Mountainous Regions Of China Research Articles

Utilization of Tunnel Waste Slag for Cement-Stabilized Base Layers in Highway Engineering.

The rapid expansion of highway infrastructure in the mountainous regions of China has led to a significant increase in tunnel construction, generating substantial amounts of tunnel waste slag. Concurrently, the development of transportation infrastructure has created a critical shortage of natural aggregates, necessitating the exploration of alternative sustainable sources. This study aimed to conduct a comprehensive evaluation of the physical and mechanical properties of tunnel waste slag and explore its potential for utilization in cement-stabilized base courses for highway engineering applications. The uniaxial compressive strength of the parent rock (tunnel waste slag) ranged from 81 MPa to 89 MPa in the desiccated state, indicating its suitability for use as a construction material. This study also determined the maximum dry density (2.432 g/cm3) and optimal moisture content (5.4%) of cement-stabilized mixtures incorporating recycled aggregates derived from tunnel waste slag. The splitting tensile strength of these mixtures at 28 days varied from 0.48 MPa to 0.73 MPa, demonstrating robust mechanical performance. Moreover, the unconfined compressive strength of these mixtures escalated from 7.0 MPa at 7 days to 11.0 MPa at 90 days, signifying a substantial enhancement in strength over time. These results validate the viability of utilizing tunnel waste slag in highway engineering and furnish valuable insights for designers, concrete manufacturers, and construction firms engaged in the development of cement-stabilized aggregate base courses.

Where Is the Place to Call Home? The Diasporic Writings of Hmong Americans

ABSTRACT The Hmong are an ethnic group with a rich cultural and historical background. They are primarily found in Southeast Asia, particularly in the mountainous regions of China, Vietnam, Laos, and Thailand. Since the end of the Vietnam War in 1975, the Hmong have immigrated to the United States in large numbers as war refugees. The process of their integration into the new culture has engendered the formation of Hmong English writing. This body of literature mainly includes autobiographies, short stories, essays, and poems, most of which depict the Hmong experience of exile, and whose central preoccupation is the pursuit of a homeland. Focused exclusively on the literary works of Hmong Americans, this paper examines classic and experimental texts to amplify independent narratives. Drawing from diaspora literature scholarship by Stuart Hall and Homi K. Bhabha, it positions Hmong American literature as a representative form of diasporic writing. It seeks to unravel the complexities of their cultural transition, identity, and the role of literature in constructing narratives and opens up fresh dimensions in understanding its unique features and contributions.

ОРГАНИЗАЦИЯ АРХИТЕКТУРНОЙ СРЕДЫ ОБЩЕСТВЕННЫХ ПРОСТРАНСТВ В УСЛОВИЯХ СЛОЖНОГО РЕЛЬЕФА

The mountain landscape distinguishes the location of urban routes, the functional-spatial structure and layout of public areas from the design of an urban environment on flat terrain. This study examines the issues of rational use of urban areas in conditions of complex terrain using the example of the territory of the largest city of Chongqing, located in the central part of China. The research is based on an integrated approach, methods of urban planning analysis and functional-spatial modeling. Various aspects of the transformation of complex natural landscapes to expand public urban spaces and form their identity are analyzed using the example of public spaces in the structure of high-density residential development in Chongqing. The study identified the characteristic problems of the planning organization of public areas on difficult terrain (insufficient insolation, lack of green areas, non-standard location of transport infrastructure, irrational organization of pedestrian traffic, lack of public access to public areas, isolation and incoherence of public spaces, etc.). Functional planning models for the organization of public recreational spaces are proposed, which are promising for use both in areas of existing high-density development and for the development of undeveloped territories in the mountainous regions of China. Prospective directions for the development of public spaces in the Baixiangju residential area in Chongqing have been identified.

Exploring coordinated development and its driving factors between carbon emission and ecosystem health in the southern hilly and mountainous region of China

Achieving “carbon neutrality” is an inevitable requirement for tackling global warming. As one of the national ecological barriers, the southern hilly and mountainous region (SHMR) shoulder the important mission of taking the lead in achieving “carbon peak” and “carbon neutrality”. Thus, it has important scientific significance to explore and analyze how to coordinate ecological development under the background of “double carbon action”, and it is a key step to ensure that the region achieves synergistic development of promoting economic development and improving ecosystem health. Therefore, in this study, we aimed to address these gaps by adopting a refined grid scale of 10 km × 10 km to explore the spatial-temporal distribution characteristics of carbon emissions and ecosystem health. Additionally, we established a coupling coordination model of carbon emissions intensity (CEI) and ecosystem health index (EHI) to assess the impact of natural and socio-economic factors on the coupling coordination degree (CCD) in different regions. Our findings are as follows: 1) In the SHMR region, the EHI exhibited a progressive development trend, with spatially increasing values from the south to the north. 2) The spatial discrepancy in CEI has been on the rise, which assumed an increase of 4.69 times, and with an increasingly pronounced pattern of spatial imbalance. Carbon emissions tend to concentrate more in the eastern and northern areas, while they are comparatively lower in the western and southern regions. 3) The R2 of geographical weighted regression model (GWR) is all above 0.8, and the CCD between CEI and EHI demonstrated a positive developmental state. However, most regions still displayed an imbalanced development, albeit with a slight increase in areas exhibiting a more balanced development state. 4) The driving forces of natural and socio-economic factors had a dual-factor and non-linear enhancement effect on the CCD. The influence of natural factors on CCD has gradually diminished, whereas the influence of socio-economic factors has progressively strengthened.

Thermal Comfort Comparison and Cause Analysis of Low-Temperature High-Humidity Indoor Environments of Rural Houses in Gansu Province, China

Low temperatures and high humidity often occur in the northern basins and mountainous regions of China. This research reveals a common winter indoor environment in this rural areas characterized by low-temperature and high-humidity indoor thermal conditions. Improving this environment directly with equipment would inevitably result in significant energy consumption. Therefore, comprehending the thermal performance mechanisms of different structural building materials is of vital importance as it provides crucial baseline values for environmental improvement. This study conducted a survey utilizing user questionnaires, resulting in the collection of 214 valid responses. Additionally, a local experiment regarding thermal comfort was conducted. Simultaneously, this study monitored the indoor physical environments of these houses (a sample of 10 rooms was taken from earth houses and 12 rooms from brick houses). Parameters measured on site included air temperature, relative humidity, light illumination, and CO2. The results showed that the humidity inside the earth houses is more stable and regression models can be developed between thermal sensations and temperature for long-term residents. The residents of these earth houses are more sensitive to temperature step. In contrast, the residents of brick houses, experiencing greater environmental variability, demonstrated lower sensitivity and greater adaptability to temperature changes. In addition, heating from bottom to top is more comfortable and healthier for the residents of brick houses in Gansu. Moreover, it is more favorable for the inhabitants’ livelihood to regulate the temperature steps to a maximum of 4 °C. This study provides valuable reference information for the future design of houses in low-temperature and high-humidity environments.

Peasant traders, migrant workers and “supermarkets”: Low‐cost provisions and the reproduction of migrant labor in China

AbstractThis article analyzes the social and spatial dynamics of the mobile trade in low‐cost goods by rural people from a mountainous region of China's Zhejiang province and how these interact with the mobility and social reproductive patterns of the rural–urban migrant workers they cater to. Also formally categorized as peasants, the traders not only supply the goods necessary for the maintenance of the workers but also of their spatially divided household, thus contributing to the reproduction of migrant labor power more generally. In doing so, they assume mobility trajectories that align with those of factory production and experience familial trade‐offs commonly experienced by migrant workers. Meanwhile, the provision of low‐cost goods to migrant workers has enabled a thriving economy employing peasant families for whom agricultural livelihoods slowly disappear. These dynamics indicate the mutual connection between waged and self‐employed labor that works in the interest of capital accumulation at the same time with the differentiation of migrant labor. As in other comparable Asian contexts, their connection lies at the heart of the state‐sponsored production regime premised on the low‐cost reproduction of flexible migrant labor.

Changes in snowpack of the Changbai Mountain region over the last decade in reaction to global warming

As greenhouse gas emissions have been mounting in recent years, the issue of global warming has become more and more serious, sparking a great deal of concern. Among the effects of global warming, the melting of snowpack is particularly pronounced. However, most of the current researches focus on vegetation and biodiversity, and there are some gaps in studies of snow in the mountainous regions of China. This paper analyzes the Landsat8 satellite images of Changbai Mountain area in the past 10 years through QGIS and programming algorithms to study the trend of snowpack change, the correlation between snow melting and vegetation change and causes of snow melting. The analytical methods used in this paper include NDSI, NDVI, supervised classification and image binarization. From 2014 to 2023, the snow-covered areas in Changbai Nature Reserve have decreased dramatically, especially in northwestern part, middle part and edges of Changbai Mountain. The change rate of snowpack has reached a significant 13.979%. The vegetation area shows an increasing trend and is negatively correlated with snowpack change. In order to alleviate the challenge of snow melting, ecological engineering, new energy sources and rigorous regulation of human activities are all essentially necessary. In the future, it is expected that the research in this paper will have a profound positive impact on the ecological management of the Changbai Mountain region, the conservation of snow resources and the mitigation of global warming.

Mapping the spatial and temporal patterns of fallow land in mountainous regions of China

ABSTRACT The rapid growth of the global population has resulted in a continuous increase in cropland intensity and a shortening of the fallow period as part of the cropland rotation cycle. Yet, there is a lack of systematic knowledge on the extent of fallow lands, particularly in complex landscapes, such as the mountainous regions of China. To fill this knowledge gap, taking Yuanyang County (YYC), Yunnan Province, China, as a case study, we tested a method to identify the spatial-temporal distribution of fallow land by mapping cropland with Landsat data. The overall accuracy of land cover classification, including cropland, ranged between 90.1% and 95.8% from 1998 to 2019. The average accuracy of fallow plots was 75.7% from 2001 to 2019. The annual fallow rate varied between 8.3% and 54.3%, with an average of 20.7%. Kernel density estimated with the probability density function showed that fallow varied between 5 and 13 blocks per km2, gradually decreasing from the central area to the periphery. Increasing elevation, the low value of regional domestic products, and the increased distance to rural settlements were closely related to the higher proportions of fallow land. The approach presented here can be applied to map fallow land in other regions.

The complete chloroplast genome of two traditional medical plants: Asparagus cochinchinensis (Lour.) Merr. and Asparagus dauricus Fisch. ex Link

Asparagus cochinchinensis (Lour.) Merr. and Asparagus dauricus Fisch. ex Link are two traditional medical plants with therapeutic effects, distributed in mountainous regions of China. In the current study, the complete chloroplast (cp) genomes of A. cochinchinensis and A. dauricus were sequenced on the Illumina Hiseq 2500, and obtained with a length of 157,095 bp and 156,918 bp, respectively, both containing a large single-copy region and a small single-copy region separated by a pair of inverted repeat regions. The cp genome of A. cochinchinensis has 132 annotated genes including 86 protein-coding genes, 38 tRNA, and eight rRNA genes. A. dauricus has 112 annotated genes containing 78 protein genes, 30 tRNA, and four rRNA genes. The maximum-likelihood tree was reconstructed with 17 species, indicating that A. cochinchinensis is a sister group to the clade including A. officinalis to A. racemosa. This clade includes five species of Asparagus.

Response of Ecosystem Health to Land Use Changes and Landscape Patterns in the Karst Mountainous Regions of Southwest China.

The quantitative assessment of ecosystem health is important for interpreting the ecological effects of land use changes and formulating effective measures of sustainable ecological development by policymakers. This study investigated the response of ecosystem health to land use changes and landscape patterns in the karst mountainous regions of southwest China by taking Guiyang City as a case study area and assessing the spatial and temporal changes in ecosystem health from 2008 to 2017 using the vigor–organization–resilience model; it analyzed the influence of land use changes and landscape patterns on ecosystem health using spatial overlay analysis, the Dunnett’s T3 test, and the Spearman correlation analysis. The results show that the land use structure dramatically changed, with a trend of a sharp decrement of farmland and rapid increment of forestland and construction land due to rapid urbanization and ecologization. The overall ecosystem health was at a relatively strong level, with the average value greater than 0.6. The deterioration of ecosystem health was attributed to the expansion of construction land and farmland and the degradation of forestland, while the increment of forestland was the major contributor to the improvement of ecosystem health. The ecosystem health of the forestland + farmland landscape was significantly superior to that of forestland + construction land and construction land + farmland landscapes. Moreover, each landscape configurations had a significant positive or negative correlation with the ecosystem health. This study provides a valuable reference for formulating sustainable environmental management strategies in karst mountainous regions in China.

南方丘陵山区生态安全格局构建与优化修复——以瑞金市为例

PDF HTML阅读 XML下载 导出引用 引用提醒 南方丘陵山区生态安全格局构建与优化修复——以瑞金市为例 DOI: 10.5846/stxb202106061490 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41861036）；中国博士后科学基金面上一等资助项目（2018M630738）；江西省自然科学基金项目（20192BAB213023）；江西省教育厅科技项目（GJJ200504） Construction, optimization and restoration of ecological security pattern in the southern hilly and mountainous region of China: A case study in Ruijin City Author: Affiliation: Fund Project: National Natural Science Foundation of China (No.41861036); the 63th Batch of China Postdoctoral Science Foundation (No.2018M630738); the Natural Science Foundation of Jiangxi Province (20192BAB213023); and the Science and Technology Project of Education Department of Jiangxi Province (GJJ200504) 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:构建科学合理的生态安全格局、落实生态保护修复与空间优化是促进区域生态系统健康运行和社会经济可持续发展的重要途径。以南方丘陵山区瑞金市为例，综合生态敏感性评价与最小阻力模型，解构瑞金市生态安全格局及其自然生态与社会经济特点，并提出生态保护修复与空间优化方案。结果显示：（1）瑞金市生态源地共有123.22km2，占总国土面积5%，主要为重要山林地和水域，环绕中部盆地呈卫星状分布；（2）潜在廊道119条，生态节点72个，在周边山地呈闭合网络状，但中部盆地廊道单一、节点密集，网络连通性较低；（3）瑞金市是典型的高原型阻力面，中部盆地城镇发展区、沟域经济延伸带、西部工矿挖采点生态阻力高、源地辐射弱，应生态预警与重点修复。瑞金市生态保护修复与空间优化应宏观统筹、分区推进、精细落实，划分生态修复核心区、生态监测预警区、生态保护缓冲区和生态保护重点区，明确空间管控原则、分区推进生态保护，围绕"源地-廊道-节点"落实生态修复。 Abstract:Establishing ecological security patterns, and implementing ecological restoration and spatial optimization are important ways to promote the health of regional ecosystems and the sustainable development of society and economy. Using Ruijin City, a southern hilly and mountainous region of China, as a case, this study demonstrated the regional ecological security patterns and the bio-physical and socio-economic characteristics through ecological sensitivity assessment and a least resistance model. Then the strategies for ecological restoration and spatial optimization were finally proposed. The results show that:(1) the identified ecological source areas in Ruijin City is 123.22km2, accounting for 5% of the total area. They are mainly composed of important mountainous forests and water bodies, and distributed around the central basin. (2) There are 119 potential corridors and 72 ecological nodes, which form a closed network in the surrounding mountains. However, the central basin only possesses a single corridor with dense nodes and low network connectivity. (3) The mountainous Ruijin City turns to be a typical plateau resistance surface. The urban areas under development in the central basin, the economic extension zone in the gully area, and the west mining areas, where the ecological resistance is extremely high while the radiation from the ecological source is weak, should be ecologically pre-warned and restored with priority. In terms of spatial optimization and ecological protection and restoration in Ruijin City, the work should be arranged macroscopically as a whole, propelled regionally and implemented meticulously. Moreover, the ecological restoration core area, the ecological monitoring and pre-warning area, the ecological protection buffer area, and the ecological protection key area should be classified with distinct principles for spatial regulation. Specific countermeasures for regional ecological protection and restoration should be based on the "source-corridor-node" pattern. 参考文献 相似文献 引证文献

山地景观遗传学研究文献综述

PDF HTML阅读 XML下载 导出引用 引用提醒 山地景观遗传学研究文献综述 DOI: 10.5846/stxb202106191631 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金面上项目31970431；生态环境部生物多样性调查、观测与评估项目（2019HJ2096001006） Research progress and future outlook of mountain landscape genetics studies Author: Affiliation: Fund Project: 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:山地生态系统是生物多样性分布与保护的热点。山地景观遗传学（Mountain Landscape Genetics）研究在山地景观尺度上野生生物的种群遗传格局及其驱动机制和影响因素，是景观遗传学（Landscape Genetics）的重要分支。山地景观遗传学研究对于深入理解物种的空间遗传结构、形成过程、物种形成与分化机制具有重要意义与价值，同时可以为珍稀濒危物种和山地生物多样性的有效保护与管理提供科学指导。为了更好地掌握目前山地景观遗传学的发展趋势与重点研究问题，为未来生物多样性与山地生态系统的保护管理提供科学参考，基于对Web of Science核心数据库和中国知网数据库的系统检索，全面汇总分析了1999-2020年山地景观遗传学领域发表的192篇英文文献与31篇中文文献。结果显示，该领域自2008年起迅速发展，截至2020年共有46个国家的研究机构发表了山地景观遗传相关研究，研究热点地区包括北美洲的落基山脉、内华达山脉、阿巴拉契亚山脉，欧洲的阿尔卑斯山脉、比利牛斯山脉，以及亚洲的喜马拉雅-横断山脉。研究对象类群涵盖真菌、植物、节肢动物、脊椎动物，其中脊椎动物是研究发表最多的类群，占发表文献总数的62.0%；脊椎动物中，又以对哺乳类（占脊椎动物发表文献总数的52.9%）与两栖类（23.5%）的研究最多。目前主要的研究方向包括：（1）识别山地景观中的基因流路径或阻碍；（2）量化山地景观特征对种群遗传结构时空变化的影响。中国是发表山地景观遗传学文章数量最多的亚洲国家，近十年来相关研究发展迅速，研究类群以植物（占在中国发表文献总数的62.3%）与脊椎动物（35.8%）为主，对脊椎动物的研究中以两栖动物为最多（占所有脊椎动物发文数量的52.6%），研究区域主要集中在喜马拉雅-横断山脉与秦岭。本文进一步对目前山地景观遗传学研究中存在的空缺及未来重点关注问题提出建议。 Abstract:Mountain ecosystems are hotspots of biodiversity distribution and conservation. Mountain landscape genetics is an important branch of the subject Landscape Genetics, which studies the genetic patterns of wild populations, their underlining mechanisms and influencing factors at the mountain landscape scale. Mountain landscape genetics research is of great significance for in-depth understanding of the formation of species’ spatial genetic structure, speciation and differentiation mechanism, and can provide important guidance for the effective conservation and management of rare and endangered species and mountain biodiversity. To better understand the development trend and key research issues in the field of mountain landscape genetics, and to provide scientific reference for protection and management of biodiversity and mountain ecosystems in the future, we systematically reviewed relevant studies retrieved from the core database of Web of Science and China National Knowledge Infrastructure (CNKI). A total of 192 English and 31 Chinese literatures in the field of mountain landscape genetics published from 1999 to 2020 were summarized and analyzed. The results showed that the field has been developing rapidly since 2008, with numerous research institutions from 46 nations involved in these published studies. The geographical research hotspots included the Rockies, Sierra Nevada, and Appalachians in North America, the Alps and Pyrenees in Europe, and the Himalaya-Hengduan Mountains in Asia. The studied taxa included fungi, plants, arthropods and vertebrates, where vertebrates were the most studied taxon accounting for 62.0% of the total number of published English articles. Among the vertebrates, mammals (accounting for 52.9% the total number of vertebrate articles) and amphibians (23.5%) were the most studied taxa. Current research directions of mountain landscape genetics mainly include: (1) identifying paths or barriers of gene flow in the mountain landscapes; and (2) quantifying the effects of mountain landscape characteristics on the temporal and spatial variations of population genetic structure. Of all Asian countries, China has published the largest number of articles on mountain landscape genetics. Research on mountain landscape genetics in China has been rapidly advancing in the past decade, with plants (accounting for 62.3% the total number of Chinese studies) and vertebrates (35.8%) being the focal taxa. The largest number of vertebrate studies were conducted on amphibians (accounting for 52.6% the total number of vertebrate publications). Himalayas and Qinling Mountains were the focal mountainous regions in China. In this review, we also provide suggestions about the gaps existing in mountain landscape genetics and the key research issues to be addressed for current and future studies. 参考文献 相似文献 引证文献

Flow depth, velocity, and sediment motions in a straight widened channel with vegetated floodplains

Experiments were conducted in a straight channel that widens from a single channel to a compound channel based on a real navigation channel with a similar shape in a mountainous region of China. Flow entered the single channel and then the compound channel with vegetated floodplains. The channel widened at the interface between the single and compound channels, resulting in different flow depths between the single and compound channels. An equation was proposed to estimate the percentage that the flow depth decreased from the single channel to the compound channel. Vegetation increased the floodplain resistance, causing more water to flow in the main channel and yielding a greater mean velocity in the main channel relative to the nonvegetated case. The velocity reached a maximum and gradually decreased until reaching a constant in the compound channel. Sediment motion (bedload vs. deposition) was determined by the local bed shear and the critical bed shear. Sediment was deposited in the compound channel at the position where the local bed shear was smaller than the critical bed shear. When the floodplains were vegetated, the increase in the main channel velocity enhanced the local bed shear, which surpassed the critical bed shear; thus, deposited sediment was reinitiated and moved downstream, and no deposition was observed.

Influences of Topographic Factors on Outcomes of Forest Programs and Policies in a Mountain Region of China: A Case Study

In China, the successive government has implemented ambitious programs and policies to reverse the decline in forest cover. As an essential source of freshwater and an ecological barrier for Beijing, Zhangjiakou City has implemented several forest expansion strategies. Topographic conditions in this mountainous area have generated spatially heterogeneous afforestation outcomes. Quantifying the impact of these conditions on implemented forest programs could improve ecological restoration strategies of Chinese mountain areas. Using remotely sensed data from the Landsat 5 Thematic Mapper and the Landsat 8 Operational Land Imager, we generated land cover data to identify forest cover changes in Zhangjiakou City in 1989, 2000, and 2015. Forest cover data, topographic information (elevation, slope, aspect, land relief, and terrain niches), and spatial statistical models (geographically weighted regression [GWR]) were used to analyze re- and afforestation over 2 periods (1989–2000 and 2000–2015). The results show that forest cover in Zhangjiakou City increased by one third from 1989 to 2015. The rate of afforestation from 2000 to 2015 was 4 times the rate observed between 1989 and 2000. A trend toward gradual afforestation of higher-elevation and gentler-slope areas and land relief and terrain niche zones was observed between the 2 periods. Expansion mostly occurred in grasslands, arable lands, and unused lands. Elevation, slope, and land relief were the dominant topographic factors influencing forest cover change. Such factors influenced afforestation directly through their effect on microclimates and local biophysical conditions and indirectly by limiting the geographic area where forest programs could be implemented. Terrain niche was also an important predictor of forest cover change under complex topographic conditions. The GWR results indicate heterogeneous forest cover change processes across the study area. Our analysis could guide the implementation of effective forest expansion programs and policies, particularly for degraded mountain ecosystems.

Labor migration and the decoupling of the crop-livestock system in a rural mountainous area: Evidence from Chongqing, China

Massive out-migration of rural labor force brings both challenges and opportunities to crop-livestock integrated production system (crop-livestock system) in smallholder economy. Compared with previous researches that have paid major attention to the effect of labor migration on either crop production or livestock husbandry, this study considers the mediating role of crop production in predicting the effect of labor migration on livestock raising. Our econometric estimation based on a 2012 survey of 974 rural households in Chongqing, a mountainous region of China, showed the following. (1) The massive migration of rural labor force had led to significant increase in farmland abandonment and considerable changes in the pattern of livestock raising. (2) The livestock raising number per household began to differentiate, with the livestock system separating from the traditional crop-livestock system and becoming a specialized business. (3) In terms of the pathways through which rural labor migration exerts impact on livestock raising number, though the increased opportunity costs of rural labor greatly reduced farmers’ willingness to raise livestock, the decoupling of the crop-livestock system partly alleviated the declining trend in the livestock raising number because of the availability of household labor force freed from cropping via farmland abandonment. These findings have important policy implications for rural development and agricultural restructuring in mountainous areas of China, and provide references for other developing countries.

A review and prospects of debris flow waste-shoal land use in typical debris flow areas, China

The shortage of land resources is one of the most pressing policy challenges faced by China, where many attempts have been made to increase the quantity and quality of land available for human use while protecting the environment. In the regard, the use of debris flow waste-shoal land (DFWSL) has achieved success. Although DFWSL is being developed and used, it has not yet received sufficient attention, and many challenges remain in the process of utilization. In order to improve awareness regarding DFWSL use and identify the opportunities and challenges, we evaluated the current policies and practices guiding the use and management of DFWSL in China using a combination of literature review and field studies. The results show that DFWSL development in China can be classified into three main stages: initial (risk assessment), development (analysis of soil properties and production potential), and mature (efficient and safe use). Ongoing research has placed increasing attention on the coordinated development of economic and ecological security, but some problems remain. First, the geomorphic nature of DFWSL is not always clearly recognized, leading to utilization that does not follow best practices. Second, the current theoretical system for development is insufficient, presenting barriers to scientifically informed and rational utilization. Third, there is a lack of clear and comprehensive policy guidance from the government. Therefore, we propose a new conceptual framework for DFWSL development that emphasizes a landscape-friendly trajectory that balances economic development and security. We expect this study to increase the focus on development in mountainous regions of China and encourage further investigation of the marginal land use potential in ecologically fragile areas where debris flows frequently occur.

Spatial variation in morphology of the White-browed Laughingthrush (Garrulax sannio) and its relationship with climate conditions in southern China

Geographic heterogeneity and climatic conditions are credited for shaping contemporary patterns of avian biodiversity as populations respond differently to landscape-level changes in the environment. Southern China is a globally recognized region characterized by geographic heterogeneity and avian diversity. We analyzed geographic variation in the morphology of the White-browed Laughingthrush (Garrulax sannio) throughout southern China, and examined the relationship between spatial morphological variation and current climate conditions. White-browed Laughingthrushes in the southwest mountain region of China were characterized by larger body component and foraging components, but smaller maneuverability component in relation to their eastern or northeastern conspecifics. The annual temperature component was correlated positively with foraging component, but negatively with maneuverability component and skull length. Wet season precipitation was correlated positively with maneuverability, but negatively with cranial component. These results suggest the local adaptation of G. sannio with climate conditions in southern China and provide a better understanding of the factors shaping contemporary biogeographic patterns of avian morphology, allowing for the prediction of potential responses of species to future climate changes.

Influence of the pier heights on the seismic response of large rigid frame bridges in mountain regions

In recent years, several large rigid frame bridges with piers over 100 meters have been built in mountain regions in China. However, few studies are focused on the influence of the height of piers on the seismic performance of these bridges. Based on the sizes of piers of the existing large continuous rigid frame bridge in the world, finite element models with different pier heights of the bridges are established and dynamic analysis are conducted subjected to three-dimensional multi-support excitation. The seismic response of the structures is studied with the change of pier heights and natural periods. The results show that in actual engineering designs, it is strongly recommended that the adjacent piers with similar heights or very different heights should be avoided. The conclusion also provides suggestion to the design of large rigid frame bridges afterwards.

AI-based identification of low-frequency debris flow catchments in the Bailong River basin, China

Debris flow is a major geohazard in mountainous regions and poses a significant threat to life and property. The damage caused by debris flows have increased with the expansion of human settlements and activity into the mountainous regions of China. In regards to risks from debris flows, previously unrecognized low-frequency debris flow catchments constitute an especially significant threat. According to our investigation, only about 500 catchments have debris flow records in >2000 catchments of Bailong River basin. The main purpose of this paper is to introduce a new methodology using Artificial Intelligence (AI) that can simultaneously input parameters related to geomorphological conditions and material conditions to better distinguish low-frequency debris flow catchments (LFDs) from medium-high frequency debris flow catchments (MHFDs). A total of 449 prototypical debris flow catchments, 15 parameters, and 9 commonly used learning machines were used to build identification models. Debris flow catchments are divided into 4 cases (LO1-LO4) based on different sample ratios of LFDs and MHFDs, which are input into each classifier one by one. Based on model evaluation, the CHAID model in the case LO2 performs best, which only uses five parameters (formation lithology index, land use index, vegetation coverage index, drainage density and landslide density index) to predict LFDs. The results indicate that LFDs are mainly distributed in areas with less landslide distribution and better vegetation coverage compared with MHFDs. However, the distribution of LFDs is concentrated on FLI (formation lithology index) =4, which is the weak lithology area. The tree classifier seems to be better at classifying fluvial processes. The model developed in this paper can help us quickly find LFDs in similar areas, and help to assess the risk of debris flows.

Geohazards, reflection and challenges in Mountain tunnel construction of China: a data collection from 2002 to 2018

In face of the complicated and changing geological conditions, safety issue is always a primary concern during the construction phase of tunnel in the mountainous regions of China. This Express Letter reports data collection concerning the geo-hazardous events recorded in tunnel system in the period from 2002 to 2018. These accidents include collapse, water inrush, gas explosion, portal landslide, suffocation and avalanche. A total of 97 geohazard events resulted in 393 deaths, 467 injuries and 51 missing. Statistical results indicate that collapse is the primary geohazard in mountain tunnel construction. The data confirmed a high correlation between the number of casualties and geohazard accidents quantity. It is also observed that water inrush is more likely to happen in karst region, while the collapse is mainly recorded in loess and karst areas. During the period under the review, the data illustrates an overall decrease of casualties and geohazard events, but it still faces a grim situation regarding the geohazard prevention in mountain tunnels construction of China. Hence, countermeasures and future research attempts focusing on geohazards prevention and mitigation are recommended.