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91.
作为破坏性最强的海洋灾害,风暴潮灾害每年都给我国沿海地区造成了巨大的经济损失,运用科学的方法模型合理预测风暴潮灾害经济损失对指导沿海地区的防灾减灾工作意义深远。本文基于风暴潮灾害的成灾特点建立了风暴潮灾害直接经济损失预评估指标体系,由于评估指标数据高度非线性,采用核主成分分析(KPCA)对高维非线性数据进行降维优化,并利用径向基函数(RBF)神经网络对降维后的数据进行训练,从而实现对风暴潮灾害直接经济损失的预测。选取广东省1996—2018年的32个风暴潮灾害损失样本对模型进行仿真测试,结果表明,KPCA-RBF预测模型集成了核主成分分析和径向基函数神经网络的优势,预测结果精度高,学习收敛速度快,对风暴潮灾害数据序列有较好的非线性拟合能力。 相似文献
92.
AbstractWith the large-scale development and utilization of ocean resources and space, it is inevitable to encounter existing submarine facilities in pile driving areas, which necessitates a safety assessment. In this article, by referring to a wharf renovation project as a reference, the surrounding soil response and buried pipe deformation during pile driving in a near-shore submarine environment are investigated by three-dimensional (3D) numerical models that consider the pore water effect. Numerical studies are carried out in two different series: one is a case of a single pile focusing on the effect of the minimum plane distance of the pile–pipe, and the other is a case of double piles focusing on the effect of the pile spacing. 相似文献
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94.
长江口淡水端淡、盐水混合表层pCO2的急剧变化及其影响机制 总被引:4,自引:0,他引:4
根据2004年5月长江口淡水端淡、盐水混合初期表层水二氧化碳分压(pCO2)的实测数据,结合水文、化学和生物等要素的同步观测资料,对pCO2的变化及其影响因素进行了研究。研究结果表明:在长江口淡水端盐度0~15的淡、盐水混合初期,表层水pCO2由3 500μatm左右大幅度下降至约1 000μatm。生源要素的补充使生物活动的急剧增加是pCO2以对数形式大幅度降低的主要原因,这一性质显著体现的拐点为(S<0.6,50<浊度<110)这一范围。同时由于生物活动和物理混合作用的分别控制,使得长江口淡水端淡、盐水混合初期表层水碱度与盐度呈二次抛物线关系,拐点处的盐度约为0.6。 相似文献
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96.
Cynthia F. Lewis Stopher L. Slade Kerry E. Maxwell Thomas R Matthews 《新西兰海洋与淡水研究杂志》2013,47(1):271-282
Commercial fishers report finding their lobster traps often great distances from their original location following major hurricanes. But traps also move during lesser wind events, such as during winter cold fronts. To assess trap impact on coral communities following winter storms, lobster traps were placed in hardbottom and reef habitats commonly used by commercial fishers in the Florida Keys, United States. Trap movement, percentage benthic faunal cover, and benthic faunal damage were assessed after 26 wind events occuring over three winters. Traps moved when storms with sustained winds greater than 15 knots (27.8 km/h) persisted for more than 2 days. Winter storms above this threshold moved buoyed traps a mean (±SE) distance of 3.63 ± 0.62 m, 3.21 ± 0.36 m, and 0.73 ± 0.15 m per trap and affected a mean area of 4.66 ± 0.76 m2, 2.88 ± 0.29 m2, and 1.06 ± 0.17 m2, per trap at 4‐m, 8‐m, and 12‐m depths, respectively. Unbuoyed traps, simulating derelict traps, moved a mean distance of 0.43 ± 0.08 m and 0.44 ± 0.02 m, and affected a mean area of 0.77 ± 0.06 m2 and 0.90 ± 0.08 m2 per trap at 4‐m and 8‐m depths, respectively. Injuries caused by trap movement included scraped, fragmented, and dislodged sessile fauna, resulting in significant damage to stony coral, octocoral, and sponges. Overall, sessile fauna cover along the trap movement path was reduced from 45% to 31%, 51% to 41%, and 41% to 35% at the 4‐m, 8‐m, and 12‐m sites, respectively. Because of the large numbers of traps deployed and reported lost each season, damage to sessile fauna and loss of benthic faunal cover caused by traps needs to be considered to effectively protect coral reefs and manage essential fishery habitat in the future. 相似文献
97.
Solomon Assefa Clive Mc Cann Jeremy Sothcott 《Marine Georesources & Geotechnology》2013,31(2):119-140
Abstract There are few published seismic (P- and S-waves) properties for seafloor bedrocks. At low pressures (1 to 10 MPa), velocities and attenuations are determined mainly by open microcracks. At higher pressures, the microcracks close, and the velocities and attenuations depend primarily on the matrix porosity. We have investigated both the relationships between the acoustic, petrophysical, and geological properties of the rocks at 40 MPa pressure and the effect of microcracks on the acoustic properties at 10 MPa pressure. In this paper we discuss the former; the latter will be discussed separately. P- and S-wave velocity and attenuation measurements were carried out on a suite of seabed sedimentary and igneous rocks at effective pressures from 10 to 40 MPa at ultrasonic frequencies. The porosities and permeabilities of the rocks ranged from 0% to 32% and 0 to 110 mDarcy, respectively. Characterization of the rocks revealed that most of the sandstones have a substantial clay content (kaolinite, illite, and chlorite) and fractures. Most of the igneous rocks are chloritized. The seismic properties of the rocks are markedly lower than those of similar continental rocks because of the microporosity formed by the alteration of feldspars, micas, and mafic minerals to clays (e.g., chloritization of pyroxenes) and the corresponding reduction of the elastic moduli. The results of this study suggest that the values of velocities and quality factors used for ocean acoustic propagation models are lower than normally assumed. 相似文献
98.
在台风风暴增水过程中,风应力占主要作用,气压项的作用要上对较小,许多风暴潮预报模式中气压项被忽略。本文在建立台湾海峡风暴潮预报模型的基础上峄台风气压项作用进行了模拟,结果发现在台湾海峡狭长的海域内,台风气压项的作用表现得较为特殊,在台风风暴潮模拟过程中,应考虑其贡献及大小。 相似文献
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100.
Alexander Callaway Jennifer Smyth Craig J. Brown Rory Quinn Matthew Service David Long 《Estuarine, Coastal and Shelf Science》2009,84(3):409-422
The Irish Sea, like many marine areas, is threatened by anthropogenic activities. In particular the Pisces Reef system, a series of smothered rocky reefs are subject to fishing pressures as a result of their position within a Nephrops norvegicus fishery. In an area of sediment deposition and retention the reefs modify the environment by increasing the energy of near-bottom currents which results in localised scouring. This is the first study to attempt to characterise and investigate the ecological functioning of the Pisces Reef system. A multidisciplinary approach was essential for accurate investigation of the area. To facilitate more effective management of the benthic habitats of the Reef system, this study integrates acoustic, seismic, grab sampling and video ground-truthing methods for benthic habitat discrimination. Orientation of the scour hollows also suggest that seabed features could be used to infer dominant flow regimes such as the Irish Sea Gyre. The data revealed significant geology–benthos relationships. A unique biotope was described for the reef habitat and it was demonstrated that scouring may influence community composition through disturbance mechanisms. This study provides preliminary information required for management of a unique habitat within a uniform region. 相似文献