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91.
现代黄河三角洲滨浅海区的灾害地质   总被引:8,自引:4,他引:8  
利用卫星遥感、测深、浅地层剖面及钻孔资料研究了黄河三角洲海岸及近海海洋灾害地质,编制了黄河三角洲海洋灾害地质图。黄河三角洲海岸灾害地质以海岸侵蚀为主,根据1976—2001年海岸的变化速率,可将海岸分为快速侵蚀海岸、中等程度侵蚀海岸、稳定海岸和淤积海岸四类,快速侵蚀海岸和中等程度侵蚀海岸长期以来遭受侵蚀。灾害地质因素有浅层气、灾害地貌、活动断层、海底滑坡、底辟、隆起脊、埋藏冲沟一古河道。浅层气主要分布在老黄河口附近渤海海底,近岸少见。浅层灾害地貌主要分布在三角洲前缘斜坡上的扰动区。扰动区位置在整个三角洲上变动明显,有向岸移动的趋势,斜坡坡度减小,扰动强度减弱。底辟除了发生在废弃三角洲侵蚀区外,还发生在三角洲外的渤海海底下部。隆起脊位于黄河口东部渤海海底,沿NE—SW方向发育,顺隆起脊发育活动断层。  相似文献   
92.
A numerical model of shoreline change of sand beaches based on long-term field wave data is proposed, the explicit and implicit finite difference forms of the model are described, and an application of the model is presented. Results of the application indicate that the model is sensitive to the order of the input wave data, and that the effects of long-term wave series and the effects of the mean annual wave conditions on the model are different. Instead of a single wave condition, the wave series will make the calibration and the verification of the model more practical and the results of the model more reasonable.  相似文献   
93.
The reproductive biology of Acanthopagrus butcheri has been studied in the permanently open Swan River and intermittently open Moore River estuaries on the lower west coast of Australia (31--32 °S) and in the permanently open Nornalup Walpole and normally closed Wellstead estuaries on the southern coast of Western Australia (34--35 °S). Trends exhibited by gonadosomatic indices, gonadal maturity stages and the sizes and developmental stages of the oocytes demonstrate that A. butcher typically spawns in spring and early summer. However, spawning occurred in salinities ranging from as low as 3.5-8 g L–1 in the Moore River Estuary to as high as 41-45 g L–1 in the Wellstead Estuary. Furthermore, water temperatures during spawning were greater in the two northern estuaries (19.7--28.5 °C) than in the two southern and cooler estuaries (17.5--23.4 °C). Histological studies strongly indicate that A. butcheri spawn more than once in a breeding season and demonstrate that the development of its oocytes exhibits group synchrony sensu de Vlaming (1983). The ages and total lengths at which, on average, female and male A. butcheri both first attain maturity in the Swan River Estuary were ca 2 years and ca 215 mm. However, the age at which individual fish in that system reach maturity was influenced by body size. This suggests that the attainment of first maturity at an older age but smaller length in the Moore River and Nornalup Walpole estuaries than is the case in the Swan River Estuary is a consequence of the slower growth rates of A. butcheri in those estuaries. The combination of the young age (ca 2 years) but small length (ca 145 mm) at which maturity is first attained in the Wellstead Estuary could have resulted from selection pressures brought about by high mortality rates and/or heavy fishing pressure in this estuary. The mean fecundity of A. butcheri, based on the combined number of yolk vesicle and yolk granule oocytes found in ovaries just prior to the onset of spawning, was 1580 × 103. The significance of the sizes at first maturity, minimum legal length for capture, mesh selectivity data and closure of certain regions of estuaries to fishing for the management of the recreational and commercial fishery for A. butcheri is discussed.  相似文献   
94.
河北沿海海侵灾害初探   总被引:4,自引:1,他引:4  
文中以包含海进、海岸侵蚀和海水入侵的广义“海侵”概念,论述河北沿海地区海侵现状及其危害,探讨海侵产生的自然原因和人为活动的影响,在此基础上,评估海侵发展趋势。  相似文献   
95.
While natural marine habitats with motion capabilities, e.g., kelps and seaweeds, have been studied alongside their associated fouling communities, little is known of the effect of motion on the communities of floating artificial habitats such as buoys, rafts, and pontoons, particularly in tropical systems. Hydrodynamic features greatly differ between floating and fixed artificial substrata, which in turn affect the structure of their associated communities. This study tested the hypothesis that floating and fixed artificial installations in a tropical reef system (Eilat, Red Sea) would support different benthic communities throughout space and time. Specifically, we examined differences in communities recruited onto settlement plates between floating and fixed installations deployed at three different sites, along a two-year monitoring period. The three sites exhibited distinct differences in species assemblages between the monitoring dates (6, 12, 18 and 24 months post deployment), mainly between the first and the last two dates. The average level of dissimilarity between floating and fixed installations increased over time at all sites. Over 50% of the dissimilarity between the floating and fixed installations resulted from five taxonomic groups i.e., bryozoans, bivalves, barnacles, sponges, including the amount of bare space on the settlement plates. The contribution of these groups to the dissimilarity changed both temporally within each site, and spatially among sites. The observed differences were related to the hydrodynamic characteristics of floating and fixed habitats, interacting with biotic features such as predation, successional processes and seasonality; and abiotic features including small-scale spatial changes, light, and position in the water column.  相似文献   
96.
提出了一个改进的经验公式,用以计算围垦工程引起的淤泥质海岸多年冲淤演变。该经验公式假定在年时间尺度上,地形变化与潮流场变化具有密切联系。引入了一个冲刷折减系数,将传统公式的适用范围从淤积计算拓展到可以同时计算冲刷和淤积。建立了冲淤率年际变化与水深变化之间的关系式,可节省计算时间。将改进公式应用于江苏沿海小庙洪水道,较好地复演了边滩围垦工程影响下周边地形在3年时间内的演变,表明所改进的公式具有一定的可靠性。  相似文献   
97.
在分析山东南部海岸几十年来的地形观测资料的基础上,运用砂质海岸等深线变化预测理论,建立该区的岸滩侵蚀演变预测模型,研究了该区域岸滩演变规律。实测资料验证表明:预测结果合理,基本反映了本区岸滩演变的特征。  相似文献   
98.
基于2014—2018年NOAA/AVHRR遥感数据,在山东半岛海域选取6条剖面,结合海表温度和表层悬浮体的时空变化特征,详细研究了山东半岛沿岸流的年周期变化规律与移动路径。研究结果表明,山东半岛沿岸流年周期变化可分为4个阶段:成长期(10—12月)时开始形成于黄河口附近,沿莱州湾南部向东运移;强盛期(次年1—3月)时山东半岛沿岸流完全成型,扩散带最宽,鼎盛时期北部可以至38°N附近,东部可以至123°E附近,在35°~36°N附近分成NE—SW向的2个分支,主干部分最远可到达胶州湾东部海域,余流沿岸向西南方向转折;衰退期(4—6月)时沿岸流强度减弱,只在山东半岛北部和东部小范围内有微弱的显示;消亡期(7—9月)时基本消失。山东半岛沿岸流在冬季时对悬浮体扩散具有强烈的驱动作用,使其在黄河口南侧与山东半岛北岸-成山头东部海域分别形成呈“弧形”和“条带状”分布的2个高浓度区域。  相似文献   
99.
This paper involves a collection and communication of important knowledge about and experiences with outdoor recreation monitoring in Nordic coastal and marine areas. This is a topic that so far has received little attention, especially among researchers and practitioners working with outdoor recreation monitoring in Nordic coastal and marine areas, who are in need of knowledge on the topic in order to advance monitoring activities and procedures. To remedy this situation, the purpose of this paper is to provide a knowledge base by listing and describing central literature contributions with important insight into outdoor recreation monitoring in Nordic coastal and marine areas. More specifically, this includes information about: (a) where important knowledge about outdoor recreation monitoring in Nordic coastal and marine areas can be found, (b) who the main contributors are and (c) what monitoring knowledge that has been reported so far. The paper also examines what tasks lie ahead for researchers and area managers in order to improve knowledge about outdoor recreation monitoring in Nordic coastal and marine areas. The paper is a central contribution and addition to manuals on outdoor recreation monitoring that are currently available in the Nordic countries.  相似文献   
100.
为了弄清江苏沿海滩涂利用模式分布情况,定量分析其时空变化趋势,本文基于Google Earth Engine云计算平台和Landsat卫星遥感影像数据,结合随机森林分类方法,通过机器学习建立了滩涂利用模式自动识别分类方法,样本训练后识别准确率达93%以上.利用该方法提取了2002年、2014年和2019年江苏沿海的土地...  相似文献   
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