Automated suitable drainage network extraction from digital elevation models in Taiwan's upstream watersheds     

Wen‐Tzu Lin  Wen‐Chieh Chou  Chao‐Yuan Lin  Pi‐Hui Huang  Jing‐Shyan Tsai 《水文研究》2006,20(2):289-306

Automatically extracting drainage networks from digital elevation models coupled with the constant stream threshold value is a regular method. These extracted networks can be verified by comparing the channel initiation points with those from real networks. From the results analysed, the differences in channel initiation points will affect the network geometries, geomorphological indices and hydrological responses. This paper develops two automatic algorithms, the headwater‐tracing method and the fitness index, to trace the flow paths from headwaters to the outlet and to calculate the reasonable stream threshold. Instead of the method determined by trial and error or field survey, the accurate channel initiation points can be obtained from airborne photographs coupled with high‐resolution SPOT images for suitable drainage network extraction. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Factors influencing hazard management by municipalities: The case of coastal communities     

《Global Environmental Change》2022

As climate and anthropogenic changes increase the vulnerability of coastal areas around the world, the threat (and reality) of coastal hazards grows. These threats arise particularly at a local level, calling out for more knowledge on how to best support coastal municipalities to deal with natural and human-induced hazards. This study seeks to add to the understanding through an examination of local-level experience with hazard planning and responses carried out by coastal municipalities, producing insights on how to reduce their vulnerability and support their resilience. It explores the factors influencing coastal municipalities’ management of relevant hazards to achieve comprehensive multi-hazard risk reduction and adaptation. We do so through a national survey of Canada’s coastal municipalities which assessed experience with hazards, risk perception, hazard prioritization, and the extent and specifics of hazard responses. We characterize the determinants of coastal municipalities’ behaviour and intervening factors, and conduct regression analyses to explain coastal municipalities’ risk perception, hazard prioritization, implementation of management processes for dealing with hazards, and the number of implemented or planned hazard responses. Six key factors were identified that influence hazard responses at the municipal level: experience with hazards; competing priorities; hazard visibility; access to resources (financial and technical capacity) and governance (institutional setting and political capacity). We conclude that municipal hazard responses can be reinforced by increasing the effectiveness of risk communication, promoting participatory processes, providing support for municipalities’ identified needs and priorities, ensuring municipalities have access to relevant information and expertise, and implementing integrated coastal governance and management.  相似文献   

Approximating peak responses in seismically isolated buildings using generalized modal analysis     

Tracy C. Becker  Stephen A. Mahin 《地震工程与结构动力学》2013,42(12):1807-1825

Although the ability to simulate accurately the detailed behavior of nonlinear isolation bearings and the effects of this nonlinearity on dynamic response of the isolated building is desirable, such detailed analyses are not feasible during initial design stages when bearing properties are being selected. However, it would be very beneficial to be able to estimate accurately key engineering demand parameters at the early stages of design to understand the dynamic response characteristics of the isolated structure and to balance and optimize the bearing and structural characteristics to achieve the performance goals set for the building. Unfortunately, classical modal response spectrum analysis methods do not provide accurate results for problems with large, nonclassical damping, as is characteristic of isolated buildings. To find a method capable of predicting peak building responses even with large nonclassical damping, generalized modal response spectrum analysis is implemented. The responses of several buildings having different heights and isolated by linear viscous as well as triple friction pendulum and single friction pendulum isolation systems are investigated. Generalized modal response spectrum analysis methods were found to give significantly better predictions for all systems compared with classical methods. The behavior of buildings isolated with single friction pendulum systems exhibiting sudden changes in stiffness could not be well predicted by either general or classical modal response spectrum analysis when effective damping was increased. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

基于生成对抗网络的建筑物损毁检测EI北大核心CSCD     

葛小三  陈曦  赵文智  李瑞祥 《测绘学报》2022,51(2):238-247

建筑物作为自然灾害中最受影响的承灾体之一,其损毁信息的准确提取对灾后应急救援具有十分重要的意义。本文借鉴多模态的思想,提出了一种自动检测损毁建筑物的recursive-generative adversarial networks(RS-GAN)方法,将损毁建筑物检测分为灾前建筑物识别和灾后损毁建筑物检测两个任务,且分别在两个GAN分支中完成。RS-GAN加入联合损失函数将两个GAN分支进行连接,充分利用两个任务之间的潜在互利性提升检测效果。RS-GAN利用第1条GAN分支识别建筑物灾前形状与位置,并将识别结果作为第2条GAN分支的输入进行损毁建筑物检测任务,从而使检测结果具有更清晰的轮廓。该方法为端到端模型,在不需要过多的人工干预情形下,实现了损毁建筑物的自动检测。为了验证RS-GAN模型的效果,在圣罗莎和密苏里两个数据集上进行了测试。试验结果表明,RS-GAN方法拥有更好的检测性能,在圣罗莎数据集上的总体精度和平均精度分别达到了0.90和0.86。  相似文献   

聚苯乙烯和四溴联苯醚对黑褐新糠虾抗氧化防御系统的联合效应     

陈钮振  李正炎 《中国海洋大学学报(自然科学版)》2022,52(1):78-87

本文以黑褐新糠虾(Neomysis awatschensis)为受试生物,分别研究两者单独及联合暴露21 d后的氧化应激效应,并结合综合生物标志物响应(Integrated Biomarker Response,IBR)评估其毒性。结果表明:PS单独暴露时,过氧化氢酶(Catalase,CAT)、谷胱甘肽硫转移酶(Glutathione S-transferase,GST)、超氧化物歧化酶(Superoxide dismutase,SOD)和谷胱甘肽过氧化物酶(Glutathione peroxidase,GPX)活性随暴露浓度升高被显著抑制,丙二醛(Malondialdehyde,MDA)含量随暴露浓度增加逐渐上升,而谷胱甘肽(Glutathione,GSH)含量仅在97.4μg·L^-1暴露下显著上升;BDE-47单独暴露时,CAT、GST和GSH含量均被抑制,MDA和GPX活性仅在较高浓度下被显著诱导,SOD活性在低浓度被诱导,在最高浓度下恢复至空白水平。联合暴露时,CAT和SOD活性随PS投加浓度升高表现出先诱导后抑制的效应,且均显著高于BDE-47单独暴露组,MDA含量随PS投加浓度升高表现出诱导效应。GST和GPX活性与空白水平相近,低浓度PS暴露组中的GSH含量也有相似的变化规律。可见,PS能减缓BDE-47对黑褐新糠虾抗氧化防御系统的氧化胁迫,在低浓度PS联合暴露组中尤其显著。  相似文献   

中国大陆井水温对汶川8.0级、玉树7.1级、芦山7.0级和岷县6.6级地震响应特征的对比研究          下载免费PDF全文

张彬  刘耀炜  杨选辉 《地震工程学报》2013,35(3):535-541

收集和统计了2008年汶川MS8.0地震、2010年玉树MS7.1地震和2013年芦山MS7.0、岷县MS6.6地震引起的中国大陆井水温同震响应现象,分析了其特征。结果显示:这4次地震对中国大陆地下流体影响显著,井水温同震响应特征有很大差异,后三次水温同震响应范围、幅度和持续时间远不及汶川地震,即使震级相差不大的玉树和芦山地震,同震响应的特征也不尽相同。最后探讨了这种现象的成因机理。  相似文献   

全球气候变化对红树林生态系统的影响、挑战与机遇     

王友绍 《热带海洋学报》2021,40(3):1-14

红树林是以红树植物为主体的常绿灌木或乔木组成的潮滩湿地木本植物群落, 具有“四高”特性(高生产力、高归还率、高分解率和高抗逆性)的典型海洋生态系统; 目前, 全球约有红树林1700万公顷, 主要分布在南北半球25℃等温线内。红树林生态系统的净初级生产力高达2000gC·m^-2·a^-1, 具有高强度的物质循环、能量流动以及丰富的生物多样性, 对热带、亚热带海洋生态系统的维持与发展起到关键作用, 并在全球变化过程中扮演着十分重要的角色。近30年来, 全球气候变化已引起了国内外学者的极大关注。红树林生态系统位于热带、亚热带海岸潮间带, 是一个脆弱的、敏感的生态系统, 也是首先受全球气候变化影响的典型海洋生态系统之一。作为全球海岸带地区应对全球气候变化最为重要的生态屏障之一, 气候变化将严重影响着全球红树林的生存和分布方式。本文将从全球变暖、海平面上升、大气中CO₂浓度的增加和极端天气4个主要方面, 揭示全球气候变化对红树林生态系统的影响与变化特征, 阐述红树林对全球变暖、海平面上升、大气中CO₂浓度增加和极端天气响应与适应的生态学机制, 并简要概述了红树林在减缓全球气候变化危害中的重要作用。全球气候变化也将为红树林的研究、保护和发展带来机遇与挑战。  相似文献   

安装有防屈曲支撑建筑的地震模拟与经济性分析     

杨昌民  李宏男  牧野俊雄  郝晓燕 《地震学刊》2012,(4):423-428,435

结合防屈曲支撑拟静力实验的研究成果,用ABAQUS有限元软件模拟一栋建筑的地震反应。比较原设计结构与减少梁柱面积但安装有防屈曲支撑的减缩结构这2种方案下的地震响应,使两者的层间位移角相近并满足规范要求,进而做经济性对比。结果表明,防屈曲支撑可以有效地减小结构地震响应,并且先于梁柱破坏,保护主体结构安全;安装防屈曲支撑的结构在满足设计要求的同时,还可以节省建筑成本,缩短施工工期。  相似文献   

三维可视化技术在舟曲县城区灾后重建泥石流防治工程中的应用   总被引：1，自引：0，他引：1  

吴宏  董金义  李瑞冬  张华伟  尚海龙  曾建军 《冰川冻土》2013,35(2):383-388

结合舟曲县城区灾后重建泥石流防治工程相关数据, 采用3ds Max、 Maya等三维建模软件构建了泥石流防治工程三维模型, 基于Skyline三维GIS平台建立了灾后泥石流防治工程三维可视化场景.对三维可视化场景构建的关键技术、 三维空间数据处理、 三维模型制作和三维场景构建进行详细阐述, 最终建立的舟曲县城区灾后重建泥石流防治工程三维场景将直观、 逼真地显示舟曲县地形、 泥石流防治工程部署情况, 可为今后当地政府防灾减灾工作提供决策支持.此外, 应用目前先进的流体、 刚体动力学模拟软件对舟曲"8.8"特大山洪泥石流灾害过程进行三维动态模拟, 效果比较理想.  相似文献   

岩性及岩体结构对斜坡地震加速度响应的影响   总被引：1，自引：0，他引：1  

刘汉香  许强  侯红娟 《岩土力学》2013,34(9):2482-2488

斜坡岩体的岩性及岩体结构是斜坡在地震作用下产生变形破坏的主要控制因素。基于振动台模型试验,对4个斜坡模型探讨了这2个因素对斜坡地震动力响应的影响。岩性包括强度相对较高的硬岩和强度相对较低的软岩,对这两种岩性的斜坡又分别考虑了不含结构面的均质斜坡和含水平层状结构面的斜坡。基于传感器采集到的大量数据,以主频相近的天然地震波和10 Hz正弦波加载为分析工况,获得了以下几点认识：（1）4个模型斜坡坡面和坡内的水平向加速度均具有高程放大效应,尤其是软岩斜坡坡顶放大效应最显著;（2）软岩斜坡对水平向加速度的高程放大效应强于硬岩斜坡,尤其是在均质斜坡中表现最显著,均质软岩斜坡的高程放大效应呈现出明显的非线性特征;（3）当加载方向与水平层面平行时,含水平层状结构面的斜坡比均质斜坡产生了更强的高程放大效应,且在软岩斜坡中体现最显著;（4）岩性差异对斜坡水平向加速度高程效应的影响比结构差异的影响更为显著。研究结果为岩质斜坡的抗震设计提供了一定参考。  相似文献