Rockfall Hazard and Risk Assessment Along a Transportation Corridor in the Nera Valley,Central Italy

Rockfalls are a common type of fast-moving slope failures, and in many countries they represent the primary cause of landslide fatalities. We present a methodology to ascertain rockfall hazard and to determine the associated risk along transportation networks. The proposed methodology is based on the combined analysis of the recurrence of rockfall events, determined from historical information, the frequency-volume statistics of rockfalls, obtained from inventories of recent rockfall triggering events, and the results of a physically based, spatially distributed rockfall simulation model used to determine rockfall hazard. The available information on rockfall hazard is combined in a Geographic Information System with a map of the transportation network to identify the road sections potentially subject to rockfalls. Information on the location and type of rockfall defensive measures, including revetment nets, elastic fences, concrete walls, and artificial tunnels, is used to estimate the efficacy of the defensive structures and to determine the level of the residual rockfall risk along the roads. To illustrate the methodology, we discuss an application in a 48-km² area in the Nera River valley, in the Umbria Region of central Italy, where rockfalls are abundant, and where considerable investments were recently made to mitigate rockfall risk. Note: This version was published online in June 2005 with the cover date of August 2004.     

计算机网络安全的防范措施

随着传播媒体和信息技术高速发展，Internet广泛应用，共享信息与网上业务在不断增加。伴随而来的网络攻击和犯罪日益猖橛。本文概要地介绍了网络信息安全面临的主要威胁，阐述了计算机网络安全的基本防范措施。     

北京市城乡交错带土地利用调控对策

城乡交错带是城市扩展和农村发展的前沿,也是统筹城乡关系的重点地区.选择北京市城乡交错带为研究区域,以调查统计、变更调查和实地调查资料为基础,采用统计分析和综合的方法,认为北京市城乡交错带20世纪80年代以来土地利用变化具有以城市发展为主、国家建设占用和点轴面的外延扩展方式的特点,从而导致交错带的生态屏障功能日益受到蚕食,合理的用地功能布局和用地效益受到影响.建议采取加强城乡一体化编制土地利用总体规划、调整结构和优化布局等调控措施.     

硫化氢的危害与防治

对硫化氢在油气田中的存在状况和危害性的研究结果表明,其主要危害是引起人员中毒以及氢脆作用造成的油田设备腐蚀。详细介绍了防治硫化氢的方法和措施,包括沉淀法、物理吸收法、钾碱法和氨水法、氧化法、金属氧化物吸收法、高压静电法等。对各种方法的防治机理及其应用状况进行了论述。     

福建省农业自然资源持续利用探讨

本文分析了福建省农业自然资源利用中存在的突出问题及其形成原因,并根据持续发展新模式提出了持续利用的对策。     

论区域污染治理的经济机制

本文分析了我国区域环境保护面临的困难,指出了造成这些困难的原因主要是地方政府卷入企业过深、区域经济结构中低水平企业比重过大、生产和消费活动中环境滥用普遍等,并提出了在承认环境价值的条件下,建立和完善区域间和区域内环境保护的经济机制的建议。     

试论洞庭湖区的洪涝灾害及其减灾对策

洞庭湖区频繁而严重的洪涝灾害是其孕灾环境的易灾性及承灾体较低的承灾能力共同决定的．减轻洞庭湖区的洪涝灾害应实行“治江、控制四水与洞庭湖本身治理”三位一体的综合整治战略．     

太湖流域洪涝的激发机制和减灾策略探讨

太湖流域洪涝灾害的形成包括自然和人为两方面的机制。自然机制有：①年降雨量较大，且降雨时空分布不均，暴雨强度大；②地势周高中低，平原海拔低，河流比降小。人为机制有：①围垦缩小了流域蓄水面积；②地下水开采和高层建筑造成地面沉降；③土地非农业化使地表可渗透性面积减少。并提出洪涝威胁的发展趋势及减灾对策。     

The use of invertebrates to detect small-scale habitat heterogeneity and its application to restoration practices

Recent conceptual and technological solutions to biodiversityassessment allow large numbers of invertebrate specimens to beprocessed rapidly and provide researchers and practitioners with a unique tool for characterizing habitats. One applicationof these advances is the ability to detect and monitor small-scale habitat heterogeneity and so provide a measure of ecosystem restoration. This case study presents a test of theefficacy of using invertebrates to assess and monitor ecologicalrestoration following bush regeneration. Eight contiguous habitatpatches within a suburb of northern Sydney, Australia, were selected to represent areas that had undergone different bushregeneration techniques. A nearby and relatively undisturbed area of bushland was also sampled. A total of 57 806 ground-active invertebrate specimens from 35 different orders were collected in pitfall traps. 1 246 ant (Formicidae) specimens were further sorted into 46 ant morphospecies from20 genera. Analyses of the three taxonomic data sets, includingtwo different data transformations, demonstrated that: (i) invertebrate communities successfully characterized different sites, providing a high degree of differentiation among sites;(ii) ordinations of the sites allowed visual assessment of theimpact of each management technique on the habitat relativeto undisturbed habitats; and (iii) characterization of sitescould be achieved using abundance classes or binary countsof ant morphospecies, representing potential cost and timesavings. The project duration was a total of three personweeks and cost less than US$3,000 (1999 prices) to complete.Measurement of invertebrate assemblages will provide a toolfor both rapid assessment of management decisions and ameans by which to implement adaptive management and restoration.     

Landscape ecological planning through a multi-scale characterization of pattern: studies in the Western Ghats,South India

This article analyzes landscape pattern in the WesternGhats mountain ranges in south-western India at two scales,comparing small-scale, detailed studies of landscapepattern, with broader, regional-scale assessments of theWestern Ghats. Due in large part to their inaccessibility,relatively little is known about the landscapes of thisbiodiverse region, which also supports some of the highestpopulation densities in the world. A broad-scale NDVI-basedIRS 1B satellite image classification is used to analyzenorth-south and east-west trends across the entire WesternGhats and western coast of India, an area over 170 000 km². Northern and eastern landscapes are morefragmented compared to the southern and western slopes.Western slopes also have greater landscape diversity withland cover types more interspersed compared to the easternslopes. These differences can be related to north-south andeast-west variations in rainfall and plant distribution. Data from thirteen landscapes 10–50 km² in area, arefurther utilized to analyze trends in landscape pattern, anddescribe the geographical distribution of major natural andmanaged ecotope types. At this scale, very high levels ofintra-ecotope type variability in landscape pattern areencountered for all land cover types. Results at these twoscales are integrated to suggest a hierarchical stratifiedapproach for monitoring land cover and biodiversity in the region.