南汇近岸水域近底层泥沙运动和边滩沉积

根据长江口南汇近岸水域17个站的水文泥沙同步观测资料,阐述了该水域近底层泥沙的流速、悬沙浓度的分布和变化。经无量纲潮流动力值的计算表明,研究区存在一个包络南汇边滩先向东南继而向南延伸的舌状高能量区,与高悬沙浓度分布区相一致。通过对悬沙运动和涨、落潮周期流向的分析,揭示了长江口向杭州湾底层泥沙输移的规律,其底层泥沙输移主要集中在低潮位时段,输移时间约占潮周期的36%,其中以南汇边滩向杭州湾输移的时间为最长,大、小潮都在5h以上,与其相关联,在芦潮港水域下层存在着一股东西向的高悬沙浓度的水体。据盐度、潮流、悬沙浓度等要素,并结合絮凝沉降分析得出,南汇边滩的沉积强度是潮滩>潮下带>深水区;边滩舌尖前缘水域的泥沙沉积时间与水体出现向东偏南或向西流的时间一致,这可视为近年来南汇水下沙嘴向东偏南伸展的原因之一。     

浙江沿岸和长江口区潮流能源及其开发利用

本文根据《全国海洋能资源区划技术规定》的要求,首先对浙江及长江口区沿岸潮流流速在2.5kn以上的港湾、水道进行了潮流能资源调查研究,并在查明该区潮流能资源蕴藏量及分布的基础上,为潮流能的开发利用提供了科学依据。此外,本文对潮流能资源开发利用的现状及今后开发研究问题提出了一些看法和建议。     

小清河入海污染物扩散特征及其对近岸工程建设的响应

河流入海污染物是近海污染物的主要来源之一。小清河是莱州湾西南部主要入海河流和污染物来源,近年来小清河口两侧近岸工程建设规模不断扩大,其对小清河入海污染物扩散的影响如何有待深入研究。采用MIKE21数值模型模拟了近岸工程建设对潮流场的影响及小清河入海污染物（无机氮、活性磷酸盐）的扩散特征,探讨了入海污染物扩散对近岸工程建设的响应。研究结果表明：小清河口两侧近岸工程的建设,导致小清河河口附近海域流速有所减小,减小值介于2～21 cm/s。河口两侧的堤坝、防波堤等工程阻挡了污染物向东南、西北方向扩散,使小清河入海污染物扩散范围有所减小,不利于污染物扩散,导致河口附近海域污染物浓度有所增加,从而加剧了小清河河口附近海域的水质污染。因此,近岸工程建设会造成工程附近海域的潮流减弱,削弱近海海域的污染物扩散能力。     

近岸波浪传播折射变形的数学模型综述

对研究近岸波浪折射变形的各种数学模型（基本方程和数值方法）进行了较为系统的归纳总结和评述,内容包括线性规则波折射数学模型,非线性规则波折射数学模型,波群折射数学模型,不规则波折射数学模型。     

Enhanced Acoustic Backscatter Due to High Abundance of Sand Dollars,Dendraster excentricus

Abstract

Detailed acoustic surveys of benthic sediments were conducted in July 1995 and September 1998 in the vicinity of Humboldt Bay, California. During these surveys, a band of enhanced acoustic backscatter was observed offshore from the bay entrance, approximately parallel to the isobaths, in water depths ranging from 16–24 m. In order to assess the cause of the increase in backscatter levels, a more comprehensive study was conducted in August and September 1999 using 100 kHz side-scan sonar, bottom grab sampling and underwater video recording. New observations indicated that a dense population of sand dollars (Dendraster excentricus) coincided with the enhanced backscatter band. Compared to the two previous acoustic studies, the central section of the band expanded westward by 180 m and the southern section of the band shifted eastward by 160 m, possibly resulting from a change in the biological or physical factors which influence the location and breadth of sand dollars.

The relationship between high sand dollar abundance and enhanced acoustic backscatter was further verified in the near shore region off Samoa Beach California, where a dense, banded population of sand dollars was previously observed. Video footage confirmed the presence of a band of sand dollars, also nominally parallel to the isobaths, in water depths of 8–15 m. A band of enhanced backscatter coincided with the dense sand dollar population. The identification of dense aggregations of sand dollars through enhanced acoustic backscatter could lead to the use of acoustic techniques to study sand dollar distributions and abundance.     

鳌山湾水域水文设计参数分析

根据青岛大港验潮站的长期实测资料和鳌山湾连续一年的历时潮住资料,利用PearsonⅢ型曲线法和同步相关方法分析获得了鳌山湾极值水位及鳌山湾水域的设计水位。在此基础上,计算得到了深水和近岸波要素。所得水文设计参数为鳌山湾的后续开发提供了科学依据。     

Depositional model for lacustrine nearshore subaqueous fans in a rift basin: The Eocene Shahejie Formation,Dongying Sag,Bohai Bay Basin,China

The origin of the fourth member of the Eocene Shahejie Formation in the northern steep slopes of the Minfeng Sub‐sag, Dongying Sag, China, was investigated by integrating core studies and flume tank depositional simulations. A non‐channelized depositional model is proposed in this paper for nearshore subaqueous fans in steep fault‐controlled slopes of lacustrine rift basins. The deposits of nearshore subaqueous fans along the base of steep border‐fault slopes of rift basins are typically composed of deep‐water coarse‐grained sediment gravity‐flow deposits directly sourced from adjacent footwalls. Sedimentation processes of nearshore subaqueous fans respond to tectonic activities of boundary faults and to seasonal rainfall. During tectonically active stages, subaqueous debris flows triggered by episodic movements of border‐faults dominate the sedimentation. During tectonically quiescent stages, hyperpycnal flows generated by seasonal rainfall‐generated floods, normal discharges of mountain‐derived rivers and deep‐lacustrine suspension sedimentation are commonly present. The results of a series of flume tank depositional simulations show that the sediments deposited by subaqueous debris flows are wedge‐shaped and non‐channelized, whereas the sediments deposited by hyperpycnal flows generated by sporadic floods from seasonal rainfall are characterized by non‐channelized, coarse‐grained lobate depositional bodies which switch laterally because of compensation sedimentation of hyperpycanal flows. The hyperpycnal‐flow‐deposited non‐channelized lobate depositional bodies can be divided into a main body and lateral edges. The main body can be further subdivided into a proximal part, middle part and frontal part. Normal mountain‐derived river‐discharge‐deposited sediments are characterized by thin‐bedded, fine‐grained sandstones and siltstones with a limited distribution range. Normal mountain‐derived river‐discharge‐deposited sediments and deep‐lacustrine mudstones are commonly eroded in the area close to boundary faults. A nearshore subaqueous fan can be divided into three segments: inner fan, middle fan and outer fan. The inner fan is composed of debrites and the proximal part of the main body. The middle fan consists of the middle part of the main body and lateral edges, normal mountain‐derived river‐discharge‐deposited fine‐grained sediments and deep‐lacustrine mudstones. The outer fan comprises the frontal part of the main body, lateral edges, and deep‐lacustrine mudstones. Based on the non‐channelized depositional model for nearshore subaqueous fans, criteria for stratigraphic subdivision and correlation are discussed and applied.     

Observations on sandbar behaviour along a man‐made curved coast

Sandbars, submerged ridges of sand parallel to the shoreline, affect surfzone circulation, beach topography and beach width. Under time‐varying wave forcing, sandbars may migrate onshore and offshore, referred to as two‐dimensional (2D) behaviour, and vary in planshape from alongshore uniform ridges to alongshore non‐uniform ridges through the growth and decay of three‐dimensional (3D) patterns, referred to as 3D behaviour. Although 2D and 3D sandbar behaviour is reasonably well understood along straight coasts, this is not the case for curved coasts, where the curvature can invoke spatial variability in wave forcing. Here, we analyse sandbar behaviour along the ～3000 m man‐made curved coastline of the Sand Engine, Netherlands, and determine the wave conditions governing this behaviour. 2D and 3D behaviour was quantified within a box north and west of the Sand Engine's tip, respectively, using a 2.4‐year dataset of daily low‐tide video images and a sparser bathymetric dataset. The northern and western sides behaved similarly in terms of 2D behaviour, with seasonal onshore and offshore migration, resulting in a stable position on inter‐annual timescales. However, both sandbar geometry and 3D behaviour differed substantially between both sides. The geometric differences (bar shape, bar crest depth and wavelength of 3D patterns) are consistent with computed alongshore differences in breaker height due to refraction. The differences in the timing in growth, decay and morphological coupling of 3D patterns in the sandbar and shoreline are likely related to differences in the local wave angle, imposed by the curved coast. Similar dependency of bar behaviour on local wave height and angle may be expected elsewhere along curved coasts, e.g. shoreline sandwaves, cuspate forelands or embayed beaches. Copyright © 2017 John Wiley & Sons, Ltd.     

“近岸水下扇”的命名、特征及其储集性

本文对国内"近岸水下扇"的命名及分类进行了总结分析,简述了"近岸水下扇"的沉积模式以及形成条件、各亚相和微相的划分及其沉积特征,提出了影响"近岸水下扇"储集性的因素,评价了"近岸水下扇"各微相砂体的储集性能,指出了富集油气的沉积微相类型以及所形成的油藏类型。     

长江口南汇边滩的演变及其沉积动力机制

南汇边滩是长江口、杭州湾以及外海三者交互作用的特殊地带。根据不同时期海图对比分析发现，南汇边滩北冲南淤，逐渐向东南方向伸展，平均速率为30m/a。通过初步的机制探讨认为，南汇边滩有径流输沙和涨潮回输泥沙的双重补给，加上适宜盐度的絮凝，沉积速率较大，在滩面淤高的同时向水平方向扩展，但北侧受南槽落潮水流南偏的作用而不断冲刷，东侧突出的沙嘴受外海风浪的强烈作用难以东扩，南侧受杭州湾口近东西向的涨落潮流作用，在这些动力泥沙的综合作用下，导致南汇边滩向东南方向伸展。