珠江口门海堤堤型的选择

珠江口站地区面临南海、大陆岸线长４５７ｋｍ，遭受洪水。潮汐、台风的影响，河口滩涂 发育迅速，以约１００ｍ／ａ的速度向大海延伸。随着沿海地区的经济发展，滨海－２ｍ高程以上的滩涂的４万ｈｍ＾２正在和将要建堤围垦和开发利用，原有海堤也亟待加固提高，因此，对珠江口门坝有海堤堤型资料进行收集、整理，分析总结，选择经济可行的海堤堤型，具有重要的现实意义。文中收集了珠江口门的几种主要堤型，通过对各种堤基工程地质     

长江口不同河段表层细颗粒泥沙絮凝特性

利用长江口的现场观测资料分析河口不同区段表层细颗粒泥沙絮凝特性及其影响因素。结果表明:在河口上段水域,流速对絮凝表现为破坏作用,盐度是"制约"条件,流速和浊度对絮团影响明显,絮团平均粒径约为40.69mm,是分散粒径的4倍左右;口门最大浑浊带水域絮团峰值出现在憩流或者中等流速处,高盐度抑制、低盐度促进絮团生长,小潮时流速影响最明显、大潮时则是盐度,絮团平均粒径小潮为28.54mm、大潮35.17mm,是分散粒径2~3倍左右;北港口外,絮团生长或者破碎频繁,流速表现出促进作用,盐度有抑制作用,盐度对絮团影响最大,絮团平均粒径约为110.36mm,是分散粒径的18倍左右。     

Modeling sediment resuspension and transport induced by storm wind in Apalachicola Bay, USA

Sediment is an important environmental factor for aquatic ecosystem and oyster productivities of Apalachicola Bay located in Florida, USA. Based on the data analysis in this study, surface wind speed is highly correlated to the turbidity of water column, which results from sediment resuspension and transport in the Apalachicola Bay. In this paper, an application of a 3D sediment transport model to predict the wind-induced sediment transport in Apalachicola Bay is described. The sediment model is coupled with a 3D hydrodynamic module in the Environmental Fluid Dynamics Code (EFDC) model that provides information on estuarine circulation and salinity transport under normal temperature conditions. The hydrodynamic model was calibrated with field observations of water levels and salinity. The sediment transport model solves the transport equation with sources and sinks terms to describe sediment deposition and resuspension. The coupled hydrodynamic and sediment transport models were used to investigate wind-induced total suspended sediments (TSS) resuspension and transport in the bay. For the period June 1–July 30, 2005 two storm events with strong winds gave model results of TSS concentrations that compared well with the field observations. Model simulations reasonably reproduce the sudden increase of sediment concentrations during the storm events. Maximum sediment concentrations in the bay during the two storm events were 10 times or more than those in the pre-storm conditions. Spatial sediment transport from model simulations indicate active sediment resuspension and transport near areas of highly productive oyster beds. The model predictions of TSS and salinity can be used as inputs to an oyster dynamic model (Wang, H., Huang, W., Harwell, M., Edmiston, L., Johnson, E., Hsieh, P., Milla, K., Christensen, J., Stewart, J., Liu, X., 2008. Modeling eastern oyster population dynamics in response to changing environment in Apalachicola Bay, Florida. Journal of Ecological Modeling 211, 77–89) to support the ecological study of oyster growth and mortality in the aquatic ecosystem of Apalachicola Bay.     

考虑粘性泥沙运动的黄河口二维水沙输移数学模型

为研究黄河口的水沙输移规律,采用基于无结构三角网格下的有限体积法建立了平面二维水沙数学模型.模型中分别采用不同方法处理粘性和非粘性沙的输移源项,并引入经验证的粘性沙输移源项改进公式.采用已有的概化水槽冲淤试验资料对模型进行了验证,然后应用于1982年6月至1983年5月期间黄河口水沙输移的数值模拟,计算得到的潮位过程及冲淤量与实测资料符合较好,结果表明模型能够较好地模拟考虑粘性沙运动的黄河口非均匀沙不平衡输移.最后比较了不同泥沙输移源项处理方式对模拟结果的影响,计算表明在黄河口水沙输移数值模拟中需要采用非均匀沙模型并同时考虑粘性和非粘性泥沙的输移.     

黄河河口生态需水研究进展与展望

黄河河口生态需水包括河流生态需水、湿地生态需水和近海生态需水。系统梳理了近20年来黄河河口生态需水目标、需水类别和需水量计算结果;结合黄河河口演变特点,提出生态需水研究的重点和主要方向。河流生态需水以满足重要渔业物种生境为主,重点研究指示物种对天然径流量节律的响应特征,量化水文-生态响应关系,在某种程度上恢复自然水文情势的生态功能。湿地生态需水应深入研究植被、土壤、水体的水盐平衡和蒸散发规律,从植被和鸟类生态位的合理设计以及生物多样性维持出发构建生态系统结构,确定湿地合理规模。近海生态需水应研究入海冲淡水对渔业物种低盐产卵育幼场的塑造和维持机制,以及重要渔业物种习性、适宜营养盐水平与磷酸盐输送扩散机制。小浪底水库运用以来,利津断面径流量满足已有生态需水径流量各项研究成果要求的年份比例为37%～58%,春季经流过程经常缺乏流量脉冲。初步分析以湿地、河道鱼类和近海鱼类为主要目标的全年生态需水量为86亿m³,径流过程需要阶段性场次洪水。建议对小浪底水库调度方案进行多年优化调整,兼顾春季流量脉冲的塑造,在更大程度上满足河口生态需求。     

长江口一、二维嵌套水流盐度数学模型

建立了长江大通至河口大范围的一、二维嵌套水流盐度数学模型,其中大通至江阴采用一维河网数学模型,江阴至口外段采用一般曲线坐标系平面二维数学模型.采用长江大通至江阴以及江阴至河口段的实测资料对建立的一、二维模型进行了较系统的率定,结果表明:数学模型计算与实测资料均吻合较好,验证了该数学模型运用于长江口水流盐度数值模拟的可靠性,为下一步进行长江口盐水入侵研究奠定了基础.     

高浊度水体光学测量仪器的比较与验证

利用2017年冬季航次的现场光谱测量数据以及同步 水文泥沙参数,讨论了ASD地物光谱仪和Hypersas海面光谱仪两种光学 测量仪器在长江口局地高浊度水域所测光谱数据的差异情况。结果表 明,Hypersas光谱仪所测的光谱值在整体上 比ASD光谱仪的高;当积分时间 为34 ms时,两者的差异最小,其在412 nm、443 nm、 490 nm、510 nm、 531 nm、555 nm、 670 nm和750 nm各个典型波段的平均相对差异值 分别为22.70%、18.73%、15.01%、 14.07%、13.05%、 11.93%、9.58%和9.85%。 通过分析和对比两组数据与同步实测的悬沙浓度数据的相关性以及 拟合精度可以发现,在局地模式下,ASD光谱仪所测的悬沙浓度 建模精度(R2=0.78)比Hypersas光谱仪的(R2=0.67)高。     

Castles and Pavilions: Creating New Hybrid Places of Exchange

Tom Holbrook , Director at architecture and urban design practice 5th Studio, describes two projects in the south of England that respond spatially to the needs of ‘the knowledge economy’. The first is the River Lea Park, to the east of London, which promotes open connectivity between people in a post- industrial landscape; and the second is the Creative Exchange in St Neots, Cambridgeshire, a building designed to accommodate local enterprise. Both are designed to redirect social and economic activities, supporting creative swarming, and establishing what Stafford Beer has coined as ‘platforms for change’.     

Environmental studies on impacts of dredging

The coastal zone acts as a major interface between the ocean and continents. Harbours located in this zone face grave problems from sedimentation, which is a global issue for most of the harbours of the world. Dredging which counter acts sedimentation, brings about innumerable environmental impacts — both positive and negative. As a case study, this paper reports the impacts of dredging conducted at Cochin harbour which is the second largest port along the west coast of India; this port is a nodal center in trade and commerce connecting south east Asia to European sector. The harbour operation mainly depends on maintenance form of dredging bringing about impacts which have both direct and indirect effects in the long term. The important parameters selected for this study are salinity, current, extinction coefficient, turbidity, nutrients, chlorophyll and bottom fauna. An assessment is made on both positive and negative impacts which indicate rise in turbidity, changes in nutrient content and biota. The current practice on dredging is conducive to harbour operations, regulating the material made available to the near shore areas and highlights the possible venues for utilization of spoil for reclamation of land and wetland development. A flow chart identifies the areas vulnerable to impacts arising out of dredging and its consequential environmental issues.