The current status of mapping karst areas and availability of public sinkhole-risk resources in karst terrains of the United States

Subsidence from sinkhole collapse is a common occurrence in areas underlain by water-soluble rocks such as carbonate and evaporite rocks, typical of karst terrain. Almost all 50 States within the United States (excluding Delaware and Rhode Island) have karst areas, with sinkhole damage highest in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania. A conservative estimate of losses to all types of ground subsidence was $125 million per year in 1997. This estimate may now be low, as review of cost reports from the last 15 years indicates that the cost of karst collapses in the United States averages more than $300 million per year. Knowing when a catastrophic event will occur is not possible; however, understanding where such occurrences are likely is possible. The US Geological Survey has developed and maintains national-scale maps of karst areas and areas prone to sinkhole formation. Several States provide additional resources for their citizens; Alabama, Colorado, Florida, Indiana, Iowa, Kentucky, Minnesota, Missouri, Ohio, and Pennsylvania maintain databases of sinkholes or karst features, with Florida, Kentucky, Missouri, and Ohio providing sinkhole reporting mechanisms for the public.     

岩溶区生态恢复与重建的初步效果及意义

介绍了中国-斯洛文尼亚科技合作项目<利用有益动物繁殖系统进行岩溶地区的休养再生示范>实施的背景与岩溶区生态恢复重建的思路.通过试验,已找到桂北岩溶区适生的优良牧草和灌木品种.研究发现,这些品种对岩溶区的物种多样性、生态级别、土壤养分、土壤特性、土壤水涵养性等均有明显的改善作用,为中国南方岩溶区生态恢复与重建提供了科学依据.     

岩溶区生态恢复与重建的初步效果及意义

介绍了中国-斯洛文尼亚科技合作项目《利用有益动物繁殖系统进行岩溶地区的休养再生示范》实施的背景与岩溶区生态恢复重建的思路。通过试验,已找到桂北岩溶区适生的优良牧草和灌木品种。研究发现,这些品种对岩溶区的物种多样性、生态级别、土壤养分、土壤特性、土壤水涵养性等均有明显的改善作用,为中国南方岩溶区生态恢复与重建提供了科学依据。     

贵州高原岩溶台地红色风化壳的物源辨析

贵州高原岩溶台地上广泛分布着相对均一(通常3～5ｍ)的红色风化壳,是中国南方红色风化壳的重要组成部分。但对岩溶台地红色风化壳的成因及其物源长期存在争议。作者最近在黔西、黔中、黔北和黔东等地选取了数十个岩溶台地垄岗之上红色风化壳剖面,运用矿物学、地球化学等方法,首次系统研究了它们的物质来源及成因,认为它们与下伏基岩有明显的继承性,是碳酸盐岩中酸不溶物原地风化残积的产物。碳酸盐岩红色风化壳往往没有明显的半风化过渡带,剖面主体由成分均一的全风化土层构成,仅在土层之下有数厘米到十多厘米厚的碳酸盐岩岩粉层出现,岩-土界面清晰、突变。     

DEFLOGIC: a method for assessment of groundwater potential in karst terrains: Gurpi Anticline,southwest Iran

A new hydro-tectonic model, includes eight layers that affect karst hydrogeology was proposed for mapping of groundwater potential in karst areas of Gurpi Anticline, southwest Iran. To produce the groundwater potential map, remote sensing (RS) and GIS techniques were combined with fuzzy logic modeling. Criterion maps include the distances from discharge sites (D), the elevation difference from discharge sites (E), the distance from fractures (F), the fracture length density (L), the slope (O), the lithology (G), the distance from fractures intersections (I), and the fractures intersection density (C) were produced using GIS and RS techniques (DEFLOGIC layers). The approach of fuzzy sets was used to commensurate criterion maps, then fuzzy algebraic sum and gamma operators were applied to aggregate them. The weights of parameters of DEFLOGIC proposed in the range of 1 to 5, which standardized between 0 to 1, based on their importance in karst hydrogeology, professional judgments, and available exploration data. The final groundwater potential maps were verified by geoelectric and well-drilling data. The potential map prepared using fuzzy gamma operator with γ?=?0.92, which it is a flexible distinctive parameters of sum and product of fuzzy operator, depicts the best coincidence with exploration data. The final DEFLOGIC map shows the high groundwater potential in karst formations between Hati and Pebde valleys. The results support the efficiency of DEFLOGIC model to evaluating of groundwater potential in karst terrains, especially in Zagros ranges.     

碳酸盐岩洞穴充填物及其充填程度的测井判别方法

近年来在新疆塔里木盆地发现了超亿吨级的碳酸盐岩大型油气田,洞穴型碳酸盐岩储层是其非常重要的储层类型之一,而此类储层的有效性取决于洞穴中充填物及充填程度,由于此储层中的洞穴横向变化可延伸至几米甚至几十米,远远超过了仪器的探测深度,因此对它的充填程度及其充填物的有效识别仍是目前待攻关的难题。通过分析不同充填程度、不同充填物的洞穴在常规测井曲线、电成像和阵列声波图像上的响应特征以及交会图分析法来识别洞穴充填物的性质,并结合钻井、录井、试井及地震等方面的识别标志,将洞穴型储层划分为完全充填洞穴储层、半充填以及未充填洞穴储层。      

喀斯特人地关系地域系统的结构与功能刍议─—以贵州民族地区为例

人地关系的协调必须按地域类型进行。由于特殊自然条件的影响,喀斯特环境具有与非喀斯特环境大为不同的特殊地域结构和功能,其形成的主要原因是以碳酸盐岩为主的景观各组成要素间的相互作用和中小尺度地域分异规律的影响,其结果产生不同类型的地域单元并在空间形成有序结构,从而导致具有特色的喀斯特人地关系地域类型的形成。     

适用于地质灾害调查的微型无人机航线控制系统设计与实现

传统的地质灾害野外调查手段已经不能满足日益增长的快速获取信息的需求以及国家精细化地质调查的要求,因此近年来掌上机、无人机、InSAR、高精度遥感等技术在地质灾害调查研究领域得到了不同程度的应用。文章紧密结合地质灾害调查数据采集业务需求和工作流程要求,以微型无人机为采集端,采用无人机技术、地理信息技术和图像融合技术,基于Android系统设计了适用于地质灾害野外调查微型无人机航线控制系统,开发了航线规划、智能续飞、图像快拼、离线地图以及针对不同形态灾害体的不同拍摄模式等功能,实现采集流程全自动化,为地质灾害调查人员提供了快速、便捷的无人机遥感影像数据采集手段,为地质调查工作提供了直观、精准的数据支撑。     

Landslide hazard and risk assessment mapping of mountainous terrains - a case study from Kumaun Himalaya, India

Landslides are studied systematically in order to evaluate the nature of hazard and the damages to the human life, land, roads, buildings and other properties. This can be expressed in terms of risk, which is a function of hazard probability and damage potential. A risk map will indicate the priorities for landslide hazard management. A new approach to risk assessment mapping using a risk assessment matrix (RAM) is presented.     

面向领导决策的地质灾害预警系统设计与实现

利用GIS技术对地质灾害信息进行快捷发布、预警与决策,是地质灾害管理与防治的有效途径之一。基于地质灾害预警与领导决策的需求,对结合ArcIMS地图服务与Ajax技术的地质灾害预警系统的目标、结构、功能、数据模型与数据库进行了分析与设计,探讨了系统开发所涉及的关键技术。最终完成了基于Ajax模式的广东省地质灾害预警系统的开发,实现了地质灾害相关信息的分析,灾害等级划分与预警,以及灾害信息的发布。     

Void-filling deposits in karst terrains of isolated oceanic islands: a case study from Tertiary carbonates of the Cayman Islands

Caves, fossil mouldic cavities, sinkholes and solution-widened joints are common in the Cayman and Pedro Castle members of the Bluff Formation (Oligocene-Miocene) on Grand Cayman and Cayman Brac because they have been subjected to repeated periods of karst development over the last 30 million years. Many voids contain a diverse array of sediments and/or precipitates derived from marine or terrestrial environs, mineral aerosols, and groundwater. Exogenic sediment was transported to the cavities by oceanic storm waves, transgressive seas, runoff following tropical rain storms and/or in groundwater. At least three periods of deposition were responsible for the occlusion of voids in the Cayman and Pedro Castle members. Voids in the Cayman Member were initially filled or partly filled during the Late Oligocene and Early Miocene. This was terminated with the deposition of the Pedro Castle Member in the Middle Miocene. Subsequent exposure led to further karst development and void-filling sedimentation in both the Cayman and Pedro Castle members. Speleothems are notably absent. The void-filling deposits formed during these two periods, which were predominantly marine in origin, were pervasively dolomitized along with the host rock 2–5 million years ago. The third period of void-filling deposition, after dolomitization of the Bluff Formation, produced limestone, various types of breccia, terra rossa, speleothemic calcite and terrestrial oncoids. Most of these deposits formed since the Sangamon highstand 125 000 years ago. Voids in the present day karst are commonly filled or partly filled with unconsolidated sediments. Study of the Bluff Formation of Grand Cayman and Cayman Brac shows that karst terrains on isolated oceanic islands are characterized by complex successions of void-filling deposits that include speleothems and a variety of sediment types. The heterogenetic nature of these void-filling deposits is related to changes in sea level and climatic conditions through time.     

A method for assessing and managing landslide residual hazard in urban areas

On February 14, 2010, a large landslide affected the urban centre of San Fratello town (Sicily Island, Southern Italy), causing severe damage to buildings, roadways, and infrastructure, as well as about 2000 evacuees. This large complex landslide, covering more than 1 km² in extension, represents one of the major phenomena that ever occurred in Sicily. In order to manage the landslide risk, the civil protection system was activated as part of the initial response to the emergency (the “emergency phase”). This involved the Civil Protection Departments both at national (DPC) and regional (DRPC) levels, as well as scientific institutions (namely “Competence centres”, CdCs), local administration personnel, and technicians. On March 8, 2010, during the post-event recovery phase, a ground-based synthetic aperture radar (GB-InSAR) system was installed in order to monitor the ground surface deformation, assess the landslide residual risk, and analyse its displacement trend. Accurate field surveys and building inspections were also performed for a validation of the GB-InSAR data, in order to map the ground deformation, plan building evacuation-demolishment, as well as check the efficiency of the landslide mitigation works. This paper describes the outcomes of the 57 month monitoring campaign (March 2010–December 2014), reporting the use of GB-InSAR data for near real-time monitoring, mapping, and post-emergency/recovery management activities. The final aim was to provide the civil protection personnel with a reliable, rapid, and easy communication system of the monitoring results, designed to an enhance understanding of the landslide phenomena, and to support the decision-making process.     

防治公路岩溶塌陷的土工合成材料设计理论研究

高速公路路基岩溶塌陷通常可以采用水平加筋体防治,系统地研究其受力特性及设计理论具有重要的工程意义和实际价值。首先,针对公路路基荷载及岩溶塌陷的特点,分析了塌陷坑上方水平加筋体的受力和传力特性,采用太沙基土拱理论,计算溶洞上方荷载。深入探讨了水平加筋体设计方法,认为锚固段端部加筋体应变及锚固段传力长度是设计中的关键值,且其与锚固段端部加筋体拔出量密切相关。然后,引入水平加筋体与土体界面的线弹性-全塑性模型,由基本方程导出锚固段水平加筋体弹塑性解答,并结合边界条件建立了锚固段端点拔出量及传力长度的解算流程。在此基础上,引入某实际工程计算参数进行分析,将该方法结果与基于全塑性模型的分析结果进行对比,探讨了不同临空段宽度、加筋体刚度、上覆土体高度、界面摩擦角等因素对临空段端部拔出量计算误差的影响,并分析了上覆土体高度与锚固段传力长度之间的关系。由分析可知,基于线弹性-全塑性模型计算的拔出量和传力长度均较全塑性模型计算结果大,某些情况下,传力长度的计算误差高于40%,若采用全塑性模型计算有可能引起较大的误差,导致设计偏于不安全     

岩溶浸没内涝灾害灾情评估方法探讨

岩溶浸没内涝灾害是岩溶区特有的,并且是一种与人类社会经济密切相关的灾害类型.减轻并控制其所造成的危害和影响,对岩溶区的经济持续发展具有重要的意义.岩溶浸没内涝灾害风险评价是指对灾害全过程的综合分析与研究.评价的目的①对灾害造成的经济损失作出评估;②不断提高人类抗御灾害的认识能力和技术能力.岩溶浸没内涝灾害风险评价方法学是科学方法的跨学科运用,它以岩溶多重介质环境中地表水系为主线,岩溶地下河系为支线.二者相互交叉组成的岩溶地表地下流域网络单元为研究对象,应用地质、地理、数学、物理、化学等多学科的理论与方法,研究由自然和人为因素引起的造成人员伤亡和物质财富损毁的灾害过程,本文将重点对此进行讨论.     

Hydrogeological characterization and environmental effects of the deteriorating urban karst groundwater in a karst trough valley: Nanshan,SW China

The unique hydrogeology of karst makes the associated groundwater respond quickly to rainfall events and vulnerable to anthropogenic pollutions. In this study, high-frequency monitoring of spring discharge, temperature, electrical conductivity (EC) and pH, along with monthly hydrochemical and microbial analyses, was undertaken at the outlet of Laolondong karst underground river in Nanshan, southwestern China. The aim was to explore the environmental effects of the catchment’s urban area on the karst groundwater resources. The monitoring data of a tracer test and the response of discharge to rainfall events demonstrate that conduits and narrow fissures coexist in the Laolongdong karst aquifer. The EC, Na⁺, Cl^? and SO₄^2? values (840 μS/cm, 33.7, 38.6 and 137.2 μg/L, respectively), along with high concentrations of fecal coliform bacteria, at the outlet indicate considerable urban pollution in this area. The contaminants sulfate and nitrate showed different relationships with discharge and EC in different stages of a rainfall event. This behavior provided information about aquifer structure and the influence of transport properties. Meanwhile, the hydrological processes of groundwater flow could be modified by urbanization and result in increasing magnitude of urban floods in the underground river. In addition, sulfuric and nitric acids introduced by urbanization not only impact the karst groundwater quality, but also result in a significant perturbation to the carbon cycling system in the karst area.     

Effects of restricted recharge in an urban karst system

Urban karst systems are typically considered more vulnerable to contamination and excess storm discharge because of potential source areas, increased sediment loading, and focusing of water from impervious surfaces. However, urban hydrology can lead to unexpected patterns, such as pirating of recharge into man-made storm systems. Valley Creek Basin in southeastern Pennsylvania, presents such an urban karst system. Four springs were monitored for suspended sediment, water chemistry, and storm response for an 18-month period. The baseflow suspended sediment concentrations were low, less than 4.0 mg/l. Furthermore, trace metal analysis of baseflow water samples and spring mouth sediment showed only low concentrations. The response to storms within the system was rapid, on the order of 1–3 h. The maximum water stage increases at the urban springs were typically less than 15 cm, with springs from more commercialized areas showing <2 cm increase. A nearby retention basin, in contrast, had water level rises of 100 cm, suggesting that pirating of recharge into stormwater systems occurs. Thus, the concept of an urban karst system as a contaminant conduit is not the only one that applies. In Valley Creek Basin, reduced infiltration due to paving led to smaller storm response and less contaminant input, and the smaller capture area due to diversion of stormwater led to short flow paths and rapid storm response. Although contaminant levels have not increased due to urbanization, the springs may be at risk for future contamination. Short flow paths may reduce flushing, which means that the system will not cleanse itself if contamination occurs.     

Development of a parameterization for simulating the urban temperature hazard using satellite observations in climate model

Urban surface temperature is hazardously higher than surrounding regions (so-called urban heat island effect UHI). Accurately simulating urbanization-induced temperature hazard is critical for realistically representing urban regions in the land surface-atmosphere climate system. However, inclusion of urban landscapes in regional or global climate models has been overlooked due to the coarse spatial resolution of these models as well as the lack of observations for urban physical properties. Recently, National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS) observations illustrate important urban physical properties, including skin temperature, surface albedo, surface emissivity, and leaf area index, It is possible to identify the unique urban features globally and thus simulate global urban processes. An urban scheme is designed to represent the urban-modified physical parameters (albedo, emissivity, land cover, roughness length, thermal and hydraulic properties) and to include new, unique physical processes that exist in urban regions. The urban scheme is coupled with National Center for Atmospheric Research (NCAR) Community Land Model Version 2 (CLM2) and single column coupled NCAR Community Atmosphere Model CAM2/CLM2 to assess the mechanisms responsible for UHI. There are two-steps in our model development. First, satellite observations of albedo, emissivity, LAI, and in situ observed thermal properties are updated in CLM2 to represent the first-order urban effects. Second, new terms representing the urban anthropogenic heat flux, storage heat flux, and roughness length are calculated in the model. Model simulations suggest that human activity-induced surface temperature hazard results in overlying atmosphere instability and convective rainfall, which may enhance the possibility of urban flood hazard.