Dynamic assessment and early warning of ecological security: a case study of the Yangtze river urban agglomeration

Natural Hazards - Ecological security is vital to the survival of human beings and critical to the sustainable development of socioeconomic environment. In view of the deficiencies of the static...     

城市化过程中都市农业景观变化及其生态安全评价——以西安市为例

快速城市化过程中都市农业景观变化及其生态安全研究是城市化区域生态安全和可持续发展研究的重要课题.构建都市农业景观生态安全评价指标与方法,探讨城市化对都市农业景观生态安全的影响具有重要的科学意义.以西安市为例,应用GIS和RS技术方法,结合"压力-状态-响应"(PSR)模型建立了都市农业景观生态安全综合评价指标体系,通过提取1999、2006和2013年的农业景观类型信息,定量分析了都市农业景观变化特征、动态评价了都市农业景观生态安全过程.结果表明:1999-2013年西安市农业景观结构变化剧烈,景观斑块数量增加、平均斑块面积减小,聚集度变差,景观趋于复杂化、破碎化,耕地、林地面积显著减少,园地面积增加.城市化的快速发展导致都市农业生态安全压力指数由0.43上升为0.59,生态安全状态指数由0.73降至0.28,生态安全响应指数则由0.26上升为0.77,生态系统服务价值下降;城市化过程带来的景观压力指数上升以及景观状态指数下降,使得都市农业景观生态安全综合指数由0.56先下降为0.4,后上升到0.48.城市化过程中的都市农业景观生态安全评价可以为都市农业可持续发展、土地可持续利用管理和科学决策提供依据.     

Climate change and the future of freshwater resources of the island: a case study on the Rishiri Island,Japan

A comparison of the d-excess values of precipitation and of spring water, streams, groundwater wells and submarine groundwater discharge indicated that the precipitation that occurred during winter season was an important source of groundwater recharge. Due to the steep slope of the island, most of the short duration and high intensity precipitation is lost through direct surface runoff. The comparison indicated that snowmelt is an important resource of groundwater recharge on Rishiri Island. Future climate change will continue to diminish the snowpack, and therefore, reduce groundwater recharge. It may cause the decline of the groundwater level in the coastal area and possibly shift the saline–freshwater boundary on the island. Chloride data indicated that saltwater intrusion is beginning to occur on the western flank of the island. A Piper diagram shows that the water samples are characterized by the dominance of the Ca–HCO₃ and Na–Cl type. Their chemistry probably results from sea salt spray and the dissolution of minerals. These results support the need for the effective management of groundwater resources.     

Modeling the influence of urbanization on urban pluvial flooding: a scenario-based case study in Shanghai,China

Natural Hazards - Rapid urbanization has brought great productivity, prosperity and challenges to Shanghai in the last few decades. This paper focuses on the influence of urbanization on urban...     

Boundary assessment under uncertainty: A case study

Estimating certain attributes within a geological body whose exact boundary is not known presents problems because of the lack of information. Estimation may result in values that are inadmissible from a geological point of view, especially with attributes which necessarily must be zero outside the boundary, such as the thickness of the oil column outside a reservoir. A simple but effective way to define the boundary is to use indicator kriging in two steps, the first for the purpose of extrapolating control points outside the body, the second to obtain a weighting function which expresses the uncertainty attached to estimations obtained in the boundary region.     

Cellular automata-based model for developing land use ecological security patterns in semi-arid areas: a case study of Ordos, Inner Mongolia, China

The semi-arid areas in Northern China are home to a large population and have great ecological vulnerability. Contemporary land use pressures cause these areas to suffer from a severe land use conflict between human activities and environmental conservation. Ignoring the livelihood of humans and the development of semi-arid areas is not possible. However, the rapid increase in human activity recently exposes both the human race and local environment to potential adverse effects. To balance this contradiction, this research puts forth a framework to optimize the land use patterns in these areas in the context of ecological security and land use suitability. Considering the expansion of particular land use forms to meet the land use demand of social development, a revised cellular automata model is employed to shape the path of land expansion. Meanwhile, additional adjustment rules are set to adjust the unreasonable land use units to a suitable form. The city of Ordos is chosen as a case to put this framework into practice, and several landscape pattern indexes are used to evaluate the results. The results reveal that this framework could maintain the environment in a stable state while simultaneously meeting the land use demand of social development.     

Modifications in vegetation cover and surface albedo during rapid urbanization: a case study from South China

The green vegetation fraction (GVF) and surface albedo are important land surface parameters often used for validation of climate and land surface models that are influenced largely by environmental gradients and human activities. In this study, fine resolution GVF and albedo values derived from Landsat Thematic Mapper/Enhanced Thematic Mapper Plus images from 1990 to 2000 were used to examine the relationship of both GVF and albedo values to the spatial gradients of parameters related to dramatic urbanization in the Greater Guangzhou metropolitan area, Guangdong Province, in South China. Moderate resolution GVF and albedo datasets derived from the MODIS Collection 5 product were used to analyze the seasonal variation of GVF and albedo with rapid urban expansion from 2001 to 2007. The results show that the shortwave albedo had a clear declining trend from the urban center to natural land in 1990. However, no obvious trend in shortwave albedo change was observed along urban–rural gradients caused by the expansion of low-albedo urban buildings and more heterogeneous land cover patterns in 2000. A threshold of GVF (~0.21) was estimated for determining the change of albedo associated with vegetation fraction. Vegetation cover modified by urban expansion changed surface reflectance and influenced the surface energy balance. It is suggested that a large portion of energy absorbed in an urban area is likely to be converted to thermal energy that heating up is near the surface and emitted as longwave radiation.     

Fire danger assessment with remote sensing: a case study in Northern China

Every year several million hectares of forest and grassland in China are affected by wildfires. The majority of wildfires occur in the northern part of China, where grasslands and forests are ubiquitous. A critical step toward the protection of life, property, and natural resources from wildfires is the development of a fire danger rating system. This paper presents a new method to assess fire danger that capitalizes on the abundance of environmental data available via remote sensing and applies this new method to the northern part of China. Using an analytical hierarchy process, a fire danger index was developed based on five environmental factors that are known to affect fire frequency and severity, including land surface temperature, vegetation curing, equivalent water thickness, vegetation continuity degree, and fuel weight. Data for these five factors were derived from satellite imagery, instead of point data, allowing for predictions to be made over a large geographic area. Fire danger ratings were then mapped for the region based on the fire danger index. In addition, the accuracy of the fire danger index was evaluated by statistical analyses. The fire danger index was significantly correlated with air temperature and precipitation, suggesting that changes in these two environmental variables will affect the predictions of the index.     

喀斯特生态环境风险评价——以贵州省为例

区域生态环境风险评价具有尺度大、风险源与风险受体多、空间异质性强等特点,开展区域生态环境风险研究是识别生态环境风险水平、制定防范应对策略的重要理论支撑。文章以贵州省为例,参考相对风险模型为风险评价原则,基于自然灾害成因,综合考虑区域自然及经济状况,建立贵州省喀斯特生态环境风险评价框架与指标体系,运用层次分析法及系统聚类分析法,对各评价单元的危险性、暴露性、脆弱性、防灾减灾能力进行分析,并划分了区域风险程度等级。结果表明:贵州省喀斯特生态环境风险分布与生态环境本底和社会经济发展水平相关性明显,高风险区主要分布在生态环境脆弱的高原山地、高原峡谷地区以及综合发展水平较高的贵阳中心城区,低风险区主要分布在喀斯特分布面积少、生态本底好、自然灾害较少的黔东南及黔西北地区。      

Qualitative risk assessment schemes using selected parameters for hillslope developments: a case study of Penang Island

Development of hilly areas requiring deforestation and increased human activities has raised many environmental issues in the world. This paper presents the results of investigation to assess the parameters that contribute to the risk to environment by reviewing available reports from Penang Island and surrounding areas. Nine parameters were identified that mostly contribute to the environmental risk. These are casualties of people, soil properties, earth coverage, soil grading characteristics, land use suitability, factor of safety, blasting area, distance between proposed structure to slope and geometry of slope. From these parameters, the rated risk approaches were proposed based on the prediction of occurrences of environmental issues. The rated risks were categorised from very high (5) to very low (1) with high, medium and low in between. The assessments were reviewed and evaluated based on rated risk for the chosen parameters. A map was developed identifying areas of environmental risk. The map can be used to quantify risk to the environment based on the parameters due to the proposed development. The overall result shows that areas PD3 of Tanjung Bungah and PD3, PD8 and PD9 of Paya Terubong have high-rated risk. No development area is classified as very high risk and very low-risk areas. These rating approaches can be used to develop potential risk zoning of proposed development areas. From this zoning guideline or standard, the viability of any proposed development can be measured.     

岩溶地区旅游生态安全评价及趋势分析——以广西为例

岩溶地区拥有丰富的旅游资源,但是生态环境相对脆弱,根据岩溶地区旅游发展的特点,以"压力-状态-响应"（PSR）模型为基础,同时从生态安全的概念出发,涵盖生态风险、生态健康和生态足迹指标,建立了岩溶地区旅游生态安全评价指标体系。调整的主要指标包括:土地压力指标、旅游经济密度、年平均气温和年平均降雨量指标、旅游空间密度、游客密度指数、旅游收入指标等。采用综合指数法和熵权法,分别引入2012年和2007年两年的数据,对广西岩溶地区旅游生态安全的现状、发展趋势及变化趋势的内在原因进行了分析。实证结果表明:（1）从现状评价看,2007、2012年广西岩溶地区旅游生态安全水平总体较低,处于安全级别的城市主要位于广西中部区域,其他城市则处于不安全级别;（2）从影响指标看,经济状态和旅游生态状态对当地的旅游生态安全影响较大;（3）从变化趋势看,广西岩溶地区旅游生态安全状态逐渐好转,广西中部地区保持安全状态,紧邻广西中部地区的地市处于持续危险区域,但综合指数呈上升趋势;梧州和贵港两个位于广西东部的城市同样处于持续危险区域,但是旅游生态安全综合指数呈小幅下降趋势;（4）旅游生态安全状态和趋势与岩溶分布没有显著的相关关系。      

Geochemical investigation of groundwater in a Granitic Island: a case study from Kinmen Island,Taiwan

Kinmen Island is principally composed of low permeable granitoid and covered by a very thin sedimentary layer. Both surface and groundwater resources are limited and water demand is increasing with time. The groundwater in the granitoid has been surveyed as an alternative water source for daily use. Two to five highly fractured zones in the granitoid aquifer for each site were first determined by geochemical well logging. Accordingly, ten samples were collected from three sites. Using environmental isotopes and geochemical modeling, geochemical processes occurring due to water–rock interaction in the granitoid aquifer can be quantitatively interpreted. The stable isotopes of oxygen and hydrogen in groundwaters cluster along Taiwan’s local meteoric waterline, indicating evaporation does not have considerable effect on groundwaters. Given such a high evaporation rate for Kinmen Island, this result implies that infiltration rate of groundwater is high enough to reduce retention time through a well-developed fracture zone. NetpathXL is employed for inverse geochemical modeling. Results determine gypsum as being the major source of sulfate for deep groundwaters. The contribution from pyrite is minor. In addition, the weathering of albite to kaolinite is the dominant water–rock interaction characterizing geochemical compositions of deep groundwater in Kinmen Island.     

Determination of ecological significance based on geostatistical assessment: a case study from the Slovak Natura 2000 protected area

The Sitno Natura 2000 Site covers an area of 935,56 hectares. The Sitno region is significant due to the number of rare and endangered species of plants, and as a result is considered a location of great importance to the maintenance of floral gene pools. The study area suffers human impacts in the form of tourism. The main purpose of this study is to the measure landscape elements, determine the ecological significance of habitats within the Sitno area, and from this data, organize the study area into conservation zones. The results of this landscape quantification are numerical values that can be used to interpret the quality of ongoing ecological processes within individual landscape types. Interpretation of this quantified data can be used to determine the ecological significance of landscapes in other study areas. This research examines the habitats of Natura 2000 Sites by a set of landscape metrics for habitat area, size, density, and shape, such as Number of patches (NP), Patch density (PD), Mean patch size (MPS), Patch size standard deviation (PSSD) and Mean shape index (MSI). The classification of land cover patches is based on the Annex Code system.     

Qualitative hazard and risk assessment of landslides: a practical framework for a case study in China

Natural Hazards - Landslides are presented in various types; some of which are unique or completely different from those in other countries due to geological conditions in China. Baoji City in...     

Risk perception in small island developing states: a case study in the Commonwealth of Dominica

Natural Hazards - Small island developing states (SIDS) face high vulnerability to natural hazards; thus, understanding risk perception in SIDS is an essential step toward reducing vulnerability. A...     

Dynamic analysis of emergency inter-organizational communication network under public health emergency: a case study of COVID-19 in Hubei Province of China

Storm surge induced by hurricane is a major threat to the Gulf Coasts of the United States. A numerical modeling study was conducted to simulate the storm surge during Hurricane Michael, a category 5 hurricane that landed on the Florida Panhandle in 2018. A high-resolution model mesh was used in the ADCIRC hydrodynamic model to simulate storm surge and tides during the hurricane. Two parametric wind models, Holland 1980 model and Holland 2010 model, have been evaluated for their effects on the accuracy of storm surge modeling by comparing simulated and observed maximum water levels along the coast. The wind model parameters are determined by observed hurricane wind and pressure data. Results indicate that both Holland 1980 and Holland 2010 wind models produce reasonable accuracy in predicting maximum water level in Mexico Beach, with errors between 1 and 3.7%. Comparing to the observed peak water level of 4.74 m in Mexico Beach, Holland 1980 wind model with radius of 64-knot wind speed for parameter estimation results in the lowest error of 1%. For a given wind model, the wind profiles are also affected by the wind data used for parameter estimation. Away from hurricane eye wall, using radius of 64-knot wind speed for parameter estimation generally produces weaker wind than those using radius of 34-knot wind speed for parameter estimation. Comparing model simulated storm tides with 17 water marks observed along the coast, Holland 2010 wind model using radius of 34-knot wind speed for parameter estimation leads to the minimum mean absolute error. The results will provide a good reference for researchers to improve storm surge modeling. The validated model can be used to support coastal hazard mitigation planning.

     

中国东南沿海与西南日本白垩纪-古近纪火山-侵入岩带的地球动力学特征

本文讨论了中国东南沿海和西南日本两条白垩纪-古近纪火山-侵入岩带的地球动力学特征。两条火山-侵入岩带的下火山岩系岩石经受了左旋走滑的韧性剪切变形而形成片理或片麻理构造。中国东南沿海火山-侵入活动的起始时间、动力变形和结束时间都早于日本约30Ma。西南日本高镁安山岩和埃达克岩(120~105Ma)是在大面积白垩纪岩浆作用的起始阶段由大洋俯冲板片在高温条件下部分熔融形成的。火山-侵入活动的结束标志中国东南沿海岩浆岩带是板内环境的晶洞A型花岗岩和以流纹岩为主的双峰式火山岩;在西南日本岩浆岩带是年轻地壳挤压重熔的S型过铝质石榴石/白云母细粒花岗岩和流纹岩,不存在类似华南的壳源S型花岗岩,中国东南沿海没有代表洋壳俯冲的弧岩浆岩。两条火山-侵入岩带的源区都以幔源为主并有前寒武纪再旋回地壳物质加入,它们的Sr-Nd同位素组成表明:随时间推移,中国东南沿海火山-侵入岩中幔源组分增加,而西南日本则相反。华南中生代大规模岩浆活动的开始(170±5Ma)是在古太平洋板块斜向俯冲背景下,大陆岩石圈减薄,陆内深断裂再活化的结果。东亚大陆边缘在晚中生代(120Ma)进入古太平洋板块正向俯冲构造体系,但不同地段的表现不同。     

Optimization design and assessment of the effect of seepage control at reservoir sites under karst conditions: a case study in Anhui Province,China

Seepage analysis and assessment of the effect of seepage control at reservoir sites are essential parts of dam design and operations, and of considerable significance for the safe and economic design of the masses and hydraulic structures associated with reservoir sites. In this study, a systematic process is provided for the optimal design and assessment of seepage control of reservoir dams under karst development conditions. A reservoir dam planned for construction in the middle-upper reaches of the Huayang River in China is selected as a case example for illustration. A three-dimensional equivalent continuum seepage finite-element numerical model is applied to investigate the effectiveness of the proposed and optimized seepage-control schemes, and it is calibrated by an inversion analysis of the initial seepage field based on the flexible tolerance method and field penetration test data. By analyzing the sensitivity of seepage discharge to the length and depth of the grouting curtain, a safe and economic seepage-control optimization scheme is suggested. Additionally, the sensitivity of seepage discharge to the hydraulic conductivity of the limestone layer is analyzed, and the results show that the hydraulic conductivity of the limestone layer has a significant impact on the seepage discharge of the reservoir site. The methodology and results derived from this study can provide technical support and reference for the optimal design and assessment of seepage control for reservoir dam engineering under karst conditions.

     

东南沿海及南海新生代火山作用与南海的形成演化

中国东南沿海地区和南海海域新生代火山岩系列、类型和SrNd同位素特征十分相似,具有板内玄武岩的特征。根据南海扩张时代,将新生代的火山岩划分为扩张期前、扩张期和扩张期后3大阶段,并利用原生岩浆推导了软流圈岩石圈的一些深部作用特征。扩张期前（接近扩张期）和扩张期软流圈顶部埋深较浅。从扩张期前（接近扩张期）到扩张期软流圈顶部埋深变浅,隙间熔浆增加,原生岩浆的演化具有前进式裂谷火山作用的演化序列,岩石圈扩张速率变大。从扩张期到扩张期后（直至第四纪）,软流圈顶部埋深逐渐变深,隙间熔浆减少,原生岩浆的演化表现出后退式裂谷火山作用的序列,岩石圈扩张速率逐渐变慢。新生代火山作用显示出的深部作用特征与南海的扩张和闭合一致,这为我们提供了南海形成和演化的深部作用证据。