波浪溢流作用下海堤内坡高性能加筋草皮护坡防侵蚀特征研究

基于1∶1的大型水槽试验结果,分析了波浪溢流过程中位于海堤内坡的高性能加筋草皮护面的侵蚀特征。试验观察表明试验期间有一定土壤的损失,但护坡无明显的破坏;土面高度测量表明,当土壤流失发展到一定深度后,如果水动力强度变化不大,侵蚀趋于逐渐停止,这种现象称为侵蚀上限;结合试验现象对侵蚀上限进行了初步解释,并讨论了侵蚀上限达到前的侵蚀速率特征;植株密度监测表明,试验期间的草茎密度基本不变,草叶密度在开始几次试验期间持续减小,而后达到一个稳定值,这对于海堤的可持续防护有重要意义。研究成果能够为波浪溢流期间海堤内坡防御的相关研究和工程措施提供参考依据。     

A simplified hindcast method for the estimation of extreme storm surge events in semi-enclosed basins

Human presence, coastal erosion, and tourism activities are increasing the attention to coastal flooding risk. To perform risk assessments, long time series of observed or hindcast wave parameters and tide levels are then necessary. In some cases, only a few years of observation are available, so that observed extreme data are not always representative and reliable. A hindcast system aimed to reconstruct long time series of total tide levels may be of great help to perform robust extreme events analysis and then to protect human life, activities as well as to counteract coastal erosion by means of risk assessments. This work aims to propose a simplified method to hindcast storm surge levels time series in semi-enclosed basins with low computational costs. The method is an extension of a previous work of some of the authors and consists of a mixed approach in which the estimation of storm surge obtained by using the theory of linear dynamic system is corrected by using a statistical method. Both steps are characterized by low computational costs. Nevertheless, the results may be considered reliable enough also in view of the simplicity of the approach. The proposed method has been applied to the Manfredonia case study, a small village located in the Southern Adriatic Italian coast and often prone to coastal flooding events. The comparison of extreme events estimated on the basis of hindcast levels time series is satisfactorily similar to those estimated on the basis of observed tide series.     

塔西北下寒武统风暴活动特征及其沉积学响应

在塔西北阿克苏露头区发育多套类型不同的下寒武统肖尔布拉克组风暴岩,它们宏观上与微生物丘混生或共生,微观上可见不同类型的微生物结构,但与此相关的研究甚少。以露头观察和室内鉴定为基础,在苏盖特布拉克地区和昆盖阔坦地区划分出4类8种各具特色的微生物丘—风暴岩沉积序列,并归纳总结了塔西北地区下寒武统肖尔布拉克组风暴沉积模式,认为其发育位置和沉积特征主要受控于“三面”,包括平均海平面(MSL)、正常浪基面(FWB)和风暴浪基面(SWB);“四期”,包括平静期、高峰期、衰减期与停息期;“五流态”,包括风暴涡流、风暴下部回流(包括风暴碎屑流和风暴浊流)沉积与风暴上部回流(包括风暴漫流和风暴潮流)。另外古风暴中心的发育位置也可影响风暴沉积特征。最后在前人研究的基础上,对“贫乏骨骼的风暴海”的形成条件进行探讨。     

长春台磁暴特征研究

依据长春地震台记录的磁暴资料,系统总结了第19、20、21三个太阳活动周磁暴特征,并对全球M_s≥7.8级地震的发生与太阳黑子活动、磁暴的关系进行了初步探讨。     

局地强风暴云团与中尺度锋面波动

本文分析了1982—1988年2—5月份的41例与中尺度锋面波动相关联的局地强风暴云团的活动和演变特征，给出了其强盛期天气系统配置模式及其在天气尺度云系演变中的表现型式，最后对其移动做了一般性讨论。     

The structure of the mid- and high-latitude ionosphere during the November 2004 storm event obtained from GPS observations

GPS data from the International GNSS Service (IGS) network were used to study the development of the severe geomagnetic storm of November 7–12, 2004, in the total electron content (TEC) on a global scale. The TEC maps were produced for analyzing the storm. For producing the maps over European and North American sectors, GPS measurements from more than 100 stations were used. The dense network of GPS stations provided TEC measurements with a high temporal and spatial resolution. To present the temporal and spatial variation of TEC during the storm, differential TEC maps relative to a quiet day (November 6, 2004) were created. The features of geomagnetic storm attributed to the complex development of ionospheric storm depend on latitude, longitude and local time. The positive, as well as negative effects were detected in TEC variations as a consequence of the evolution of the geomagnetic storm. The maximal effect was registered in the subauroral/auroral ionosphere during substorm activity in the evening and night period. The latitudinal profiles obtained from TEC maps for Europe gave rise to the storm-time dynamic of the ionospheric trough, which was detected on November 7 and 9 at latitudes below 50°N. In the report, features of the response of TEC to the storm for European and North American sectors are analyzed.     

99洪水和对进一步治理太湖的探讨

1999年太湖流域发生了特大洪水,太湖最高洪水位达5.08m,创历史新高.文中分析了1999年洪水的雨情、水情及其特点.阐述了已建治理太湖工程的防洪作用和减灾效益,并对太湖流域的进一步治理作了探讨.     

Pyroclastic phases of a rhyolitic dome-building eruption: Puketarata tuff ring,Taupo Volcanic Zone,New Zealand

The 14 ka Puketarata eruption of Maroa caldera in Taupo Volcanic Zone was a dome-related event in which the bulk of the 0.25 km³ of eruption products were emplaced as phreatomagmatic fall and surge deposits. A rhyolitic dike encountered shallow groundwater during emplacement along a NE-trending normal fault, leading to shallow-seated explosions characterised by low to moderate water/magma ratios. The eruption products consist of two lava domes, a proximal tuff ring, three phreatic collapse craters, and a widespread fall deposit. The pyroclastic deposits contain dominantly dense juvenile clasts and few foreign lithics, and relate to very shallow-level disruption of the growing dome and its feeder dike with relatively little involvement of country rock. The distal fall deposit, representing 88% of the eruption products is, despite its uniform appearance and apparently subplinian dispersal, a composite feature equivalent to numerous discrete proximal phreatomagmatic lapilli fall layers, each deposited from a short-lived eruption column. The Puketarata products are subdivided into four units related to successive phases of:(A) shallow lava intrusion and initial dome growth; (B) rapid growth and destruction of dome lobes; (C) slower, sustained dome growth and restriction of explosive disruption to the dome margins; and (D) post-dome withdrawal of magma and crater-collapse. Phase D was phreatic, phases A and C had moderate water: magma ratios, and phase B a low water: magma ratio. Dome extrusion was most rapid during phase B, but so was destruction, and hence dome growth was largely accomplished during phase C. The Puketarata eruption illustrates how vent geometry and the presence of groundwater may control the style of silicic volcanism. Early activity was dominated by these external influences and sustained dome growth only followed after effective exclusion of external water from newly emplaced magma.     

An evaluation of the role played by remote sensing technology following the World Trade Center attack

Remote sensing technology has been widely recognized for contributing to emergency response efforts after the World Trade Center attack on September 11th, 2001. The need to coordinate activities in the midst of a dense, yet relatively small area, made the combination of imagery and mapped data strategically useful. This paper reviews the role played by aerial photography, satellite imagery, and LIDAR data at Ground Zero. It examines how emergency managers utilized these datasets, and identifies significant problems that were encountered. It goes on to explore additional ways in which imagery could have been used, while presenting recommendations for more effective use in future disasters and Homeland Security applications. To plan adequately for future events, it was important to capture knowledge from individuals who responded to the World Trade Center attack. In recognition, interviews with key emergency management and geographic information system (GIS) personnel provide the basis of this paper. Successful techniques should not be forgotten, or serious problems dismissed. Although widely used after September 11th, it is important to recognize that with better planning, remote sensing and GIS could have played an even greater role. Together with a data acquisition timeline, an expanded discussion of these issues is available in the MCEER/NSF report “Emergency Response in the Wake of the World Trade Center Attack; The Remote Sensing Perspective” (Huyck and Adams, 2002)