1998年长江巨洪与厄尔尼诺事件

1997～ 1 998年出现了 2 0世纪中最强的一次厄尔尼诺事件。根据长江洪水与厄尔尼诺事件的实测资料 ,指出 1 998年的长江巨洪与这次厄尔尼诺事件具有较密切的关系。同时讨论了厄尔尼诺事件影响长江洪水的物理途径 ,这对长江巨洪的长期及超长期预报具有较重要的指示作用     

长江口拦门沙地区的泥沙运动规律

依据１９８８年７月和１２月水文观测资料，通过流，盐，沙的综合分析，认识到长江口拦门沙地区的泥沙运动有与河口其他地区不同的特点，泥沙输移在水平面上和垂直面上存在着多种循环，潮流和盐水截留大量泥沙积聚的拦门沙地区，河口在盐淡水交锋地带，除了涨，落急时段外，发现在转流时期泥沙也可能产生再悬浮，从而形成一个潮周期中出现３次或４次再悬浮的特殊规律。     

Experimental studies on the slowly varying drift motion of a berthed container ship model

The effects of free-surface waves on the floating structures are of great importance in the offshore industry. Among the six degrees of motions of a surface ship the absence of restoring forces in surge, sway and yaw led to critical situations for moored ships in the recent times. The order of forces in horizontal plane and their exciting frequencies are matters of interest. The resonance with the presence of moored chains led to many accidents in the recent past. The lines in dry conditions may not give good damping and in wet condition they may trigger the system to chaotic motions and jumps. Two different loading conditions of a container ship model are tested with waves in laboratory conditions in two different drafts. The mooring lines are chosen as per scale law and the energy under the response spectrum is determined from the plots. The results give new insights into the movement of a berthed ships subjected to waves. Response of the moored ship to different loading conditions in different water depths are discussed in this paper. The paper gives the order of energy due to first-order and slowly varying movement of a berthed container model in a towing tank.     

Effect of dispersion on impulsive waves

The generation and propagation of surface waves resulting from suddenly created disturbances over water surfaces is investigated. The initial boundary conditions defining the disturbance are given either by a velocity of the free surface, an initial elevation of the free surface or a pressure impulsively applied on the free surface. It is shown that the corresponding three forms of solutions are related by a simple time derivative. Linear solutions are obtained in the cases where the wave motion is assumed to be nondispersive, mildly dispersive and fully dispersive, as well as in the case where the motion is given by the method of stationary phase. Criteria are established to indicate the limit of validity of each method.     

Nutrients and zooplankton composition and dynamics in relation to the hydrological pattern in a confined Mediterranean salt marsh (NE Iberian Peninsula)

The role of the hydrological regime in the nutrients and zooplankton composition and dynamics has been analysed in five lagoons of La Pletera salt marshes (NE Iberian Peninsula) during a complete hydrological cycle (2002–2003). Two of the lagoons have their origin in the old river mouths while the other three were recently created in the framework of a Life Restoration project. This fact has also allowed us to study the effect of the lagoon age on nutrient and zooplankton composition and dynamics. The salt marsh hydrology is determined by a prolonged period of confinement without water inputs, irregularly interrupted by sudden water inputs due to flooding events (sea storms or intense rainfalls). While the dynamics of oxidized nitrogen compounds in the lagoons depends on the water inputs variability within each hydrological cycle, the internal load of phosphorus, total nitrogen and organic matter is related more to the cumulative mechanisms during the confinement periods. Accumulation processes may be easily related to lagoon age, since old lagoons have higher content of nutrients and organic matter, suggesting that these lagoons progressively accumulate nutrients during the successive confinement events. This is the usual case for most Mediterranean salt marshes without an artificially manipulated water regime. The zooplankton community in La Pletera integrates the effects of both the hydrological regime and the lagoon age since the former determines the temporal pattern of the main zooplankton species and the latter explains differences in composition and structure between old and new lagoons.     

Comparison of two three-dimensional hydrodynamic modeling systems for coastal tidal motion

A comparison of two three-dimensional numerical modeling systems for tidal elevations and velocities in the coastal waters is presented. The two modeling systems are: (1) the Princeton Ocean Model (POM) and (2) the MIKE 3 flow model. The model performance results for Singapore's coastal waters show that the predicted tidal elevations from the two hydrodynamic modeling systems are almost identical and are in very good agreement with field measurement data. The simulated tidal current velocities match well with field measurement data at the selected stations, but it seems that the POM provides the slightly better simulation, compared to the MIKE 3 flow model. The depth profiles of the velocities obtained from the two modeling systems may be greatly different at some time, due to the vertical diffusion coefficient calculated from different turbulent sub-models in the two modeling systems. The POM generally predicts larger peak tidal velocities. The maximum speed differences for the model results from the two modeling systems occur in the top and differ from time to time and from location to location, reaching up to 20%.     

Late Holocene estuarine–inner shelf interactions; is there evidence of an estuarine retreat path for Tampa Bay, Florida?

The purpose of this study was to determine if and how a large, modern estuarine system, situated in the middle of an ancient carbonate platform, has affected its adjacent inner shelf both in the past during the last, post-glacial sea-level rise and during the present. An additional purpose was to determine if and how this inner shelf seaward of a major estuary differed from the inner shelves located just to the north and south but seaward of barrier-island shorelines. Through side-scan sonar mosaicking, bathymetric studies, and ground-truthing using surface grab samples as well as diver observations, two large submarine sand plains were mapped – one being the modern ebb-tidal delta and the other interpreted to be a relict ebb-tidal delta formed earlier in the Holocene. The most seaward portion of the inner shelf studied consists of a field of lobate, bathymetrically elevated, fine-sand accumulations, which were interpreted to be sediment-starved 3D dunes surrounded by small 2D dunes composed of coarse molluscan shell gravel. Additionally, exposed limestone hardbottoms supporting living benthic communities were found as well. This modern shelf sedimentary environment is situated on a large, buried shelf valley, which extends eastward beneath the modern Tampa Bay estuary. These observations plus the absence of an incised shelf valley having surficial bathymetric expression, and the absence of sand bodies normally associated with back-tracking estuarine systems indicate that there was no cross-shelf estuarine retreat path formed during the last rise in sea level. Instead, the modern Tampa Bay formed within a mid-platform, low-relief depression, which was flooded by rising marine waters late in the Holocene. With continued sea-level rise in the late Holocene, this early embayment was translated eastward or landward to its present position, whereby a larger ebb-tidal delta prograded out onto the inner shelf. Extensive linear sand ridges, common to the inner shelves to the north and south, did not form in this shelf province because it was a low-energy, open embayment lacking the wave climate and nearshore zone necessary to create such sand bodies. The distribution of bedforms on the inner shelf and the absence of seaward-oriented 2D dunes on the modern ebb-tidal delta indicate that the modern estuarine system has had little effect on its adjacent inner shelf.     

An Experi mental Study on Wave-Induced Dynamic Stresses in Seabed

1 .IntroductionEvery year ,Taiwanis subjectedtotwo or three typhoonintrusions in average which always causedisasters . Most of the disasters which occur around the coastal zone are due to seabed instability andcoastal structure destruction caused bytyphoo…     

大型海藻龙须菜与锥状斯氏藻间的营养竞争研究

利用生物和化学方法研究了大型海藻龙须菜（Gracilaria lemaneiformis）与赤潮生物锥状斯氏藻（Scrippsiella trochoidea （Stein） Loeblich Ⅲ）共培养时二者的生长情况,以及二者之间营养盐NO-3、PO3-4竞争的情况.结果显示,两者共培养时,由于龙须菜的影响,锥状斯氏藻的生长周期以及所能达到的最大细胞密度与对照组相比都有所下降,且受抑制程度随龙须菜起始密度的增大而增强;而锥状斯氏藻对于龙须菜的生长不构成明显的影响.当龙须菜起始密度较低时（0.2、0.1gFW/L）,共培养组微藻细胞密度的下降是因为水体中NO-3的耗尽;当龙须菜起始密度较高时（0.5gFW/L）,共培养组微藻细胞密度的下降可能是因为龙须菜与微藻之间的“互荫效应”,或者龙须菜能够分泌出足够浓度的克生物质所致.龙须菜可作为有效吸收营养盐的大型海藻,用以降低近海水域富营养化程度及有害赤潮发生的几率.     

厄尔尼诺的发生与行星运动

厄尔尼诺(El Ni(?)o)现象是海-气耦合系统异常变化的表现,其起因可能不是唯一的,行星运动对地球运动的影响可能会导致El Ni(?)o的发生。根据4个半世纪内El Ni(?)o发生的历史资料,分析其发生和行星运动的关系,得出的结论是:木星赤纬的变化和火星大冲与El Ni(?)o。的发生有显著的关系,表明这2颗行星的运动可能影响El Ni(?)o的发生。文中还根据分析结桌和El Ni(?)o混沌机制的观点,探讨了行星运动对海-气系统变化的影响机制。