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21.
磨刀门拦门沙区域枯季波流共同作用近底切应力和泥沙运动研究 总被引：2，自引：1，他引：1
On the basis of the measurement data pertaining to waves, current, and sediment in February 2012 in the mouth bar of the Modaomen Estuary, the Soulsby formulae with an iterative method are applied to calculating bottom shear stresses （BSS） and their effect on a sediment resuspension. Swell induced BSS have been found to be the most important part of the BSS. In this study, the correlation coefficient between a wavecurrent shear stress and SSC is 0.86, and that between current shear stresses and SSC is only 0.40. The peaks of the SSC are consistent with the height and the BSS of the swell. The swell is the main mechanism for the sediment re-suspension, and the tidal current effect on sediment re-suspension is small. The peaks of the SSC are centered on the high tidal level, and the flood tide enhances the wave shear stresses and the SSC near the bottom. The critical shear stress for sediment re-suspension at the observation station is between 0.20 and 0.30 N/m2. Tidal currents are too weak to stir up the bottom sediment into the flow, but a WCI （wave-current interaction） is strong enough to re-suspend the coarse sediment. 相似文献
22.
珠江口磨刀门月际尺度地貌演变研究 总被引：1，自引：1，他引：0
本文基于二维波流耦合泥沙数学模型对磨刀门河口月际尺度地貌演变进行了模拟研究。结果表明:（1）枯季，无波浪作用下，磨刀门河口总体呈淤积状态；波流耦合后，磨刀门河口整体由淤积转为以冲刷为主。洪季，无波浪作用下，磨刀门河口除西汊外均呈淤积状态；波流耦合后，拦门沙内坡与中心区转为冲刷状态，整体仍以淤积为主，但总淤积量减少；（2）月际尺度上，地貌变化幅度为厘米级，洪枯季具有明显差异。不考虑波浪作用下，磨刀门河口洪、枯季均以淤积为主，但洪季淤积幅度更大；波流耦合后，磨刀门河口呈洪淤枯冲的格局；（3）空间上，拦门沙外坡洪淤枯冲，拦门沙顶洪季淤积、枯季变化不大，内坡洪枯季均为冲刷。此外，拦门沙内坡以径潮流作用产生的底切应力为主，外坡以波浪作用引起的底切应力为主。 相似文献
23.
A long-term numerical model of morphodynamic evolution and its application to the Modaomen Estuary 总被引：1，自引：0，他引：1
Because of the influence of human activities,the evolution of the Modaomen Estuary is no longer a purely natural process.We used a long-term morphodynamic model(PRD-LTMM-10) to study the evolution of the estuary from 1977 to 1988.The model incorporated modules for riprap-siltation promotion and waterway dredging.The model can simulate the morphodynamic evolutionary processes occurring in the Modaomen Estuary during the period of interest.We were able to isolate the long-term influences of various human engineering activities and the roles of natural factors in estuarine evolution.The governance projects had the largest effect on the natural development of the estuary,resulting in larger siltation on the west side.Installation of riprap and reclamation of submerged land resulted in scouring of the main Hengzhou Channel causing deep trough out-shift.Severe siltation narrowed the upper end of the Longshiku Deep Trough. 相似文献
24.
根据2003年夏季采集的37个磨刀门河口表层沉积物样品,对其中7种阴阳离子(K 、Na 、Ca2 、Mg2 、Cl-、HCO3-、SO42-)的含量及分布特征进行了分析,结果表明,阳离子和阴离子的最大值一般都出现在外海,呈现出由口内河床-拦门沙地区-外海逐渐增大的趋势;其次是拦门沙附近,阴阳离子的含量都普遍高于其他地区,阳离子互相之间具有良好的相关性,阳离子与Cl-以及SO42-这两种阴离子的相关性较好,此外,Cl-和SO42-这两种阴离子之间也具有较好的相关性,其影响因素主要是磨刀门河口的水体盐度、沉积物粒度、河口咸淡水混合作用、海洋动力作用和物质来源等。 相似文献
25.
珠江口磨刀门泥沙絮凝特征 总被引：3，自引：3，他引：0
本文利用激光粒度仪实测得到珠江口磨刀门河口2013年夏季悬浮泥沙现场絮凝及絮凝体特征,同时对比悬沙分散粒径和含沙量,研究表明:悬沙分散粒径平均值为27.9μm,现场实测絮团粒径平均值为91.6μm,表明磨刀门口外的悬浮泥沙絮凝现象显著;实测絮团平均粒径变化范围为13.0~273.8μm,小潮期间絮团粒径平均值为131.5μm,大于大潮平均值76.9μm;絮凝体粒径在垂向上的变化表现为由表及底先变大再变小。絮团体积浓度、沉速与粒径的关系在不同情况下有差异,体积浓度和絮团粒径在表层和中层有明显正相关关系,絮团沉速在大潮时刻随着粒径的增大而增大。综合分析影响絮凝的因素,得知在珠江口盐度对于絮团大小影响不明显;而流速大小的差异是影响大小潮之间絮团大小不同的主要因素。研究结果有助于了解珠江口细颗粒泥沙输移特性和相关生物化学过程。 相似文献
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27.
珠江磨刀门河口径潮动力耦合条件下余水位的多时空尺度分析 总被引：3，自引：3，他引：0
本文通过构建径潮动力耦合条件下潮波传播的一维水动力解析模型，从理论机制上探讨珠江磨刀门河口径潮动力非线性作用下余水位的多时空尺度变化。结果表明:余水位变化呈现明显的大小潮和洪枯季变化，枯季余水位大小潮的变化幅度介于0~0.4 m，而洪季余水位与上游径流紧密相关，增幅大枯季一个量级（介于0~6 m）；解析模型可分离控制余水位变化的3个主要因素，即径流、潮流和径潮相互作用因子，计算结果表明河口不同区段余水位的主控因素有明显的洪枯季变化，上游段，枯季余水位受径潮相互作用因子控制，洪季受径流因子控制；枯季下游段余水位受潮流控制，而洪季余水位主要受径潮相互作用因子控制。 相似文献
28.
珠江河口磨刀门水道枯季盐水入侵特性分析 总被引：1，自引：0，他引：1
为探讨磨刀门水道潮流和盐度的三维分布特性,本文建立了磨刀门水道的三维潮流和盐度数值模型,采用2009年枯季磨刀门水道实测潮流和盐度资料对模型参数进行率定和验证。结果显示,枯季由于上游径流量小,磨刀门水道总体涨、落潮流速都不大,表层总体涨潮平均流速都在0.5 m/s以内,总体落潮平均流速在0.8 m/s以内;底层总体涨落潮平均流速都在0.5 m/s以内;从盐度的平面分布来看,磨刀门水道近口门河段总体呈现涨潮时水道东侧盐度高于西侧,落潮时东侧盐度小于西侧的趋势。大潮和中潮期间,落潮时盐水向上游的入侵距离反而较涨潮时更远,主要原因是,落潮时的底层盐水向上游的补偿流动以及地形阻拦形成更为强烈的紊动扩散。潮汐动力弱(小潮)时,整个水道内水流流速很小,流态平缓,紊动较弱,总体仍呈现涨潮时入侵距离大于落潮,显示枯季磨刀门水道盐水入侵的主要影响因素取决于地形和潮动力。 相似文献
29.
The dynamic feature of the Modaomen Estuary (ME) in the Pearl River Delta in southern China has been the subject of extensive research. In previous studies, wave–current interaction (WCI) was often neglected due to its complexity. This study uses a coupled hydrodynamic module TELEMAC-2D and wave propagation module TOMAWAC in the TELEMAC-Mascaret modeling system to quantify the effects of WCI on the hydrodynamics in the ME. The coupled wave and current modeling system was well validated against the field measurements at selected locations. The model results show that WCI varies with the seasonal change in runoff in the ME. The effect of waves on the currents is insignificant during the wet season with a current change of no more than 0.07 m/s; but, in contrast, the currents have a noticeable effect on waves. However, during the dry season, the interactions of waves and currents on each other are found to be equally significant. When wave model and current model are coupled, the velocity could increase up to a maximum of 0.30 m/s and decrease up to a maximum of 0.17 m/s. WCI is greatly affected by the propagation directions of wave and current in both seasons. Generally, wave height decreases and current increases for a following wave and current; wave height increases and current decreases for an opposing wave and current. The effects of waves on currents change with the tide. Changes are larger during neap tide than during spring tide, and stronger during ebb tide than during flood tide. 相似文献
30.
磨刀门水道咸潮入侵及其变异分析 总被引：7，自引：1，他引：7
随着区域经济及人口的进一步增长,珠江三角洲磨刀门水道已成为江门、中山、珠海、澳门等城市重要的水源地,相应咸潮入侵对供水安全造成的危害也越来越严重。本文依据实测资料和现场调研,对磨刀门水道咸潮入侵的潮相变化、径流—咸潮的响应模式、风对咸潮入侵的影响及咸潮入侵的历史演变趋势及其变异、最小压咸流量及最佳压咸时机等进行了研究。研究结果表明,影响咸潮入侵的主要因素是径流,有利于咸潮入侵的风向为北风～东北风。以思贤滘流量(即马口水文站与三水水文站流量之和)为参照,为保障珠海、澳门供水安全,磨刀门水道最小压咸流量范围为2200-2700m3/s,平均流量为2450m3/s,最佳压咸补淡的时机为大潮转小潮期,也就是朔望(半月)周期的落潮期。 相似文献