Mountain City Research Articles

The optimization of the "UAV-vehicle" joint delivery route considering mountainous cities.

As a new transportation tool, unmanned aerial vehicle (UAV), has a broad application prospect in logistics distribution, especially for mountainous cities with complex terrain. Due to the limited delivery conditions of UAV, considering the advantages of traditional vehicle delivery, this paper proposes a joint delivery mode of UAV and vehicle, and designs three steps for the joint delivery problem of single UAV and single vehicle: first, mark all special nodes; Secondly, the route of UAV and vehicle is planned; Finally, the total delivery route is optimized to minimize the total delivery distance. Genetic algorithm and single distribution terminal optimization are used to solve the problem, and the joint delivery in this paper is compared with the traditional vehicle delivery and the independent delivery of UAV and vehicle. The results show that UAV and vehicle can cooperate with each other to complete the delivery of all customer demand nodes, and the joint delivery of UAV and vehicle can effectively reduce the total delivery distance. Finally, the sensitivity analysis of UAV’s maximum load, maximum flight distance, relative speed between UAV and vehicle, and road impedance coefficient is carried out. By relaxing the restrictions of UAV, the UAV can deliver more customers at a single time, and it complete the delivery task with vehicles efficiently.

A Route Choice Model for Road Network Users in Mountainous Cities considering Vulnerability

Urban resilience has become one of the core arguments of sustainable urban development. The urban road system should also respond effectively to various changes or impacts and reduce the uncertainty and vulnerability of road network caused by emergencies. A route choice model considering the vulnerability was proposed. The model analyzed the traveler’ behavior in complex road network. The model is validated by the road network in Chongqing city. First, the vulnerability of road network in mountainous cities is defined, and the failure situation and state classification of road network considering vulnerability are analyzed. The results show that travelers with different sensitive states have obvious different route choice behavior in vulnerable networks. Since nonsensitive users do not reserve travel time in the early days, they are more inclined to respond to emergencies quickly and then choose fast detour paths. However, sensitive users have set off earlier than normal time and have psychological expectations of emergencies. They have more time to maintain the existing path. Finally, a calculation example is used to test that a certain section of the road network fails randomly, and network users can effectively choose the individual optimal route under different failure states.

Spatial Distribution and Influential Factors of Nutrients in Rivers of a Typical Mountainous City: A Case Study of the Qingshuixi River in Chongqing

Surface water pollution seriously restricts the development of the city and results in the citizens yearning for a better life. Mountainous cities have their own characteristics in surface water environment and pollution compared with those of plain cities due to their unique topography. In August and October 2019, surface water and sediments were collected in a typical river (Qingshuixi River) in the main urban area of Chongqing. These samples were analyzed for nutrients such as carbon, nitrogen, and phosphorus as well as other basic physicochemical indicators. The results showed that the surface water of the Qingshuixi River was inferior to Category V at present, and it was also at a serious pollution level according to the comprehensive pollution index evaluation system. Among all the water quality indices, NH4+ and TP showed the most serious pollution. The tributaries of the Qingshuixi River exhibited higher surface water quality than that of the main stream, and the water quality during the rainfall season was better than that during the non-rainy season. Pollution sources, tailwater/tributary inflow, and river self-purification capacity determined the spatial distribution of nutrients in the surface water of the mainstream of the Qingshuixi River. Point sources such as the direct discharge of source sewage and pollution overflow in the middle and lower reaches were the most important sources of surface water pollution in the mainstream of the Qingshuixi River. Non-point source pollution had a limited impact on water quality. The "sink" or "source" role transformation of river sediments would occur under different water volume conditions in the river, reflecting the complexity of endogenous pollution. Surface water quality of the main stream showed a gradual improvement tendency along the downstream due to the dilution of the tail water/tributary inflow and the increased self-purification capability of the surface water in the mountainous rivers due to the increased DO content. To summarize, this study suggests that the water environment of the Qingshuixi River should be improved in comprehensive ways, which might be reducing the input of point source pollution by the deployment of the municipal pipe network in key areas, upgrading the sewage treatment plants to decrease pollutant concentrations or fluxes or channel dredging at the reaches with low DO content, etc.

Three-dimensional high-precision assessment of mountainous urban underground space resources: A case study in Chongqing, China

Urban underground space resource (UUSR) assessment can facilitate the planning of underground space development and utilization in highly populated urban areas. Typically, UUSR assessment involves dividing the assessment area, determining the assessment index, establishing the assessment model, integrating the assessment data, and calculating the results. A method for streamlining the three-dimensional (3D) high-precision UUSR assessment process was proposed, aiming at the mountainous cities. Assessment indexes suitable for the mountainous UUSR were determined, and a variable weighting model was constructed to enhance the credibility of the assessment results. Multi-source assessment data were compressed and stored using a chain run-length encoding data structure, which can be queried to obtain the attributes of the assessment cells. In addition, a 3D assessment system was developed to automate the assessment process using distributed computing. Finally, taking Chongqing City as a case study, the assessment was conducted over a surface area of approximately 19.4 km2 and to a depth of 50 m. The study area was divided into 9.72 × 108 assessment cells, with the dimension of 1 m × 1 m × 1 m. The results show that the 3D high-precision UUSR assessment successfully reported the construction risks at the urban scale. The construction risks of a 15-km underground rail transit line can be analyzed, thereby providing decision-making support for underground space development and transit line layout.

Progressive Collapse of the Base-Isolated Frame Structures Supported by Stepped Foundation in Mountainous City

Base-isolated frames supported by stepped foundation in mountainous areas possess their own particularity, so its progressive collapse dynamic response performance and dynamic effect propagation path are very different from those of ordinary flat ground-isolated structural systems. In order to study the progressive collapse performance of the base-isolated frames supported by stepped foundation in mountainous areas under two-directional coupled dynamic excitation, a four-span three-story plane frame demolition column test was simulated to verify the reliability of the computing platform. The common ground motion and three types of long-period ground motions were selected, and the two-dimensional dynamic coupling of the ordinary flat ground isolation structure and the base-isolated frames supported by stepped foundation in mountainous areas was obtained based on the demolition method. First, the seismic isolation structure was subjected to the collapse dynamic response under the vertical unbalanced load, then the collapse dynamic response under the vertical unbalanced load and the horizontal seismic coupling excitation was made; the two were compared and analyzed. It can be used as a reference for the design of progressive collapse of the frame structure of the base-isolated frames supported by stepped foundation in mountainous areas.

Research on urban spatial structure based on the dual constraints of geographic environment and POI big data

A large number of cities in China have proposed the spatial development strategy of polycentric in their planning, but whether the evolution of polycentric structure meets the planning expectation and whether the polycentric structure and function can be identified through effective ways has become a hot topic of academic research at present. Compared with the traditional survey and identification methods of population, land use and industry, the emergence of urban big data provides an opportunity for polycentric identification, especially the analysis based on POI (Point of Interest) big data is more accurate and efficient than the traditional methods. Chongqing, as a typical representative of mountainous cities, has chosen the development model of polycentric clusters at an early stage and strengthened it in the planning, forming a real polycentric city with both form and function, which makes it typical and representative among polycentric cities in China. Based on the POI data of Chongqing's main urban area, the paper identifies the polycentric structure of the city as a whole and different functions and its influence range based on the spatial distribution characteristics and aggregation degree of the overall and different types of POI data. The results show that Chongqing, as a mountainous city, exhibits an obvious “polycentric and clustered” structure under natural constraints and planning guidance. The study of Chongqing can reveal the differences between the polycentric characteristics of mountain cities and plain cities, summarize the effectiveness and shortcomings of polycentric development, and provide useful reference for urban planning. This paper collects all kinds of geospatial data, network big data and all kinds of historical statistical yearbook data in the main urban area of Chongqing. The experimental results show that by using the double constraints of POI big data and geographical environment, Chongqing is in urban polycentric structure, different functional types of urban centers, and employment function space and leisure and recreation function space have many advantages.

How Urban Fringe Expansion Affects Green Habitat Diversity? Analysis from Urban and Local Scale in Hilly City.

Hilly cities in China have gone through an extensive expansion, and urban fringe morphology has experienced a massive change. As a result, green habitats have been occupied or disturbed, and such landscape changes can impact biodiversity. Understanding how urbanization impacts green habitats is essential for urban sustainable development. However, such understanding is lacking for hilly city. This study has two objectives: (1) to quantify the spatiotemporal patterns of green habitats in hilly city fringe during 2000-2020; (2) to identify the differentiated impacts of different hilly city expansion shapes on green habitat. By using landscape indexes to characterize green habitat patterns, the green habitats impact analysis was processed in two scales, at urban scale and local scale. Information Entropy Model and Classification and Green Habitat Quality Evaluation were used to reveal the relationships of urban expansion shapes and green habitat quality in mountainous city. The results showed that, at urban scale, (1) the more complex the city fringe morphology is, the more negative impacts there are on green habitats, (2) and when Guiyang urban fringe green space declined, the green habitats type pattern was refactored. At the local scale, we classified urban fringe expansion into four shape styles; we then discussed the changes of green habitats from the perspective of shape style and stage of urbanization. The results showed that, (1) dispersed type and strip type of urban fringe expansion led to the largest green habitat lost, besides, spreading type and strip type resulted in the largest loss of green habitats core areas. (2) Moreover, at a different stage of urban fringe expansion, the challenge of green habitats persistence was varied, the legacy type has been eager for special species habitats. However, the new type has been facing the risks of guaranteeing habitats stock and quality.

Landscape Visual Aesthetics Measurement, Assessment, and Improvement of Street Pedestrian Spaces in Mountainous Cities—Case Study on the Historic Downtown of Jinan, Shandong Province

Landscape Visual Aesthetics Measurement, Assessment, and Improvement of Street Pedestrian Spaces in Mountainous Cities—Case Study on the Historic Downtown of Jinan, Shandong Province

Revealing Interactions between Polycentricity and Commuting Costs in a Mountainous City

Revealing Interactions between Polycentricity and Commuting Costs in a Mountainous City

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

基于形态学空间格局和空间主成分的贵阳市中心城区生态网络构建

PDF HTML阅读 XML下载 导出引用 引用提醒 基于形态学空间格局和空间主成分的贵阳市中心城区生态网络构建 DOI: 10.5846/stxb202012213241 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（32060367）；贵州省科学技术基金重点项目（黔科合基础[2020]1Z011）；贵州省科技支撑计划项目（黔科合支撑[2021]一般458） Construction of ecological network in downtown of Guiyang city based on morphologically spatial pattern and spatially principal component analysis 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:喀斯特多山地区，城市扩展过程中大量自然山体镶嵌入城，形成具有多种生态系统服务功能的城市遗存自然山体。但在城市内部致密化发展过程中，这些城市遗存山体常被城市建设用地孤立和包围，形成人工干扰场中的生态孤岛。生态网络的构建既有利于城市遗存自然山体自然资源保护，又有助于丰富城市绿色基础设施生态系统服务功能。以喀斯特地区典型的多山城市——贵阳市行政区为研究对象，综合利用形态学空间格局分析法和景观连通性识别中心城区生态源地，基于主成分分析确定研究区综合阻力面，通过最小累积阻力模型、重力模型和水文分析等方法，识别并优化关键衔接廊道及节点，在中心城区行政区和建成区两个尺度构建研究区生态网络。结果表明：（1）行政区生态源地分布整体呈现"南北相望"的格局，建成区生态源地集中在中部；（2）研究区综合生态阻力高值主要集中在研究区中部，呈放射状向外扩散，综合生态阻力低值主要分布在研究区周边，以大型林地斑块为主；（3）行政区极重要、重要、一般廊道数分别为15、21、69，极重要廊道集中分布在北部，建成区极重要、重要、一般廊道数分别为37、113、227条，极重要廊道主要分布在建成区中部；（4）行政区和建成区一类生态节点分别为29、25个，二类生态节点33、17个。最终通过叠加行政区和建成区生态网络要素，形成贵阳市中心城区生态网络，研究结果能为贵阳市中心城区在未来用地空间上协调生态保护与城市发展提供科学合理的参考。 Abstract:In the karst mountainous area, with the urban expansion, a large number of natural mountains have been embedded into the urban built-up area, forming the urban remnant natural mountains which have various ecosystem service functions. However, in the process of dense development within the urban area, these urban remnant mountains were often isolated and surrounded by the urban construction land, forming the ecological islands in the artificial interference field of urban built-up area. Construction of ecological network of the mountainous urban could be not only conducive to the protection of natural resources of urban remnant natural mountains, but also beneficial to enrich the service functions of urban green infrastructure ecosystem. Taking the downtown of Guiyang, a typical mountainous city in karst area, as research area, we comprehensively used morphologically spatial pattern analysis (MSPA) and landscape connectivity to identify ecological sources and determined the comprehensive resistance area based on the principal component analysis. We also identified and optimized the key connection corridors and nodes through the minimum cumulative resistance model (MCR), and constructed the ecological network at two scales of the administrative area and the built-up area of the research area. The results showed that:1) the overall distribution of ecological sources in the administrative region presented a pattern of "north and south facing each other", and the ecological sources in the built-up area were concentrated in the central part; 2) The high values of comprehensive ecological resistance were mainly concentrated in the middle of the study area and radially spread outwards, while the low values were mostly distributed in the periphery of the study area with large forest patches; 3) The number of essential, important and general corridors in the administrative region were 15, 21 and 69 respectively. The essential corridors were concentrated in the north of the study area, meanwhile, the number of essential, important and general corridors in the built-up area were 37, 113 and 227 respectively, and the essential corridors were mainly distributed in the middle of the built-up area; 4) There were 29 and 25 ecological nodes in the administrative and built-up areas, and 33 and 17 second-class ecological nodes, respectively. Finally, by superposition the ecological network elements of administrative region and built-up areas, the ecological network of the downtown of Guiyang City was constructed. This study could provide scientific and reasonable reference for coordinating ecological conservation and urban development in the central urban area of Guiyang city. 参考文献 相似文献 引证文献

城市基质对城市遗存自然山体植物群落物种多样性的影响--以贵阳市为例

PDF HTML阅读 XML下载 导出引用 引用提醒 城市基质对城市遗存自然山体植物群落物种多样性的影响--以贵阳市为例 DOI: 10.5846/stxb202101070069 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(32060367)；贵州省科学技术基金重点项目(黔科合基础[2020]1Z011)；贵州省科技支撑项目(黔科合支撑[2021]一般458) Exploring the relationship between the plant diversity of the urban remnant mountains and its surrounding urban matrix characteristics：A case study of Guiyang City 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:多山地区城市扩展过程中,建成区内遗存有大量自然山体,形成城市人工基质"海"中的遗存山体"岛屿生境",这些城市遗存山体长期受到来自城市人工环境的各种间接或直接的干扰。为探索城市基质与城市遗存自然山体植物群落多样性之间的关系,以黔中地区典型的喀斯特多山城市--贵阳为研究区域,按不同规模选择15座城市遗存山体,每座样山按坡向+坡位组合方式设置群落调查样地,共设置143个样地;以样山边界为基准,100 m为步长向外设置20个缓冲区,总宽度为2000 m,计算缓冲区总不透水表面积(PTIA)、植被覆盖度(VC)、破碎化指数(FI)、土地利用(LU)4个城市基质特征指标。运用Pearson相关分析和线性回归模型分析了城市基质特征指标与城市遗存山体植物群落物种多样性之间的相关关系。结果表明:①PTIA对不同规模城市遗存山体整体植物多样性的影响都存在明显空间尺度效应,在2000 m时相关性最高,呈显著正相关;不同规模城市遗存山体整体植物多样性与单个或多个LU类型存在显著相关性,但影响效应存在显著差异;VC、FI与城市遗存山体整体植物多样性无显著相关关系;②不同规模城市遗存山体各层次植物多样性与城市基质特征 4个指标在不同的空间尺度上均存在显著相关性;③城市遗存山体植物多样性Shannon-Wiener指数(H')与每个城市基质特征指标一元线性回归拟合度高,而多元回归R2为0。探明城市基质特征对城市遗存山体植物多样性具有一定的影响,但影响规律不一致且存在空间尺度差异,说明城市人工环境对城市遗存山体植物多样性维持的影响非常复杂,需要从不同的角度开展深入的研究,才有可能揭示城市遗存山体植物多样性的城市化响应机制,进而指导城市遗存山体保护规划与管理。 Abstract:In the process of urban expansion in mountainous areas, there are a large number of natural mountains remained in the urban built-up area, forming the urban remnant mountain "island habitat" in the urban artificial matrix "sea". These urban remnant mountains (URMs) have long been affected by a variety of indirect or direct interference from the urban artificial environment. To explore the relationship between the plant diversity of the URMs and its surrounding urban matrix characteristics, taking the urban built-up area of Guiyang, a typical karst mountainous city in central Guizhou, as the research area, fifteen URMs were selected according to different sizes as research objects in this study. The sample spots of each URM were set by the combination way of slope direction and slope position. A total of 143 plant diversity survey plots were set up on the fifteen URMs. Taking the edge line of sample URMs as datum, buffer zones were set successively outward at step lengths of 100 m and 20 buffer zones were set with a total width of 2000 m. The proportion of total impervious surface area (PTIA), vegetation coverage (VC), fragmentation index (FI) and land use (LU) of each zone were calculated. The correlation between the urban matrix characteristic indices and the species diversity indices of the URMs plant communities was analyzed using the Pearson correlation analysis and the linear regression model. The results showed that: (i) the influence of PTIA on the overall plant diversity of different size URMs had obviously spatial scale effects, with the highest correlation and significantly positive correlation at 2000 m; The overall plant diversity of different size URMs were significantly associated with a single or multiple LU types, but the impact effects were significantly different; There was no significant relationship between VC and FI and the overall plant diversity of URMs. (ii) The plant diversity indices of all plant levels of different size URMS were correlated with the four indices of urban matrix characteristics at different spatial scales. (iii) The Shannon-Wiener index (H') had a high linear regression fit to each urban matrix index, however the multiple regression R2 was 0. In this study, it was explored that the urban matrix characteristics had some influence on the plant diversity of URMs in different scales, but the influence laws were inconsistent. It shows that the impact of urban artificial environment on the maintenance of plant diversity of URMs is very complex. It is very necessary to conduct in-depth research from different perspectives to reveal the urbanization response mechanism of plant diversity of URMs, and then guide the protection planning and management of URMs. 参考文献 相似文献 引证文献

Relationship between construction land and slope in rapidly expanding mountain cities: A case study in Guiyang, China

Relationship between construction land and slope in rapidly expanding mountain cities: A case study in Guiyang, China

Street-level solar radiation mapping and patterns profiling using Baidu Street View images

• Street-level solar radiation mapping and patterns profiling with Baidu Street View (BSV) images are studied. • A BSV-based radiation estimation method considering weather conditions is established to map the hourly street-level solar radiation. • A two-stage clustering method is proposed to profile the solar radiation patterns. • Eight types of daily radiation patterns and six types of multifaceted radiation patterns are discovered. • Maps of street-level solar radiation can provide useful datasets for urban study. The variability of urban landscapes and weather conditions makes it challenging to quantify the solar radiation of urban streets. In this study, we propose a framework to map and profile the street-level solar radiation using Baidu Street View (BSV) images. In our framework, a BSV-based radiation estimation method considering weather conditions is established to map the hourly street-level solar radiation. Then, a two-stage clustering method is proposed to profile the radiation patterns, including daily radiation patterns (DRP) and multifaceted radiation patterns (MRP), from the estimated radiation data. Taking Chongqing as a case, results show that (1) the estimated solar radiation of the proposed method is closer to the real situation than the two existing methods. (2) The solar radiation of streets varies greatly among different road grades and streetscapes; the street environment and weather conditions have a significant impact on solar radiation in mountain cities. (3) Eight types of DRP and six types of MRP are discovered by the two-stage clustering method. Moreover, the features, geographical distribution and applications of the radiation patterns are investigated in detail to support urban planning. This work can greatly promote studies relating the solar radiation at the street-level in the future.

Spatial-temporal characteristics of particulate matters and different formation mechanisms of four typical haze cases in a mountain city

The mechanisms by which pollution forms and acts in mountain cities are unique and remain unclear owing to terrain and meteorological conditions in the mountains. This study investigates the pollution characteristics in Chongqing, a typical mountain city, over the period from 2013 to 2017. Routine observed surface meteorological data, CALIPSO data, ERA5 reanalysis data and the backward trajectory calculation were used for analysis and comparison among four typical pollution cases. The results can be summarized as follows: (1) Pollutants in firework and unfavorable weather condition case mainly originated from local emissions. Anthropogenic aerosols that were characterized by spherical and small particles were detected, which contributed to the higher atmospheric scattering ability. Meanwhile, high humidity was beneficial to hygroscopic growth, resulting in a mixture of haze and fog forming low-visibility conditions. The strong inversion of the upper-layer and the presence of high mountains meant that local pollutants became confined within the basin region, leading to the formation and maintenance of pollution. The important roles of the weather conditions that are associated with mountains, such as cold air damming, low-level jet, valley and gap wind, were also revealed by the variable pollution conditions. (2) Airflow originating from Guizhou, Guangxi, and Hunan, where numerous fire points were detected, transported pollutants that were released from straw burning through upper-lower layer transport to the basin during the straw burning case. The aerosols detected showed low depolarization but a high color ratio, which are the typical characteristics of smoke. The inversion layer did not cover the entire basin, indicating that smoke aerosols were transported by downdraft to mix with local pollutants. (3) During the dust case, large amounts of dust aerosols were detected reaching from the surface to the troposphere, with a special double-layer structure. A lower depolarization ratio but stronger scattering ability was observed for the dust aerosols above the study region, which was attributed to mixing with other aerosols and chemical processes. Secondary circulation occurred when the inversion layer was at around 700 hPa, bringing dust aerosols from around 850 hPa to the surface. This study provides an understanding of the optical properties of the various types of aerosols and highlights the importance of weather condition in the formation and maintenance of pollution events. The results emphasize the need for intense vertical measurement in mountain cities.

Analysis of the behavior of lightning activity and its meteorological variables in mountain cities. Case of Manizales, Colombia

El presente artículo muestra el comportamiento diurno y estacional de la actividad de rayos y su relación con las variables meteorológicas que intervienen en la formación de las tormentas, en una ciudad de montaña. Los resultados muestran que Manizales tiene en promedio 69 días tormentosos, es decir, son los días donde al menos un rayo es detectado. Dentro de los resultados, también se puede apreciar que los meses con mayor actividad son marzo y noviembre. El análisis se realizó para los dos periodos lluvioso y seco que se presentan en la zona andina de Colombia. Los resultados muestran que durante los periodos de lluvia la actividad de rayos es más intensa y que obedece principalmente a vientos locales y al desplazamiento de la Zona de Confluencia Intertropical. Dentro del análisis de las variables meteorológicas fue utilizado el ciclo diurno promedio para observar el comportamiento de estas durante los días con actividad de rayos y los que no tuvieron actividad, las variables analizadas fueron presión de superficie, temperatura superficial del aire, temperatura de punto de rocío, razón de mezcla, vientos zonal y meridional.

Combined impacts of the abnormal and urban heat island effect in Guiyang, a typical Karst Mountain City in China

The abnormal heat island (AHI) effect has recently been reported in several karst cities. However, the combined effect of the abnormal and urban heat island (UHI) effect is still a gap. This study analyzed the combined effect the AHI and UHI in Guiyang, a typical rapidly urbanizing karst mountain city, to provide insights into the variation and formation of AHIs and UHIs using Landsat imagery. Although the AHI effect remained the major component of the thermal environment, the impact of UHI intensified with rapid urbanization. Moreover, in addition to suitable topographic conditions such as shallow slopes and high elevations in sunny aspects, the low and low-medium vegetation coverage lands were highly related to the formation of the AHI, and the AHI intensity increased in almost all directions with urban expansion. In addition, the formation conditions and mechanism of the AHI can be attributed to the unique thermal properties of karst carbonate. The above results suggest that karst rock desertification is the key point for the improvement of the regional thermal environment, so comprehensive prevention of rock desertification and rational planning of construction projects should be involved in environmental protection in karst mountain cities.

Exploration on Landscape Reconstruction Design of Old Residential Communities Embedded with Green Technology Based on Smoke-Free Environment: Regarding Shangdatianwan Central District in Yuzhong District of Chongqing a Case

A smoke-free environment is crucial to the health of low-income, marginalized and vulnerable groups in the wake of COVID-19 and extreme weather. Low-income vulnerable groups mostly live in old residential areas, where the quality of living environment is poor. Ground buildings lack fire protection and smokeless facilities, and ground, rain and sewage pipes are mixed, posing serious safety and health risks. However, urban reconstruction and restoration often pay attention to the smoke-free environment, underground pipe network facilities and green and intelligent application of new residential areas, while ignoring the implantation of smoke-free environment, environmental protection and energy saving sustainable technology measures in the reconstruction of old residential areas. The old residential areas are the last link in the implementation of smoke-free policy and the most vulnerable areas of urban governance. Urban renewal design implanting smoke-free environment and green technology into urban fabric can improve its resilience and quality of living environment. Based on this, taking Shangdayanwan Central District, Yuzhong District of Chongqing, a typical mountain city, as an example, the reconstruction and design of the old residential area with green technology embedded in smoke-free environment was carried out, and the technical mechanism was explored, providing reference for urban renewal design to reduce pollution, prevent disasters and improve the ecological conservation of human settlements.

Remote Sensing Characterization of Mountain Excavation and City Construction in Loess Plateau

AbstractThe demand for land exploitation to accommodate increasing population in metropolis is escalating worldwide. The unprecedented Mountain Excavation and City Construction project in the hilly gully Loess Plateau of China is a crustal surgery to seek the balance between urbanization and sustainability in the forerunner Yan'an city. Here, we rely on multisource remote sensing imagery to characterize the contemporary anthropogenic modification of the loess landscape. The topography has been reshaped with ±80‐m elevation changes and 1.28 × 108‐m3 mass transfer by 2015. The subsidence rates at up to ∼70 mm/year during 2014–2020 are proportional to the amount of the filling mass, which is expected to reach stabilization by 2030. Hundreds‐of‐kilopascal stress changes are distributed in the shallow zone due to the mass transfer. Continuous monitoring is an integral part of hazard mitigation in this naturally landslide hazard‐prone loess environment.

Assessment of Ecosystem Service Supply, Demand, and Balance of Urban Green Spaces in a Typical Mountainous City: A Case Study on Chongqing, China.

Objective measurement of the supply–demand of ecosystem services (ESs) has received increasing attention from recent studies. It reflects the relationship between green spaces and human society. However, these studies rarely assess the mountainous cities. To fill this gap, this study takes a typical mountainous city as a research case to reveal the supply–demand relationship of ecosystem services, then development and management strategies are proposed for different districts according to their spatial differentiation characteristics. Results shows that: (1) there are differences of ESs supply between each district, and supply from Banan District is significantly higher than others. (2) The demands for ES also vary widely, which are higher in the core urban areas. (3) There are different degrees of imbalance between supply and demand in each district. We classified green spaces into four types based on their supply–demand characteristics, and optimization strategies are proposed. We found that most of the districts are lack of ES supply while there is a relatively high demand for ES in Chongqing, and the balance of supply and demand between different districts varies greatly. Our study indicates that targeted urban green spaces strategies for different districts must be considered to adequately optimize ES in mountainous cities.