崇明岛东滩潮沟体系及其沉积动力学

崇明岛东滩潮沟系在盐沼带内特别发育,其形成与潮滩围垦工程和盐沼带的宽度密切相关。泥滩上潮沟的发育和演化与盐沼带潮盆大小、潮时(大小潮)和降雨量等相关,潮沟体系规模小,涨潮流不受其控制,退潮时潮沟成为主要泄水通道,未沉降的细悬浮颗粒和浮泥层在重力作用下向潮沟汇集,使潮沟内沉积物比滩面细。崇明岛东滩潮沟体系形成、演化及沉积物分布,完全不同于目前研究非常详细的欧美河口湾/港湾型潮道-潮沟体系,后者潮道以涨潮流占优势,沉积物明显比滩面粗。崇明岛东滩潮沟体系是发育在快速淤长的三角洲类型海岸上,通过与其他类型的对比研究,可以更全面地认识潮道-潮沟体系对泥滩和盐沼发育、演化所起的作用。     

潮滩前缘盐沼植被簇团与潮沟系统演变相互作用研究

潮滩前缘盐沼植被簇团可以通过改变水动力及泥沙运动等过程影响潮沟系统的地形地貌,而潮沟系统的地形特征也会影响盐沼簇团的生长、扩张与侵蚀,但对盐沼簇团与潮沟系统地貌演变的相互作用机制尚缺乏认识。针对这一问题,本文构建了考虑盐沼植被动态演变的潮滩生物动力地貌耦合模型,模拟了盐沼植被簇团生长扩张与潮沟系统地貌演变过程,分析了不同初始数量的盐沼植被簇团与潮沟系统的空间格局及形态参数间的双向反馈。结果表明,潮沟先迅速向海陆两侧延伸,后发育出大量分汊;盐沼簇团向周边扩张后未被潮沟切割区域逐渐连成片。少量盐沼簇团能够增加潮沟密度,促进边缘冲刷式潮沟系统的发育。潮沟的走向受盐沼簇团分布位置及数量的影响,多个盐沼植被簇团间的水流集中比单个簇团的边缘水流冲刷更易形成潮沟。在盐沼植被簇团与潮沟系统共同发育初期,潮沟系统发育受盐沼植被簇团的促进作用较大,后期潮沟内比簇团边缘更易形成水流汇聚,盐沼簇团的影响逐渐由促进作用转为稳定作用。此外,潮沟的存在限制了盐沼植被的横向扩散,切割了盐沼植被簇团,影响盐沼植被的空间分布格局。本研究揭示了盐沼植被簇团与潮沟系统地貌耦合演化机制,可为盐沼潮滩生态系统保护修复提供科学依据...     

海州湾岸滩演变过程和泥沙流动向

海岸是海与陆这一对矛盾的统一体.在滨海地带呈现出来的海岸地貌,是地质构造和海平面变化、波浪潮流等海水动力以及河流诸因素相互作用的产物,这些因素的运动和变化,促使了岸滩的演变.海州湾是濒临黄海的一个开敞海湾,海州湾海岸是基沿--砂质海岸与淤泥质海岸的交汇地带.     

黄河口海岸冲淤演变的影响因素

采用实测资料分析,对黄河口口门附近海岸冲淤演变的影响因素进行了研究,结果表明:黄河口口门附近海岸为淤泥质海岸,是在河流动力与海洋动力的共同作用下形成的;影响黄河口海岸带冲淤演变的主要因素是黄河入海水沙量和海洋动力;此外,海平面相对升降、地形地貌特征、地质特征、植被情况、人类活动等因素也对海岸冲淤演变有着明显的影响.黄河...     

淤泥质、粉沙质及沙质海岸航道回淤统一计算方法

根据20世纪80年代初提出的淤泥质海岸航道回淤计算方法的基础上,开展了拓展研究,使之统一适用于淤泥质海岸、粉沙质海岸及沙质海岸。主要研究内容有,在波浪和潮流综合作用下挟沙力含沙量研究中引入了特定的泥沙因子F1/F,从而挟沙力含沙量公式不仅适用于淤泥质泥沙,也适用于非淤泥质泥沙;在动力因素方面,除了一般寻常潮和波浪动力外,进一步考虑了风暴潮和破波的巨大掀沙能力造成航道骤淤的可能性。并结合连云港30万吨级主航道扩建及徐圩港区10万吨级航道的回淤问题(包括骤淤可能性问题),京唐港外航道和黄骅港外航道的骤淤问题,进行预测计算及校验计算,结果都是良好的。此外,对杭州湾强潮和涌潮情况下的挟沙力含沙量也进行了校验计算,结果也非常满意。     

浙东淤泥质海岸的泥沙来源和塑造机理

本文以浙东海岸地区水文、泥沙多次调查和各种文献资料为依据，通过对陆域、海域和空域泥沙的平衡计算，揭示了落淤浙东海岸地区的泥沙主要来自长江，它约占总来沙量的９１％，海域和当地河流来沙属同一量级，合占９％，空域来沙不足１ｔ。随之，也进一步论证了长江年输沙量约３０％南下浙江近海，这一观点是可信的。通过潮汐、波浪造滩过程分析，阐明了具有驻波性质的潮流作用于滩面时，造成涨潮流的减速时段长于加速时段，从而使浙东港湾淤泥质海岸在泥沙来源少的条件下仍能缓慢淤涨；开敞性海岸同受潮汐和波浪作用，波浪能在坡缓的淤泥质滩涂造成数公里宽的破碎带，使泥沙不断地来回搬运，海岸呈不平衡态，但因波浪作用时间比潮汐短，泥沙来源丰沛，故多呈淤涨势态。     

潮沟研究现状及进展

潮汉是粉砂淤泥质海岸重要的地貌单元，本文阐述了潮沟的类型划分，地形地貌形态，沉积特征，发展演化诸方面的研究现状及进展。     

欧洲大西洋及北海南部海岸全新世盐沼沉积物自压实作用

全新世时期的海岸层序产生了沼泽和由一系列淤泥和泥炭控制的泥滩,一般仅在横向狭窄体(如潮沟充填物,海岸砂坝)中含有砂和砾石。在全新世时间尺度上,最新的沉积是不易被压缩的,但是淤泥(特别是含有合适比例植被成分的),当然还有泥炭,它们的自压实程度则可能被忽视。自压实盐沼地貌形态动力学、海平面研究、全新世地层和考古学、以及海岸管理方面都很有意义。     

鲁北沿岸贝壳堤的地质学意义

本文通过对鲁北沿岸现代贝壳堤岛的分析认为:贝壳堤发育在冲淤变化不大的粉砂淤泥质岸段,暴风浪是其形成的主要动力;完整的贝壳堤体系应包括海岸贝类生长带(潮滩下部和潮下带)—潮滩侵蚀带—贝壳堤—堤后泻湖;贝壳堤贝壳~(14)C测年资料应当慎用,也不宜把古贝壳堤看成全新世海平面变化的确切标志。     

浙江省海岸侵蚀及防治概述

浙江海岸侵蚀现象普遍存在。基岩海岸海蚀地貌发育,因其组成物质抗冲蚀能力强,岸线后退不明显;砂砾质海岸普遍发生侵蚀,尤其是无计划的人工挖沙,造成沙滩减小或消失;淤泥质海岸大多处于缓慢的淤涨状态,但由于自然条件的改变和人为作用的影响,某些岸段发生侵蚀,特别是受到台风暴潮的影响,岸线在短时间内出现大规模后退和滩面下蚀。侵蚀岸段主要见于杭州湾北岸澉浦至金丝娘桥岸段,杭州湾南岸临山至西三岸段及瓯江口北岸盘石至黄华岸段。淤泥质海岸后缘为滨海平原,组成物质为粘土质粉砂,抗冲蚀能力弱,为防止和减轻海岸侵蚀,沿岸建造各类海岸工程(海塘、丁坝、导堤等),提高防潮抗浪能力,在朝滩种植大米草,互花米草,消浪促淤明显。另外,在海岸开发活动中,应加强海岸侵蚀监测和综合管理。     

海南陵水新村港潮汐汊道演变及其稳定性分析

根据海南陵水新村港附近海区的卫星遥感图及其潮汐汉道的动力场，分析该潮汐汉道的演变状况及其泥沙动力机制，着重于其落潮三角洲的地貌演变与落潮主水道的动力过程，计算分析了其稳定性。研究结果表明，新村港潮汐汉道的落潮主水道表现出有规律的演变，汉道口门稳定性比较高，但其落潮主水道不太稳定。     

Impacts of stormwater discharges on the nearshore benthic environment of Santa Monica Bay

Although large loads of potentially toxic constituents are discharged from coastal urban watersheds, very little is known about the fates and eventual impacts of these stormwater inputs once they enter the ocean. The goal of this study was to examine the effects of stormwater discharges on the benthic marine environment of Santa Monica Bay. Sediment samples were collected across a gradient of stormwater impact following significantly sized storm events offshore Ballona Creek (a predominantly developed watershed) and Malibu Creek (a predominantly undeveloped watershed). Sediments offshore Malibu Creek had a greater proportion of fine-grained sediments, organic carbon, and naturally occurring metals (i.e., aluminum and iron), whereas sediments offshore Ballona Creek had higher concentrations of anthropogenic metals (i.e., lead) and organic pollutants (i.e., total DDT, total PCB, total PAH). The accumulation of anthropogenic sediment contaminants offshore Ballona Creek was evident up to 2 km downcoast and 4 km upcoast from the creek mouth and sediment concentrations covaried with distance from the discharge. Although changes in sediment texture, organic content, and an increase in sediment contamination were observed, there was little or no alteration to the benthic communities offshore either Ballona or Malibu Creek. Both sites were characterized as having an abundance, species richness, biodiversity and benthic response index similar to shallow water areas distant from creek mouths throughout the Southern California Bight. There was not a preponderance of pollution tolerant, nor a lack or pollution sensitive, species offshore either creek mouth.     

Numerical modeling of hyperpycnal flows in an idealized river mouth

Numerical experiments in an idealized river mouth are conducted using a three-dimensional hydrodynamics model (EFDC model) to examine the impacts of suspended sediment concentration (SSC), settling velocity of sediment and tidal mixing on the formation and maintenance of estuarine hyperpycnal flows. The standard experiment presents an illustrative view of hyperpycnal flows that carry high-concentrated sediment and low-salinity water in the bottom layer (>1.0 m in thickness) along the subaqueous slope. The structure and intra-tidal variation of the simulated hyperpycnal flows are quite similar to those previously observed off the Huanghe (Yellow River) mouth. Results from the three control experiments show that SSC of river effluents is the most important parameter to the formation of hyperpycnal flows. High SSC will increase the bulk density of river effluents and thus offset the density difference between freshwater and seawater. Low SSC of river effluents will produce a surface river plume, as commonly observed in most large estuaries. Both the settling velocity of sediment particles and the tidal mixing play an important role in maintaining the hyperpycnal flows. Increasing settling velocity enhances the deposition of sediment from the hyperpycnal layer and thus accelerates the attenuation of hyperpycnal flows, whereas increasing tidal mixing destroys the stratification of water column and therefore makes the hyperpycnal flows less evident. Our results from numerical experiments are of importance to understand the initiation and maintenance of hyperpycnal flows in estuaries and provide a reference to the rapidly decaying hyperpycnal flows off the Huanghe river mouth due to climatic and anthropogenic forcing over the past several decades.     

天津港水域围垦条件下的水动力变化分析

本研究旨在讨论天津滨海新区的围垦对其附近水域水动力和悬沙输运所造成的影响,并进行定量评估。在天津港南部、北部海域分别选取4个站位进行了全潮水文观测,获取了流速剖面、悬沙浓度剖面数据,并据此计算了底切应力、潮不对称性以及余流。结果表明,底部悬沙浓度与流速、底切应力存在相位一致性,绝大部分站位的沉积物都呈现向岸净输运的趋势,悬沙通量分解显示潮汐捕捉项是该区域悬沙输运的主要贡献项;围垦愈增的2009～2015年,天津港北部潮不对称性增强,向陆的单宽悬沙输运率由20.15 g/(m·s)变至24.92 g/(m·s),而南部海域潮不对称性减弱,向陆的单宽悬沙输运率从37.75 g/(m·s)减小至6.37 g/(m·s)。综上,持续地围垦可能导致天津港附近海域的水动力条件改变,推测北部潮滩淤涨可能加快,而南部淤涨速率减小。     

Hydrodynamics and associated sediment transport over coastal wetlands in Quanzhou Bay,China

Coastal salt marshes represent an important coastal wetland system.In order to understand the differences between boundary layer parameters of vegetated and unvegetated areas,as well as the mechanisms of sediment transport,several electromagnetic current meters (AEM HR,products of Alec Electronics Co.Ltd.) were deployed in coastal wetlands in Quanzhou Bay,China,to measure current velocity.During the low tide phase,the surficial sediment was collected at 10 m intervals.In situ measurements show that the current velocities on the bare flat were much higher than those in the Spartina alterniflora marsh.Current velocity also varied with distance from marsh edge and plant canopy height and diameter.Around 63% of the velocity profiles in the tidal creek can be described by a logarithmic equation.Over the bare flat and Spartina alterniflora marsh,a logarithmic profile almost occurs during the flood tide phase.Sediment analysis shows that mean grain size was 6.7 Φ along the marsh edge,and surface sediments were transported from bare flat to marsh;the tidal creeks may change this sediment transport pattern.The hydrodynamics at early flood tide and late ebb tide phases determined the net transport direction within the study area.     

基于遥感和GIS的福建文渡湾海域潮滩演变研究

强潮海区的潮滩冲淤演变对于潮滩开发利用、海洋环境保护及灾害预防等具有十分重要的意义。本文以福建北部文渡湾海域为研究对象,采用遥感和GIS相结合的方法,对淤泥质潮滩的冲淤演变特征进行研究。研究结果表明:1991年以来文渡湾湾顶潮滩地形呈淤积状态,尤其2005年以后淤积明显;淤积的主要原因可能与围垦造陆使得湾口缩窄,致使湾口流速增大、湾口局部海床冲刷的泥沙向湾顶搬运有关。     

Distribution gradients of ichthyoplankton in an East African mangrove creek

As part of an investigation into the role of East African mangrove creeks as fish spawning and nursery areas, nocturnal ichthyoplankton sampling was carried out at five stations in Tudor Creek, Mombasa, Kenya, from September to November 1985. Throughout the creek, the salinity was close to that of seawater at about 35‰, but from the mouth to the upper creek there were gradients of increasing temperature and turbidity, and decreasing depth and dissolved oxygen concentration. Pelagic eggs and larvae of fish considered to be creek residents and creek non-residents were distinguished. Gradients of decreasing egg and larval abundance (particularly of non-residents), and of decreasing diversity of recognized types, were apparent from the mouth towards the upper creek. Such a distribution suggests that the mangrove system is not an important spawning or development area for the earliest life-history stages of non-resident species. The existence of the gradients also has implications both for sampling at fixed stations in tidal waters, and for investigating the existence of circatidal and semilunar spawning cycles in fish.     

黄河清水沟流路稳定性分析

根据１９８９年５月和８月枯、洪水两个季节黄河拦门沙区及河口海区地质和水文调查资料，结合黄河利津水文站近几年的径流量和输沙量变化，对黄河清水沟流路稳定性及其影响因素进行综合分析研究。结果表明，近年来黄河来沙量渐少是清水沟流路稳定的重要因素之一，随着河口向南转向海动力作用较弱的莱州湾，海水沿河上溯力逐渐减弱，河流泥沙得以更顺利入海，并在口门外沉积；现流路河口海域的水动力作用虽然较弱，但涨，落潮流的分布     

弱动力浅海中的悬沙输运机制:以天津港附近海域为例

根据在天津港附近海域获取的水动力和浊度数据,分析了悬沙输运特征和输运机制,结果表明:天津港附近海域受不规则半日潮控制呈低流态往复流特征,但涨潮流强于落潮流;涨潮期间底部悬沙浓度与垂线平均流速呈显著线性相关,存在显著的再悬浮作用;潮周期内的悬沙输运呈典型的不对称特征,形成向岸的净输运趋势。输运机制分析结果显示:潮泵效应(尤其是潮汐捕捉效应)是天津港附近海域悬沙输运的主要贡献项,其次是拉格朗日平流输运项,前者比后者高一个量级;垂向剪切作用最小。涨落潮期间流速与悬沙浓度的显著不对称是造成潮汐捕捉效应占主导的基本条件。在潮下带这种悬沙输运格局可能和潮间带发生的细颗粒沉积物捕集(堆积)作用有关。