Tidal effects on estuarine circulation and outflow plume in the Chesapeake Bay

The response of the Chesapeake Bay to river discharge under the influence and absence of tide is simulated with a numerical model. Four numerical experiments are examined: (1) response to river discharge only; (2) response to river discharge plus an ambient coastal current along the shelf outside the bay; (3) response to river discharge and tidal forcing; and (4) response to river discharge, tidal forcing, and ambient coastal current. The general salinity distribution in the four cases is similar to observations inside the bay. Observed features, such as low salinity in the western side of the bay, are consistent in model results. Also, a typical estuarine circulation with seaward current in the upper layer and landward current in the lower layer is obtained in the four cases. The two cases without tide produce stronger subtidal currents than the cases with tide owing to greater frictional effects in the cases with tide. Differences in salinity distributions among the four cases appear mostly outside the bay in terms of the outflow plume structure. The two cases without tide produce an upstream (as in a Kelvin wave sense) or northward branch of the outflow plume, while the cases with tide produce an expected downstream or southward plume. Increased friction in the cases with tide changes the vertical structure of outflow at the entrance to the bay and induces large horizontal variations in the exchange flow. Consequently, the outflow from the bay is more influenced by the bottom than in the cases without tide. Therefore, a tendency for a bottom-advected plume appears in the cases with tide, rather than a surface-advected plume, which develops in the cases without tide. Further analysis shows that the tidal current favors a salt balance between the horizontal and vertical advection of salinity around the plume and hinders the upstream expansion of the plume outside the bay.     

珠江口伶仃洋滩槽变化及演变分析

借助GIS和遥感技术,计算分析了20a来珠江口伶仃洋滩槽演变特点,阐明了其变化原因和后果,并以此提醒人们要从可持续发展的高度规范岸区开发行为,以利于珠江三角洲的长期稳定发展.     

Ground water hydrochemical characteristics:seawater intruded area in eastern and southern coast of Laizhou Bay

Eastern and southern coastal zones of Laizhou Bay are the most representative seawater intruded areas in the world, with two intrusion sources of contemporary seawater and paleobrine. In order to reveal the complicated hydrochemical changing process and the mechanism of fresh groundwater being polluted by saltwater, we conducted long-term observation and hydrochemical analysis at four observing sections of typical salt-fresh water transitional zone. The study indicates that seawater and brine intrusion processes have different hydrochemical features, and that ion exchange and adsorption actions between water and aquifer produce great influence on the intrusion.     

莱州湾地区500年来旱涝灾害指数系列的建立

作者根据《山东省历代自然灾害志》的记载，应用Foxpro提供的软件，建立了莱州湾地区500年来旱涝灾害的汉字库，并通过一系列转换，将其转为数字库；将旱涝灾情的文字记我转换为区域旱涝指数，并与现代降水资料相对接，建立了1470－1990年共521年的历年逐季旱涝灾害指数序列，为分析该地区旱涝灾害发生规律和预测提供了依据。     

莱州湾地区10万年以来沉积环境变化

本文用热释光测年和地球化学标志法研究了莱州湾地区沉积环境的变化。石英的375℃热释光峰作为测年基础。岩芯样品的测定结果、反映了自全新世(1.2万年)至晚更新世(11万年)地层的年代特点。实验中来用了Sr/Ba、Rb、Mn/Fe和CaO作为地球化学标志,所得数据经Sheppard方程和Fisher判别处理。在得到的沉积环境变化曲线和大洋δ~(18)O曲线对比中可以看出,本区在十万年以来出现过三次海陆相地层变化序列,其中在距今11—7万年和深度为43.5—60m处,在距今4.6—2.1万年和深度为23—35m处,以及在距今1.1—0.6万年和深度为8—11m处出现过三次海相地层,分别与沧州、献县和黄骅海侵事件相应,并同时受到全球气候变化的控制。     

台兴油田下第三系阜宁组下亚段储层沉积微相研究

通过钻井、测井资料分析,建立了台兴油田下第三系阜宁组(Ef3)下亚段测井相与沉积微相的关系,研究了台兴油田的沉积微相类型及主要含油气单元———各砂体沉积微相的平面展布特征。研究表明,Ef3下亚段主要砂体沉积微相类型为水下分流河道、河漫滩、河口砂坝以及席状砂沉积微相。     

最近50年来莱州湾东部典型砂岸潮上带土地利用变化研究

以不同时期测量和成像的地形图和高分辨率遥感影像为数据源,综合使用野外调查、遥感(RS)、全球定位系统(GPS)和地理信息系统(GIS)等方法,对最近50多年来莱州湾东部砂岸典型岸段(界河口—刁龙嘴)的土地利用变化进行研究。结果表明,最近50多年来,莱州湾东部海岸土地利用/土地覆被变化显著,土地利用类型转化的总趋势是风沙地、林地、耕地向养殖池及居民地转化。从20世纪90年代初以来,该岸段潮上带风沙地大部分已为养殖池(塘、大棚)等所覆盖,在沿海防护林和海域之间新出现了一条平行于岸线、基本连续展布的水产养殖设施带,其外侧建有高出当地最高潮位的防浪堤。潮上带土地覆被的如此深刻变化,必然深刻地改变风暴潮作用时的水动力边界条件,导致风暴潮作用过程中沿水下岸坡—海滩—潮上带方向的能量分布发生调整,进一步会对海岸地貌及冲淤发生的范围、强度、性质和形式等带来变化。因此,大面积的潮上带土地利用可能是莱州湾东部砂岸,最近30年来海岸地貌冲淤演变的重要影响因素之一,这为今后深入研究并预测该段海岸地貌冲淤变化提供了新的视角。     

深圳大鹏半岛南岸西冲海滩的沉积物来源、平面形态稳定性及横向变化

The coast of the Dapeng Peninsula has been honored as one of "the eight most beautiful coasts in China". The most precious tourism resource for the peninsula is headland bay beaches, among which the beach at Xichong on the southern coast of the peninsula is the longest and the most important one. The information of the stability, sedimentary source and shape change of the beach is very important for maintaining the beach in terms of sustainable development of the peninsula. Heavy minerals in the sand of the beach and the inland stream at Xichong are compared with those of a nearby beach on the same coast to determine the beach sand source; with help of a computer software, MEPBAY, the equilibrium planforms of the beaches on the peninsula are compared with those of an island without rivers to evaluate the stream’s effects on the beach stability; cross shore profiles along the Xichong beach are also surveyed in different seasons of a year to assess the annual shore normal beach changes affected by the stream input, and the relation between the equilibrium planform state and cross shore changes of the beach. It is shown that(1) stream is the main sedimentary source of the beach and the weathering materials of the rocky headlands on both sides of the bay transported by waves are the second source for the beach but it is limited, sand from an inner shelf is not the sedimentary source for the beach at present and was not even during the Holocene transgression;(2) the Xichong beach cannot reach static equilibrium around the entire bay shoreline, the segment of the shoreline where a stream outlet is located is in dynamic equilibrium, and the unstable section occurs in the wave shadow region in the lee of an offshore island;(3) no matter whether the section of the beach shoreline at Xichong is in an equilibrium state or not, it is eroded in the typhoon season and recovered after the season, the maximum change in erosion and accretion occurs in the unstable segment;(4) the Xichong beach can only have small sand body since it is supplied with sand mainly form inland streams, resulting in a possible danger in which sand loss induced by human activities or huge storms cannot be replenished naturally.     

基于生态系统服务的海洋健康评估与调控:以莱州湾为例

近岸海域的生态系统管理,要求对海洋健康进行综合的评估以及对人工调控进行科学的指导,进而促进可持续发展。本文构建了定量化方法,用于评估当前的和近期的基于生态系统服务的海洋健康。以莱州湾为例的研究结果表明,当前的海洋健康指数分值为0.7856(总分为1.0);通过对负面压力进行不同强度的人工调控,得到近期海洋健康预计的变化范围为0.5551到0.8041。具体地说,本文评估得到当前的海洋健康主要表现为文化服务和供给服务基本优秀,而支持服务和调节服务不够良好。若不对持续增长的压力采取有效的调控措施,该近岸海域生态系统会在近期丧失部分支持服务和调节服务;若负面压力被完全控制,该近岸海域生态系统服务的分类等级会得到小幅提升。另外,应进一步加强对生态系统服务尤其是文化服务和调节服务的宣传教育。本文的分析过程和量化结果,为进一步指导人工调控提供了灵活的工具,有助于海岸带区域的生态系统管理。     

三门湾春季温排水增温效应数值模拟研究

采用ECOMSED模式和2012年5月份现场温盐、潮流以及气象观测资料,对三门湾核电站冷却水排放所致海水增温效应进行了数值模拟研究。结果表明,在近期工程建成后,三门湾海水增温范围主要出现在排水口附近,表层增温幅度最大,底层增温幅度最小,在月度时间内,表底层增温范围有大、小极值变化。在全部工程完成后,温排水量大幅提高,三门湾表层海水增温1℃的范围将稳定影响较大面积,4℃增温范围较小。在月度时间内,表底层增温范围大、小极值变化幅度也将增大。