Variability of river plumes off Northwest Iberia in response to wind events

The Western Iberian Buoyant Plume (WIBP) is a low-salinity lens formed by river discharge and continental run-off extending along the shelf off Northwest Iberia. The variability of this structure is evaluated with a numerical model forced by real meteorological data and climatologic river discharge during late 2002, when conditions were those of a typical autumn. The direction and intensity of the wind-induced Ekman transport, but also the previous conditions and the duration of the event are found to determine plume behavior. We have identified three characteristic situations: a) confinement of the plume to the coast during downwelling — southerly-winds, b) expansion of the plume during the declining phase of the downwelling event by relaxation of the wind, and c) expansion of the plume by upwelling — northerly-winds. The short time scale of the response of the plume (1–3 h) adds timing between wind events and the phase of the tide as an additional source of variability. In all cases the Iberian Poleward Current (IPC), a saltier and warmer poleward current flowing over the slope, responds as well to wind changes. Furthermore, our simulations illustrate how topography and differences in the river discharge induce local differences in dynamics. Comparisons to available observations show a reasonable model skill. Differences between wind measurements and wind forcing applied to the model appear to be a major source of uncertainty in model results.     

滨海公路辽河特大桥主桥总体结构静力分析

滨海公路辽河大桥主桥为主跨436m的钻石形双塔双索面钢箱梁斜拉桥.根据该桥的结构特点应用有限元结构分析程序对施工、成桥和运营阶段进行了总体结构静力分析,通过分析结果验证了结构设计的安全性.     

Developing a Sustainable Community-Based Aquaculture Plan for the Lagoon of CuyutlÀn through a Public Awareness and Involvement Process

This study presents evidence from the Cuyutlàn lagoon, which demonstrates that aquaculture can be socially acceptable, economically viable and environmentally friendly when consideration is first taken of the local circumstances and environment. This evidence was obtained through a user survey, which asked key questions of the local fishing community. These questions aimed to determine the desires and needs of the local community in the context of the local environment. The results from this survey of 56% of the fishing community were presented. The wishes of the fishing community are discussed and a compromise suggested for a sustainable aquaculture for the Cuyutlàn lagoon.     

中外斜坡堤胸墙波浪力计算对比

斜坡堤胸墙对于减轻越浪危害至关重要,国内外各胸墙波浪力计算方法的结果差异较大。基于国内外几种斜坡堤胸墙波浪力计算方法,结合工程案例和试验数据进行对比研究。结果表明:1)特定条件下,我国规范计算的水平波浪力压强分布高度远小于Jensen法和Pedersen法结果,后两法计算结果与实测高度一致。2)Jensen法和Pedersen法计算的水平波浪力及浮托力均比国内港工方法大,也大于实测值。3)港工规范计算的总水平波浪力比实测值小,其计算出的浮托力与实测值较为接近。4)Jensen法考虑了掩护棱体肩台高度的作用,Pedersen法考虑了掩护棱体肩台高度与宽度的影响。此二法考虑得相对全面,但其按深水波长计算0.1%超越概率的波浪力,计算结果偏于保守。5)建议重要工程以模型试验结果为准。     

软基处理技术在辽宁省滨海地区废弃盐滩中的综合应用

本文通过辽宁省滨海公路大连市金州北海至葫芦套段七顶山盐场废弃盐滩软基处理的施工,总结了抛石挤淤、堆载预压、强夯置换等软基处理方法在滨海地区软基处理中的综合应用、施工工艺、质量控制手段和质量检验方法。     

浅谈滨海公路沿海段路基防护

以滨海公路庄河段为例介绍了植草、干砌片石护坡、浆砌片石护坡及抛石等方法综合处理临海段路堤边坡及基础的方法及设计、施工中应注意的一些问题。     

浅谈南通临海公路混凝土桥梁结构耐久性设计

阐述了南通临海公路混凝土桥梁结构耐久性设计需要从结构用材料的自身特性、混凝土结构的设计和施工质量、桥梁结构所处的环境、构件的使用条件和防护措施等方面考虑。     

沿海地区公路危桥成因分析与对策

随着国民经济的发展,我国部分在20世纪50～80年代修建的桥梁面临诸多问题。近年来,广西沿海地区的部分桥梁变成危桥,给公路交通带来了很大的安全隐患。文章以广西沿海公路桥梁为例,分析了沿海地区危桥发展的过程与成因,提出了相应的对策,为解决公路危桥问题提出了参考性的意见。     

石灰改良滨海盐渍土的工程特性研究

研究了传统无机结合料石灰固化滨海盐渍土物理力学性质的变化规律及影响因素,为相关滨海地区公路工程建设中利用盐渍土作为建筑材料,提供一定的科学依据。     

Cross-shelf circulation and phytoplankton distribution at the summertime New England shelfbreak front

We investigate aspects of the secondary (cross-shelf) circulation at the Middle Atlantic Bight shelfbreak front using high-resolution data collected on the New England Shelf in August 2002. The alongshore shelfbreak jet coincides with the front at the seaward edge of the cold pool (remnant winter shelf water) and there is a suggestion of a cross-stream convergence centered at the jet core. Despite indications of convergence we found no evidence of a surface subduction on the seaward side of the front. At depth 70 m near the shelfbreak there was a patch of chlorophyll, located within a local temperature–salinity maximum which, though significantly below the euphotic zone, appeared to be photo-acclimated and viable. The chlorophyll feature could be the result of a local subduction by a larger scale eddy circulation seaward of the front.Dye tracer experiments directly observed the convergence at the foot of the shelfbreak front and subsequent upwelling of bottom boundary layer water along the shoreward side of the shelfbreak front. But, we found no evidence that this upwelling influenced productivity at the front. Further, since there was no cross-shelf maximum in subsurface chlorophyll at the front, we conclude that this productivity is in general, sustained by a broadly distributed local vertical nutrient flux from an underlying nutrient reservoir.