浙江省泥石流形成及成灾特点

浙江地处我国东南沿海,近几年频繁遭受泥石流等山地灾害的危害。由于所处地理地质和气候环境,发育的泥石流有其独特的地域特征。从泥石流的发育特征、形成过程等探讨了浙江泥石流形成的机理,分析了其成灾特点。结果表明,浙江省泥石流为滑坡、崩塌转化型泥石流,泥石流的形成机理及过程主要为:强降雨下滑坡、崩塌发生,持续强降雨使得滑坡、崩塌松散物流化从而形成泥石流。滑坡、崩塌转化型泥石流在流域特征上表现为形成区坡度大,易发滑坡、崩塌,水力条件充分等。泥石流灾害具有低频性、群发性、并发性、突发性、夜发性、危害大等特点。     

5·12汶川地震龙门山风景区地震次生山地灾害特征与处理

5·12汶川地震激发了龙门山风景区崩塌、滑坡、泥石流、堰塞湖等链状次生山地灾害.通过应急调查发现,该区已有堰塞湖5处,危害性崩塌、滑坡6处,已成灾泥石流沟1条,潜在泥石流沟11条,根据各处灾害的主要特征,确定堰塞湖的危险程度,提出山地灾害处理建议.     

群发性泥石流的危害效应及防范探讨

由于目前对群发性泥石流形成机理及成灾模式的研究甚少,加之在防范经验上的欠缺,难以找到有效的办法来降低这类泥石流造成的危害.为此,针对2010年群发性泥石流灾害频发事件,以近年来四川省典型群发性泥石流灾害为例,探讨这类泥石流灾害的空间分布特征及其灾害效应,并对群发性泥石流成灾的"叠加-放大效应"及成灾的"链式效应"进行分析,对认识群发性泥石流的成灾规律有一定理论意义.最后,就群发性泥石流灾害的防范及对策进行了探讨,可为防灾减灾提供参考.     

5·12汶川地震龙门山风景区地震次生山地灾害特征与处理

5·12汶川地震激发了龙门山风景区崩塌、滑坡、泥石流、堰塞湖等链状次生山地灾害。通过应急调查发现,该区已有堰塞湖5处,危害性崩塌、滑坡6处,已成灾泥石流沟1条,潜在泥石流沟11条,根据各处灾害的主要特征,确定堰塞湖的危险程度,提出山地灾害处理建议。     

诱发滑坡的多尺度降雨特征

在全球气候变暖背景下,极端性降水导致滑坡泥石流等自然灾害频发,关于降水与地质灾害之间的关系引起公众广泛的关注。本研究在对降水过程进行定量化划分的基础上研究滑坡发生与降水之间的关系,基于全国气象台站的地面降水观测资料,对2658例滑坡事件中的前期降水量、本场激发降水量、极端性降水量等不同时间尺度的降水特征进行了系统性的统计分析。结果表明:绝大部分的滑坡事件都属于前期有效降水主导型;前期降雨在导致滑坡的各个因素中占主导性地位;滑坡灾害发生前10 d特别是前5 d的降雨是导致滑坡发生的关键因素,而且降水产生时间与滑坡事件发生时间相隔越长,其在诱发滑坡事件发生的过程中的作用也越小;本场激发降雨是诱发滑坡事件发生重要的影响因素,持续时间大多集中在6 h之内,且以强度大、时间集中为特点的短时降水为主;极端性降水也是导致滑坡事件的关键诱发因素,大部分滑坡事件中的前15 d有效降水量和当日本场降水量在历史同期降水序列中均超过第90百分位数,具有明显的极端性特征。本研究从全国的视角来系统性地分析研究滑坡与降雨之间的关系,将为全国范围内的滑坡地质灾害预警提供参考。     

广乐高速公路K70+500处泥石流地质灾害成因分析

广乐高速京港澳高速公路粤境段的复线,也是广东省新十项工程和高速公路"六纵"的重要组成部分,对地方经济发展具有重大意义。但山区高速公路段常受到滑坡、崩塌及泥石流等地质灾害危害,严重影响交通正常运营及公路行驶人员的生命财产安全。其中泥石流地质灾害具有危害性大,成因复杂等特征,通过泥石流地质灾害成因研究、分析,对泥石流防治具指导性作用。广乐高速公路K70+500处泥石流地质灾害为其中一处,属典型沟谷性泥石流,其成因与地貌、地质条件及气象等有密切关系。     

安徽南陵地质灾害类型及发育特征研究

南陵县位于安徽省中南部,地处沿江丘陵平原。该区地质构造复杂,地质环境脆弱,地质灾害时有发生。文章在收集已有资料基础上,叙述了南陵县地质灾害类型及发育特征。研究表明,崩塌是南陵县地质灾害主要类型,其次存在少量的地面塌陷、滑坡、泥石流。南陵县地质灾害空间分布与地质构造发育紧密相关,同时在时间上表现一定的相关性。地质灾害明显受地质构造控制,地质灾害类型的多种表现形式主要受人类活动、降水量与降水形式控制。     

“4·20”芦山地震震中龙门乡地质灾害特征

"4·20"芦山地震为龙门山断裂带南端上的浅源构造地震,震中位于四川省芦山县龙门乡马边沟,最大烈度达IX度,龙门乡99%以上房屋受损。乡境内因地震形成35处地质灾害,主要类型为滑坡、崩塌,分别占40.0%、60.0%,乡境内5个村有分布。崩塌失稳模式为震动-剥落、震动-拉裂-滑移、震动-拉裂-错落;滑坡失稳模式为震动-拉裂-蠕滑。地震地质灾害除受控于地震触发作用,陡峻的地形、地形与高程放大效应特征突出外,强风化卸荷作用也是地质灾害产生的物质基础。乡境内以崩塌危害较为严重。开展震中地震地质灾害特征研究,预测灾害发展趋势,对灾区安置点规划、灾后3 a恢复重建都将具有重要的指导意义。     

"5·12"汶川地震后北川苏保河流域泥石流危害及特征

汶川8级地震直接引发了大量的崩塌、滑坡等次生山地灾害,为泥石流提供了丰富的物质来源,灾后遇高强度降水,已引发大规模的次生泥石流灾害,严重威胁灾民安置点和灾后重建场址.以北川苏保河流域为例,分析了泥石流形成的地形地貌条件、松散固体物质条件和降水条件,总结了苏保河流域泥石流的危害和特征,在此基础上,通过形态调查法和雨洪法对泥石流流量的计算进行了对比分析.结果表明:地震后苏保河流域演变为泥石流多发区域,泥石流将会危害人民生命财产安全、灾后抢险救灾公路和人类生存环境;苏保河流域泥石流具有呈群发性,危害范围大、密度高,搬运能力强、激发泥石流的雨量相对偏小、多灾种复合性的特征;地震后,由于强震引发松散固体物质的剧增、地表植被破坏引起径汇流条件的变化、沟道性质的变化及沟道内形成的多级堵塞,使泥石流的规模增大.     

纳雍县沙包镇地质灾害分布特征及孕灾因素分析

本文借助ArcGIS软件,基于人机交互解译数据并结合已有成果,对贵州省纳雍县沙包镇地区内的崩塌、滑坡、岩溶塌陷和泥石流等地质灾害的分布特征、发育规律及其孕灾因素进行分析研究。研究结果表明:研究区内发育的地质灾害共计35处,其中发育滑坡20处,崩塌11处,泥石流1处,地裂缝2处,岩溶塌陷1处,以滑坡和崩塌为主。主要分布在纳雍县义中大河、扯瓜河及支流两岸陡斜坡地带在人类工程活动强烈的公路附近,受地形地貌、地层岩性、断裂带性质和人类工程活动的影响,在空间上具有不均匀性。在地形地貌、地层岩性、断裂带性质以及人类工程活动等因素的影响下,地质灾害点集中发育在峡谷地貌、河流切割强烈的地区,以软质岩类和硬质岩夹软质岩类分布的地区为主。     

Elevation, Age, Soil Development, and Chemical Weathering at Storbreen, Jotunheimen, Norway

Chemical weathering and associated soil development trends on glacial forelands are commonly assumed to exhibit increases with time elapsed since glaciation. However, this gross trend is complicated by several other factors including elevation, aspect, and microtopography. This paper demonstrates that on the glacial foreland at Storbreen, Jotunheimen, Norway, chemical weathering and associated soil development trends show significant elevational influences. We sampled soils at shallow depths (0–1, 1–5, and 15–20 cm) at two sites on a moraine dated to 1750 at its elevational extremes of 1155 m (site L) and 1385 m (site H). The two moraine sites also differed developmentally from an adjacent 9000-year-old surface (site T) at an intermediate elevation, 1205 m. Analyses were conducted on the fine-earth fractions. Extractable elemental composition exhibited detectable differences between the same-age soils at different elevations with the lower site L tending to have measured parameters intermediate between the high site H and the older site T. Weathering, as indicated by mineralogy, was more pronounced at the 9000-year-old site T and least evident at the high elevation site H. In addition, elevation under the conditions of the field research may inhibit pedogenesis as indicated by the chemical data. Site H, for example, showed little variation with depth and had in general, less organic matter accumulation, smaller C:N ratio, greater pH, and lesser amounts of the measured extractable elements than the soil at site L. Site T generally had smaller pH and larger levels of the measured elements than the other sites. It was concluded that elevation has a significant control on weathering and pedogenesis that may mask the effects of age in this cold and wet environment.     

Women,Politics, Elections,and Citizenship

Abstract

Significantly more women than men are registered voters in the United States, and a higher proportion of women voters actually cast ballots on election day. Yet the 106th Congress (1999-2001) includes only 56 women members, 12% of the total membership of the House and Senate. Likewise, women hold only 22% of the total seats in state legislatures. The purpose of this article is to examine this paradox. It first examines the history of the women's movement in the United States. It then turns to an evaluation of women's progress in gaining elected office. Finally it considers three primary obstacles to women gaining equitable representation: solidarity among women, political culture, and the single-member district system now employed in the United States.     

FANTASY,GEOGRAPHY, WAGNER,AND OPERA*

ABSTRACT. Wilhelm Richard Wagner fused fantasy based on epic and lore with seamless scores, using landscapes and urban images to forge spatial order on stage. As a footloose composer-conductor, Wagner was considered a globetrotter for his time, and from trans-European tours he drew inspiration for numerous stagings. Nine of his operas have rustic pastoral settings, with actors silhouetted against geological formations, forests, vistas of undulating terrain for pilgrimages, or raging seas, all visually believable scenery. Rienzi and Die Meistersinger von Nürnberg are urban in setting, whereas Die Feen and Das Liebesverbot are set in a castle-like format.