海平面上升的海岸形态响应研究方法与进展   总被引：12，自引：2，他引：12  

李恒鹏  杨桂山 《地球科学进展》2000,15(5):598-603

海岸带是人口最稠密的地带,全世界几乎一半的人口生活在沿海地区[1](根据UNCEDDE的定义,以距海岸线150 km计)。受全球变化,尤其是21世纪海平面加速上升的影响,海岸将发生复杂的形态响应过程,包括海岸侵蚀、滩地淹没和湿地沉积平衡的调整等,从而危害人类的生存和发展,引起世界沿海各国政府和科学界的广泛关注。从海平面上升海岸响应历史记录研究、海岸均衡剖面研究和形态响应模拟研究三个方面概述了海平面上升海岸形态响应的国内外研究进展,并对各种研究方法的适用范围、优点及局限性进行了讨论。  相似文献   

Structural,dynamic and anthropic conditions that trigger the emergence of the levee effect: insight from a simplified risk-based framework     

Claudia D’Angelo  Aldo Fiori 《水文科学杂志》2020,65(6):914-927

ABSTRACT

Levees are the most common structural solution to prevent flooding, reduce damage and generate benefits through more investment/economic activity in floodplain areas. While being relatively easy to build, levee effectiveness can be compromised by poor design and substandard construction methods and maintenance, thus increasing failure probability. Further, levees might increase societal vulnerability by instilling a sense of safety, the so-called “levee effect”. To cope with these phenomena, we develop a risk-based framework that quantifies residual risk under levee breaching and the levee effect, by disentangling its structural, dynamic and anthropic components, thus contributing to a better understanding of the phenomena at different spatial scales and the definition of flood risk policies. Through an illustrative example, we show how residual risk might become larger than under natural conditions, as function of the scale of interest, e.g. an area, a line at a given distance from the river, or a point within the floodplain.  相似文献   

Dam breach simulations with multiple breach locations under wind and wave actions     

Zhengang Wang  David S. Bowles 《Advances in water resources》2006

Multiple breaches of a dam resulting from wind-generated waves and wave overtopping are studied for a hypothetical long non-cohesive earthen dam with an uneven crest. Both wind speed and direction affect breach locations and outflow for a particular reservoir surface geometry. Locations on the dam with longer fetches along the wind direction are more subject to wave overtopping and breaching than other locations. Higher wind speeds lead to wave overtopping and dam breaches under larger freeboards than lower wind speeds. For a specified inflow hydrograph and spillway configuration, there exists a location at which the smallest estimated peak outflow occurs among all possible breach locations and the pool drops too quickly for additional breaches to develop. Using this location for a fuse plug or a pilot channel could minimize downstream impact, perhaps as an interim or emergency measure for a dam with inadequate spillway capacity.  相似文献   

The formation and closure of the Big Breach of Sacalin spit associated with extreme shoreline retreat and shoreface erosion     

Florin Iulian Zăinescu  Alfred Vespremeanu-Stroe  Florin Tătui 《地球表面变化过程与地形》2019,44(11):2268-2284

We document a case of exceptionally large natural breaching of a sandy spit (Sacalin spit, Danube Delta) using multiannual to seasonal surveys of topography and bathymetry on successive cross-barrier and shoreface profiles, LiDAR data, satellite imagery, and wind and wave data. The large breach, which quickly reached 3.4 km in May 2014, is attributed to morphological preconditioning of the narrow (50–150 m) barrier, which was susceptible to breaching even during moderate storm conditions. The event switched the barrier's decadal evolution from low cross-shore transport to high cross-shore transport over the barrier, which is an order of magnitude larger than during the non-breach period. Upper shoreface erosion, as indicated by the extensive erosion down to −4 m, indicates that this zone is a significant source for the rebuilding of the barrier. Barrier recovery and widening trigger a negative feedback which limits the back-barrier sediment transfer. As a result, back-barrier deposition decreases whilst the barrier aggradation through overwash becomes more frequent. The Big Breach (TBB) closed naturally in three years. The very high deposition rate of sediment in the breach is a testimony of the high sediment volumes supplied by the longshore transport and the high sediment released through shoreface retreat, and resulted in widening the barrier to a maximum of 1 km. Since the newly-formed barrier shoreline retreated 500 m, this reveals that barrier breaching is an important mechanism which significantly accelerates the landward migration of the barrier system and is a proof of the highly non-linear morphodynamics involved in the barrier island translation. © 2019 John Wiley & Sons, Ltd.  相似文献   

堰塞坝漫顶溃决过程溃口纵向下切与溯源     

刘杰  李丽华  林跃水  陈伟  李晓明 《吉林大学学报(地球科学版)》2020,50(6):1795-1803

为进一步了解堰塞坝溃坝过程,开展了9组水槽模型试验,对溃口纵向下切和溯源发展过程进行了系统分析,并讨论了上溯源点移动速度与溃口水深之间的关系。研究发现：非黏性堰塞坝溃坝过程中,冲刷面与底床的夹角时刻发生变化,上、下溯源点位置不固定但也不能完全发展到坝踵;上、下坡面坡度增大到最大值1：1.5时,下溯源点到下游坝趾的最大距离与坝体沿水流方向长度的比值（x_p^*/x_d^*,反映下溯源点最终相对位置）对应降低到最小值0.24和0.18;坝体相对尺寸从1减小到1/2时,x_p^*/x_d^*值从0.38增大到0.47。上溯源点的无量纲移动速度是不断变化的,在无量纲时刻为0.13时,其x,y分量分别达到峰值0.94和0.32;上溯源点处溃口水深出现时刻相对移动速度峰值点出现时刻有延迟,大概延迟0.04个无量纲时间。  相似文献   

堤防历史口门部位渗流控制研究     

李金都  周志芳  李海波  李清波  高正夏 《岩土力学》2006,27(1):17-22

堤防历史口门部位是堤防的重大隐患,以黄河荆隆宫历史口门堤段为实例,通过公式解析法和有限元法进行了渗流计算,并对堤防历史口门部位的渗流控制措施进行了分析,研究结果表明,黄河荆隆宫历史口门堤段加固设计方案可选择减压井方案,为堤防加固设计提供了重要的依据。  相似文献   

全球多分辨率数据模型的构建与快速显示   总被引：8，自引：2，他引：6  

童晓冲  贲进  张永生 《测绘科学》2006,31(1):72-74,79

在总结并分析国内外已有的多种全球数据浏览和显示系统的基础上,采用了全球空间四叉树模型与“视点相关”的处理方式,并将多线程理论有效地应用到超大数据的管理与显示中,建立了合理的多线程访问机制,利用金字塔瓦片数据集管理影像与DEM数据,实现了局域网内的分布存储与分发,并开发了全球海量数据管理客户端实验系统GlobalView。  相似文献   

战场环境可视化中多源遥感影像数据处理     

廖云  余旭初  杨国鹏 《测绘科学技术学报》2006,23(1):41-43

介绍了将多源遥感影像数据应用于战场环境可视化之前的主要预处理方法,如影像金字塔生成、纹理数据结构准备、纹理快速调用等.该过程中所用到的小波变换、四叉树数据结构与细节层次算法等关键技术,能够有效地提高战场建模的真实感和效率.  相似文献   

Fish recruitment into a South African temporarily open/closed temperate estuary during three different hydrological mouth phases     

GP Tweddle  PW Froneman 《African Journal of Marine Science》2017,39(2):203-209

Quantitative recruitment of ichthyofauna into a South African temporarily open/closed estuary (TOCE) was investigated during three distinct hydrological phases: closed overwash, open outflow and tidal mouth conditions. Maximum recruitment densities occurred during outflow conditions and declined when the system became tidally inundated. Recruitment densities were lowest during overwash events. Selective diel variation was evident, with higher night-time densities for each phase. This study highlights the importance of seasonal timing and duration of open conditions and overwash events for structuring ichthyofaunal community composition of southern African TOCEs.  相似文献   

Infidelity and the Internet: The Geography of Ashley Madison Usership in the United States          下载免费PDF全文

Michael L. Chohaney  Kimberly A. Panozzo 《Geographical review》2018,108(1):69-91

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