LUCC on the carbon cycle of bamboo forests.

A 10-Year Climatology of Mesoscale Convective Systems and Their Synoptic Circulations in the Southwest Mountain Area of China

AbstractHourly blackbody temperature data from the warm seasons (May–September) of 2009–18 were used to detect mesoscale convective systems (MCSs) generated in the southwest mountain area (elevation ≥ 500 m) of China. A total of 3059 MCSs were grouped into four categories (C1, C2, C3, and C4) according to their generation positions using K-means clustering. Major characteristics of the four types of MCSs and their synoptic environmental conditions were investigated. The MCSs had a peak in July and a minimum in May, and usually lasted from 3 to 21 h. The C1 MCSs generated in the northeast of the Tibetan Plateau developed faster, were largest, and had a longer lifespan. The C2 and C4 MCSs had greater intensity and were initiated in the southeast of the Tibetan Plateau and the west of the Yungui Plateau, and near the Wuling and Xuefeng Mountains, respectively. The C3 MCSs initiated in the Qinling, Ta-pa, and Wushan Mountains were smallest. The C1 and C2 MCSs contributed more than 30% to total precipitation, which was more than the C3 and C4 MCSs (<25%), and the contribution rate of MCSs to short-duration heavy rainfall affected by local MCSs was over 60%. Composite synoptic circulations of the four types of MCSs showed several factors, including the locations and intensities of cyclones in the Bay of Bengal and high pressure in the Indochina Peninsula in the low-to-middle troposphere, and vortexes or southwesterly winds in the low-level troposphere, regulate the location and intensity of convection.

Evaluating the impact of land fragmentation on the cost of agricultural operation in the southwest mountainous areas of China

Given the background of the increasing opportunity cost of farming and the popularization of labour-saving technology, increased fragmentation has gradually become a key factor in the devaluation and abandonment of land assets. To systematically identify the costs of fragmentation, we use a series of indicators such as the number of plots, the Simpson index, the plot-homestead distance and the total minimum commuting time from the homestead to all plots to measure the extent of fragmentation. A translogcost function is developed and estimated using survey data from three periods, 2011, 2014 and 2017; the data include an effective sample of 1064 household-year observations involving 6599 plot-year observations in Chongqing, China. The extent of fragmentation in the mountains of southwest China is quite serious compared with that in other countries and regions. The Simpson index is 0.63, and on average, 6.06 mu (1 mu = 666.67 m2 or 1 mu = 1/15 ha) of cultivated land is distributed in 6.16 plots, while the total minimum commuting time from the homestead to all plots is approximately 45 min. An increase of one standard deviation in the number of plots, the Simpson index or total minimum commuting time would lead to cost increases of 7.1 %, 15.1 % and 12.2 %, respectively, if other conditions remain unchanged. The channel for the above result involves the changes in the cost share of inputs caused by fragmentation, which increase the labour cost share and reduce the machinery cost share. There is an inverted U-shaped relationship between farm scale and production cost with an inflection point at 47 mu; that is, costs begin to decrease when the scale exceeds 47 mu. However, the average farm scale is currently only 6.06 mu. In addition, production costs can be significantly reduced by renting-in land and implementing land consolidation. To reduce land system-induced costs in mountainous areas, the government should rationally consolidate land to achieve moderate-scale management, reduce the transaction costs of land transfers and popularize machinery suitable for complex terrain.

Research on the Path and Countermeasures of Accelerating the Poverty Alleviation to a Well-off Society for the Characteristic Agricultural Industry in the Southwest Mountainous Area

With the deepening of the implementation of the “precision poverty alleviation” strategy and the continuous development of China ’s ethnic minority characteristic industry construction, more and more characteristic agricultural industry and poverty alleviation project are receiving attention. The development of characteristic agriculture is the strategic adjustment of agricultural structure in the southwestern region. The rapid development of pillar industries in the characteristic agricultural industry will inevitably promote the scale of commodity production bases and the rational allocation of resources, realize the multi-level and multi-channel development and utilization of agricultural resources, and meet the diverse and high-quality market needs. This article aims at the current situation of the characteristic agricultural industry in the southwest mountainous area, which studies the path and related policies of poverty alleviation and well-off in southwestern China. Taking Chengdu-Chongqing Economic Zone as an example, the policy background of industrial poverty alleviation, the main methods of industrial poverty alleviation, the main problems, their causes, and countermeasures analyzed and discussed in this paper. Through the research and analysis of the Chengdu-Chongqing Economic Zone samples, this paper proposes the path of industrial poverty alleviation in ethnic areas, which has a direct role in promoting poverty alleviation in the southwest mountain area. The research of poverty alleviation problem in this area will be reference for poverty alleviation in other poverty areas and ethnic minority areas.

Study on Long-term Operating Mechanism of Rural Drinking Water Projects in Southwest Mountainous Areas

The rural drinking water project is an important manifestation of building a new socialist countryside and a policy of benefiting the farmers to improve the quality of life. However, there are many problems in the operation and management of rural drinking water projects, including incomplete management systems, inadequate drinking water quality, and unreasonable collection of water charges. These problems are not conducive to the long-term operation of drinking water projects. This article proposes the corresponding management measures aiming at the above problems in the operation and management of rural drinking water projects.

Farmland marginalization and its drivers in mountainous areas of China

The marginalization phenomenon characterized by devaluation and abandonment of farmland began to appear in mountainous areas. The purpose of this study was to reveal the extent of farmland marginalization and its drivers, and a two-stage tracking survey involving 7045 plots from 1012 households from the southwest mountainous areas of China in 2011 and 2018 by employing a variety of metrics and binary Logit model. The results showed that the average profit and rent of cultivated land per mu (1 mu = 666.67 m2) presented a significant downward trend in study areas. With the continuous decline of farmland profit, the utilization of land has undergone a significant transformation, such as the transformation of crops from labour-intensive to machine-intensive. The ratio of plots transferred out with free rent increased from 3/5 to 4/5 and the rate of abandonment increased from 21.6% to 27.2% during the study period. Farmland marginalization characterized by land devaluation and abandonment is intensifying in mountainous areas of China in recent years. Plot levels such as distance from the residence, damaged by wild boar, low plot quality and labour famine are the key factors of farmland marginalization such as abandonment, while the rising cost of farming is the root cause. The driver of marginalization was that urbanization increased labour cost, farming profits declined until they became losses, and the farmland was finally abandoned. Nowadays, farmland marginalization is not an unique phenomenon in mountain areas of China and it is more common all over the world. The government should stop large-scale farmland reclamation projects in mountainous areas of China and we can compensate for the loss of farmland by improving the quality and utilization efficiency of the remaining farmland.

Satellite-Based Estimation of Daily Ground-Level PM2.5 Concentrations over Urban Agglomeration of Chengdu Plain

Monitoring particulate matter with aerodynamic diameters of less than 2.5 μm (PM2.5) is of great importance to assess its adverse effects on human health, especially densely populated regions. In this paper, an improved linear mixed effect model (LMEM) was developed. The model introduced meteorological variable, column water vapor (CWV), which has as the same resolution as satellite-derived aerosol optical thickness (AOT), to enhance PM2.5 estimation accuracy by considering spatiotemporal consistency of CWV and AOT. The model was implemented to urban agglomeration of Chengdu Plain during 2015. The results show that model accuracy has been improved significantly compared to linear regression model (R2 = 0.49), with R2 of 0.81 and root mean squared prediction error (RMSPE) of 15.47 μg/m3, mean prediction error (MPE) of 11.09 μg/m3, and effectively revealed the characteristics of spatiotemporal variations PM2.5 level across the study area: The PM2.5 level is higher in the central and southern areas with dense population, while it is lower in the northwest and southwest mountain areas; and the PM2.5 level is higher during autumn and winter, while it is lower during spring and summer. The product data in this paper are valuable for local government pollution monitoring, public health research, and urban air quality control.

The Features of Rural Labor Transfer and Cultural Differences: Evidence from China’s Southwest Mountainous Areas

Large-scale rural labor transfer is considered an important means of promoting urbanization and poverty alleviation; however, it has been difficult to fully reveal the complexity of mountain labor transfer using traditional theory. In this study, macrostatistics and microsurvey data were employed to conduct an empirical analysis of rural labor transfer in Xichang, highlighting the regional features of rural labor transfer in the southwest mountainous areas of China. The results show that the employment structure of rural labor is dominated by agriculture; however, its proportion is decreasing annually. The development of secondary and tertiary industries significantly contributes to the non-agricultural employment of rural laborers, who transfer mainly to the building, industry, and consumption fields—especially consumption, which has the greatest ability to absorb surplus rural labor. Migration of the population and farmers’ per capita net income promotes rural labor transfer, while the amount of rural labor, the urbanization rate in townships, agricultural development, and the topography have lagged effects on the process. This study argues that rural labor transfer in the mountains has regionality, multi-pattern, and gradient features; therefore, the promotion of rural labor transfer should consider local urbanization and poverty alleviation in such a manner that aligns with the local natural and socioeconomic conditions of the mountainous areas.

Experimental and numerical analyses on working performance of a high arch dam with deep-seated joints: Yebatan arch dam, China

High arch dams commonly face complicated geological conditions at the dam site, which is particularly prominent in numerous projects in the southwest mountainous area of China. The deep-seated joint is a special geological defect caused by unloading fracturing of the deep rock mass, which is unfavourable to the working performance of high arch dam projects. The Yebatan arch dam is a world-class high arch dam, situated in a deeply carved V-shaped gorge with deep-seated joint zones in both banks. In this paper, both geomechanical model test and numerical analysis are carried out to study the working performance of the Yebatan arch dam and abutment, which are affected by the deep-seated joint zones. The research results demonstrate that the deep-seated joint zones have a significant effect on the arch dam and abutment working performance. It is highly dependent on the location of the class IVS strong relaxed rock mass and the combination with faults. The class IVS strong relaxed rock mass in the left abutment has a great impact on the deformation of arch dam and abutment, and fault f29 (f74) plays a dominant role in controlling the anti-sliding stability of the right abutment. Subsequently, a kind of concrete replacement measure is proposed in order to treat these project weaknesses. The additional numerical analysis results indicate the deformation and stability performance of arch dam and abutment are greatly improved after reinforced. The reinforcement measure is effective for Yebatan project.

Research on Optimization Design of Railway Bridge Damping Tenon in High-intensity Seismic Area

The railway bridge damping tenon device can not only provide lateral, longitudinal and vertical stiffness, which means that the displacement of main beam will be effectively limited under earthquakes. The energy dissipation system formed by shock-absorbing bearing-damping tenon also has significant energy consumption performance, which can meet the seismic demand of the bridge in the high seismic intensity zone of the southwest mountainous area. However, the gap and yield force of the damping tenon and the design parameters of shock-absorbing bearing have a significant impact on the seismic isolation effect and on the limitation of the main beam displacement. Therefore, this paper takes the typical high-speed railway bridge in the southwest mountainous near-fault zones as research object, and a refined finite element analysis model of the bridge system considering the nonlinear dynamic coupling effects such as geometry, material and contact is established to study the most suitable design parameters of damping tenon. In general, the shock absorption rate of the pier bottom bending moment increases with the increases of the tenon’s gap and decreases with the increase of the tenon’s yield force. However, the determination of the damping tenon’s design parameters requires a comprehensive consideration of displacement limitation of the main beam. The research results can provide a basis for the optimization design of railway bridge damping tenon device in the future.