河口闸下淤积和清淤措施研究综述

淤泥质河口建闸后需要解决泥沙淤积的问题,它制约着河口的综合利用。本文就我国淤泥质河口挡潮闸引起的闸下淤积和清淤措施研究成果进行了综述。首先归纳了我国主要建闸河口闸下淤积类型.多数学者根据潮波变形理论和不平衡输沙理论对闸下淤积的力学机理和控制因素进行分析,解释和预测河口闸下淤积的基本特征和发展趋势。提出不同类型的建闸河口防淤减淤措施。最后指出目前研究中的不足和以后应进一步加强研究的问题。     

挡潮闸下港道清淤机具的改进及应用

我国许多挡潮闸，地睛淤泥质海岸，闸下港道淤积十分严重。为了清除闸下港道淤积，提高挡潮闸的排涝能力，对耙具作了改进，经历了单面齿耙、双面齿耙、掺气耙和改进型掺气耙四个发展阶段，本文介绍清淤耙的发展过程，并对各种耙具进行了对比。拖耙清淤机具具有效率高、费用低的特点，每立方米的清淤成本仅为常规挖泥船的三分之一左右。     

甬江建闸前后冲淤特性的初步数值模拟

本文建立了纵向一维和垂向二维两种泥沙运动数值模式,以模拟甬江建闸前后泥沙冲淤规律。模式成功地进行了三汊点(即宁波三江口)水力、盐度、泥沙要素的计算。应用一维模式计算,对甬江建闸前后泥沙冲淤特性及动力机理作了探讨分析;垂向二维的计算结果,说明了泥沙的垂向效应及其对冲淤的影响程度。模式结果也反映建闸后涨潮流阶段泥沙过饱和淤积状态加强,落潮流阶段泥沙次饱和冲刷状态减弱,此是造成甬江大量淤积的主要原因。     

潮汐河口支流建闸闸下淤积研究

潮汐河口建闸的关键问题是闸下淤积。在潮汐河口支流口门上建闸,其闸下淤积面貌主要取决于干流主槽的位置,这与在潮汐河口干流上建闸的闸下淤积问题有着本质上的差异。以钱塘江河口支流曹娥江口门建闸为例,应用河床演变分析、动床实体模型和现场冲淤试验预测了曹娥江大闸闸下淤积面貌和淤积速率,为曹娥江大闸的建设提供了科学依据。     

泥质河口闸下冲淤特性及冲淤量的分析预报

通过泥质河口建闸工程闸下淤积特性的分析研究表明,闸下河段淤积的条件是涨潮流带入河段的泥沙数量大于落潮流从河段内带走的泥沙数量。其水动力原因是径流量减小和潮波变形。在此基础上提出了建闸工程和建闸与双导堤相结合闸下淤积和冲刷的分析预报方法,这些冲淤分析预报方法得到了相关工程的实测资料及浑水动床物模试验结果的验证。     

不同类型建闸河口闸下淤积模拟计算

针对闸下淤积问题建立三维水动力和泥沙数学模型,在挟沙能力公式中考虑浮泥的影响,采用枚举法和最小二乘法相结合率定公式中的参数,较好地反映了建闸河口概化物理模型闸下三维水流和含沙量分布.采用该数学模型研究了短引河河道型、短引河滩槽型和长引河河道型三种类型建闸河口闸下淤积特性.结果表明,在计算条件相同的情况下,建闸河口闸下淤积速率和淤积总量与闸下河道长度、滩槽宽度有关;短引河河道型闸下初始淤积速率最大,长引河河道型闸下初始淤积速率最小;长引河河道型闸下累积淤积厚度最大,短引河滩槽型闸下累积淤积厚度最小;长引河河道型闸下河道淤积总量最大,短引河滩槽型闸下河道淤积总量最小;闸下河道两侧滩地的归槽水对闸下河道减淤作用明显.     

三沙湾潮滩涨落潮和大小潮冲淤特征及其动力机制

潮滩不同尺度的变化规律一直是地表过程研究的核心之一。利用声学多普勒流速仪（ADV）、温盐深（CTD）、光学后向散射浊度计（OBS）对三沙湾潮滩涨落潮和大小潮冲淤及动力变化进行了高精度的观测。结果发现,潮周期内,潮滩冲淤呈现涨潮初期冲刷-落潮末期淤积-中间时段稳定的特征,涨潮初期水深<1 m的30 min内平均冲刷4.05 mm,落潮末期水深<1 m的30 min内平均淤积3.72 mm,中间时段动态稳定;大小潮周期内,呈现中潮到小潮平均淤积3.4 mm,小潮到大潮平均冲刷8.2 mm的特征。通过流速、紊动能、水深、悬沙浓度等因子与冲淤的相关性分析发现,潮周期内,流速和紊动能的增减决定涨潮初期冲刷和落潮末期淤积的变化;大小潮周期内,涨潮冲刷大于落潮淤积的特性决定了大潮到小潮阶段的冲刷,涨潮冲刷小于落潮淤积决定了小潮到大潮阶段的淤积。涨落潮周期和大小潮潮周期的冲淤机制为潮滩动力地貌和动力沉积学研究提供了一定的参考。     

新沂河海口控制工程闸下河道冲刷试验研究

新沂河海口控制工程深泓闸闸下泓道长约１．３ｋｍ,河床由淤积历时较长的淤泥质粘性土组成。试验中首先取原状土土样,通过水槽试验确定起动流速,据此选择模型沙和进行模型设计。试验表明,下游河道冲刷主要由过闸水流及河口跌水造成,其中,前者形成的冲刷坑为设计的控制条件。根据试验结果认为,对于新沂河海口控制工程这样流量大、河口潮位低的闸下泓道,冲刷是不可避免的,建议放弃海漫防冲的方法,改设板桩截墙。试验中采用的某些观点和方法,对于淤泥质粘土海岸地区河口段闸下冲刷研究具有一定的参考价值。     

江苏淤泥质海岸入海河道闸下淤积研究

通过建立ARIMA模型,分析了江苏淤泥质海岸四条入海河道(射阳河、新洋港、斗龙港和黄沙港)建闸后闸下河道的冲淤演变过程,预测闸下河道淤积量的变化情况。结果表明,射阳河闸下淤积量将会持续增加,到2010年预计量可达2.47×107m3,淤积量为四条河中最大;黄沙港和斗龙港有波动上升的趋势,但无射阳河明显,淤积量有小幅度增加;新洋港变化不大,已达到冲淤平衡的状态。     

柘林湾多口门潮汐汊道动力地貌的演变

潮汐汊道是连接内湾和外海、维持港口通航和水体交换的枢纽,其演变特征是整个澙湖、海湾地貌体系研究的基础。选取典型多汊型潮汐汊道系统——柘林湾为研究对象,以实测资料和历年海图、地形图为基础,结合SELFE(semi-implicit Eulerian-Lagrangian finite-element)模型,研究多汊型潮汐汊道水动力结构、泥沙运动及自然和人类活动影响下的演变特征。结果显示,20世纪70年代澄饶大联围之前,共享柘林湾125km2纳潮水域的5个汊道同时维持稳定;围垦工程后,西侧2个汇潮口门封闭,纳潮面积减少50%,导致湾内动力减弱,韩江来沙中断,湾外浅滩冲刷,泥沙向湾内输送,30多年来三百门水道显著淤积,小金门稳定,大金门冲淤调整,小门水道淤积不稳。围垦工程后小金门水道的纳潮面积变化甚少,水动力及输沙仍为落潮占优,汊道环流发育,汊道断面冲淤微调,维持稳定;大金门汊道所控制的纳潮面积减小1/3,口门涨、落潮流速不对称性减弱,汊道冲淤调整;小门水道纳潮面积剧减一半以上,汊道延长弯曲,大金门与小门水道的环流结构加剧了该汊道的淤积和不稳定。     

Silting in the Lower Courses of Tidal Sluices in China

Serious sediment deposition often occurs after the construction of tidal sluices in snrall or medium-sized tidal muddy estuaries, so desilting or dredging is needed to meet the demands of flood diseharge, saltwater retaining, and navigation in those areas. In this paper, the problem of sediment deposition induced by construction of tidal sluices is analyzed.Different problems of silting near tidal sluices for different types of estuaries are summed up. at the same time, corresponding methods are given to solve these probleras, and a few successful examples are also given. The idea of comprehensive regulation and utilization of estuaries is put forward, and some proposals for solution of sediment deposition in this kind of estuaries are made.     

Effects of different types of nutrient effluent from shrimp ponds on the seedling growth of Kandelia obovata

Extensive shrimp ponds are located next to the landward edges of most of mangrove forests in China. A shrimp pond may influence mangroves by(1) routine effluent between pond and tide, and(2) dredging effluent from pond-dredging at least once a year. Our study consisted of two experiments to study the effects of these two effluents on the seedling growth of Kandelia obovata. One experiment simulated the effects of routine effluents.The other simulated four sedimentation thicknesses(0 cm, 2 cm, 4 cm, 8 cm) over mangrove soils by dredging effluent from pond-dredging, and revealed the cumulative effects of dredging effluents on K. obovata. At each of the three fixed salinities, i.e., 5, 15 and 25, routine effluent did not result in significant differences in each of the measured growth parameters of K. obovata seedlings. However, effects of dredging effluent on seedling growth of K. obovata were related with sedimentation thickness. Most growth parameters showed maximum values at sedimentation thickness 4 cm. The data indicated that K. obovata accelerated its growth under moderate sedimentation thicknesses and it was tolerant and adaptable to shrimp pond-cleaning effluent sediments up to about 8 cm in our experiment.     

不同类型的高位虾池排污对秋茄幼苗生长的影响

中国多数红树林陆地边缘存在着大量的养虾池塘。这些养虾池塘可通过：（1）换塘外排废水,（2）清塘直排污泥影响周围的红树林。本研究共包含两个实验,来探讨这两种类型的排污对秋茄幼苗生长的影响。实验一模拟虾池常规换塘情况,研究换塘废水对秋茄幼苗生长的影响。实验二设置四种虾池清塘污泥沉积厚度（0 cm,2 cm,4 cm,8 cm）,研究虾池清塘污泥的累积效应对秋茄幼苗生长的影响。结果如下：在5,15和25三种盐度下,虾池换塘废水未对秋茄生长指标造成显著影响;而清塘污泥对秋茄生长的影响与其沉积厚度有关,大多数生长参数在污泥沉积厚度为4 cm时呈现最大值。秋茄幼苗在适量的沉积厚度下加速了生长,且本实验秋茄幼苗对虾池清塘污泥的耐受性为沉积厚度8 cm。     

沉积物对珊瑚礁及礁区生物的影响

海水中日益增多的悬浮物和泥沙沉降是导致珊瑚礁严重衰退的原因之一。沉积物覆盖在珊瑚礁生物表面,影响其呼吸作用,而海水浊度的增加会减少光合作用的可利用光。过多的沉积物改变了礁区的物理以及生物过程,从而对珊瑚礁生态系的结构和功能产生不利影响。为了有效评估珊瑚礁的变化趋势,如优势种丰度以及空间分布的变化等,应用标准的监测方法进行长期监测对于掌握这一复杂生态系统的变化是非常关键的。综述了沉积物对珊瑚生长率、生长形态、代谢和繁殖与补充以及礁区生物的影响,并指出未来的研究方向,以期为珊瑚礁的保护提供参考。     

Recovery of the seabed following marine aggregate dredging on the Hastings Shingle Bank off the southeast coast of England

The aim of this study was to investigate the effect of dredging intensity on the physical and biological recovery times of the seabed following marine aggregate dredging. Two areas of seabed, previously subject to, respectively, relatively high and lower levels of dredging intensity, were identified on the Hastings Shingle Bank. Two reference areas were also selected for comparative purposes. All four sites were monitored annually over the period 2001–2004, using a combination of acoustic, video and grab sampling techniques. Since the site was last dredged in 1996, this was intended to provide a sequence of data 5–8 years after cessation of dredging. However, an unexpected resumption of dredging within the high intensity site, during 2002 and 2003, allowed an additional assessment of the immediate effects and aftermath of renewed dredging at the seabed. The early stages of recovery could then be assessed after dredging ceased in 2003. Results from both dredged sites provide a useful insight into the early and latter stages of physical and biological recovery. A comparison of recent and historic dredge track features provided evidence of track erosion. However, tracks were still visible 8 years after the cessation of dredging. Within the high dredging intensity site, recolonisation was relatively rapid after the cessation of dredging in 2003. Rather than indicating a full recovery, we suggest that this initial ‘colonization community’ may enter a transition phase before eventually reaching equilibrium. This hypothesis is supported by results from the low intensity site, where biological recovery was judged to have taken 7 years. Further monitoring is needed in order to test this. An alternative explanation is that the rapid recovery may be explained by the settlement of large numbers of Sabellaria spinulosa. As the resumption of dredging within the high intensity site limited our assessment of longer-term recovery it is not yet possible to assume that a 7-year biological recovery period will be applicable to other, more intensively dredged areas at this or more distant locations.     

海水养殖生境中硫化物污染及控制技术研究进展

在近海集约化养殖过程中,水动力条件的改变、大量饵料的投放以及强烈的生物沉降导致底质生境有机污染严重,形成大面积缺氧区。在此环境中,含硫蛋白质降解和硫酸盐异化还原导致硫化物大量产生并扩散,成为海水养殖生态系统中危害程度仅次于氨氮的污染物,应该引起人们的足够重视。本文分析了近海养殖环境中硫化物产生的驱动力、硫化物在沉积物-水界面的扩散、硫化物污染控制技术及其优缺点,指出以铁氧化物为基础的化学控制技术和以硫氧化菌为基础的生物控制技术在硫化物污染控制持久性、可靠性等方面具有明显优势,在实际工程中具有应用潜力。     

Surface current response to wind and plumes in a bay-shape estuary of the eastern Yellow Sea: Ocean radar observation

Response of surface subtidal current to wind and outflow plume in the bay-shape estuary, which had been artificially made by the Samangeum reclamation dike with two sluices in the west coast of Korea, was examined using the ocean radar-derived current data obtained in the summer 2010. The southerly wind was dominant due to Asian summer monsoon and the outflow plume water was discharged by the gate operation of the Shinsi and Garyeok sluices separated by 11 km into the study area that are opened in a southwestward direction. The monthly-mean flow pattern consisted of the westward outflow currents around the two sluices, the along-dike currents between the two sluices and the northward currents in the outer bay. Based upon the complex correlations of subtidal current to wind and outflow jets we explained that the northward mean current in the outer bay be formed by both the southerly wind-driven current and the geostrophic current by mean pressure setup due to the Ekman transport and plume water accumulation in the inner bay, and the along-dike mean current may be induced by the southerly wind that generates on-dike currents in the central region of study area and leads to pressure setup toward the dike between the two sluices. Combination of outflow jets, wind and coastline configuration affects variations of subtidal surface current in the inner bay. Variability of subtidal current in the outer bay is dominated by wind variation. The southerly wind produced the northward current in the outer bay though the outflow plumes from the two sluices turned clockwise from the inner to the outer bay due to the geostrophic balance when the wind was calm. The wind factor was from 2% to 7% depending on the amount of freshwater outflow and wind speed. Occasionally, when plume water discharges were large and the southerly wind was stronger than 5 m/s, a large eddy with a closed loop current was produced off the Shinsi sluice.     

The tidal range energy potential of the West Coast of the United Kingdom

With concerns mounting over the UK’s energy future and the effects of climate change, it will soon become paramount that all viable sources of renewable energy are fully exploited. This study has examined the scope for reliable and fully predictable tidal electricity generation from the conjunctive operation of 5 major estuary barrages on the West Coast of the UK in an attempt to establish the potential scale of the extractable resources. Two levels of investigation have been undertaken: simple 0-D (‘two-tank’) modelling of barrage energy generation under different operational modes, using the hydraulic characteristics of turbine performance; and 2-D modelling of tidal hydrodynamics over a wide sea area in a computational grid incorporating the barrages with turbines and sluices. It has been demonstrated that more than 33TWh per year of electricity should be attainable, from 22GW of installed capacity, this representing close to 10% of present UK demand.     

Effects of Column Diameter on Setting Behavior of Dredged Slurry in Sedimentation Experiments

This article investigates the influence of dimensions of a settling column on the settling mode and the settling rate. End conditions of the settling stage in the hindered settling were also analyzed. It was found that the settling mode in a column with a smaller diameter tends to be consolidation settling. The effect of a settling column wall decreases with increasing column diameter, and it can be ignored provided the column diameter is larger than 14.5 centimeters. For the difference in initial water content, the settling behavior of the slurry develops a different sensitivity to the diameter effect. The influence of column diameter reduces as the initial water content of the slurry becomes higher. It is suggested that the internal diameter of the column used in a sedimentation experiment should be 14.5 centimeters.