【作者】 贾宁；

【导师】 韩树宗；

【作者基本信息】 中国海洋大学 ， 物理海洋学， 2011， 硕士

【摘要】 海岸带是大陆和海洋的交汇处,海洋与陆地最接近的区域。在这一区域各种环境因素众多,水动力系统复杂。由于海岸、河口区域水深较浅,浪、流是主要的动力因素。波浪和潮流共同作用对海岸带地区的泥沙运动有十分重要影响。本文采用三维水动力泥沙模型ECOMSED和SWAN波浪模型分析胶州湾海域浪流共同作用下的泥沙输运情况。本文以在胶州湾海域的综合性观测资料为基础,分析胶州湾海域内泥沙和水文的分布特征;考虑潮流作用、波浪作用、泥沙底质分布特征,采用SWAN波浪模式和ECOMSED水动力模式联合计算并验证该模式在胶州湾泥沙输运模拟中的适用性。数值模拟潮流作用、潮流和波浪共同作用下的胶州湾海域悬沙运动,并对其机制进行分析,并对两者的结果做了对比。本文的工作主要有,查找有关胶州湾的历史资料和文献,阅读相关的水动力和波浪数值模拟文章,对泥沙数值模拟的研究进展和现状进行总结;对胶州湾海域内的波浪进行模拟,采用三重嵌套方式进行计算,计算出与实际情况较为接近的波浪场,得出胶州湾海域的有效波高和周期等波要素的发展变化过程;采用ECOMSED模式模拟胶州湾的水动力场,开边界设在湾口附近,将附近验潮站的六个主要分潮(S2,M2,N2,K1,P1,O1)的调和常数作为动力驱动,通过与实际观测数据的对比分析,模拟出与实际情况较为接近的潮汐潮流场,证明了ECOMSED模型在胶州湾海域的适用性;联合SWAN波浪模型计算出的波浪要素及ECOMSED模型模拟出的水动力场,对胶州湾海域的悬浮泥沙进行模拟,得到浪流共同作用下的胶州湾悬浮泥沙分布及随水流运动规律,分析浪对泥沙的影响。计算结果显示,ECOMSED水动力模型能够较好地模拟胶州湾海域的潮汐潮流场,潮汐类型表现出典型的半日潮性质。SWAN波浪模型模拟结果与实测资料吻合程度较高,模型能够成功模拟胶州湾海域中的波浪场。计算结果发现胶州湾内的波浪普遍较小,多年波浪测量数据发现胶州湾长期没有大浪,这与数值模拟结果一致。流速是影响悬沙浓度的重要因素,仅考虑潮流作用下,悬沙等浓度值等值线基本平行于等深线,随水深增加悬沙浓度逐渐减小,流速是影响悬沙浓度的主要因素。胶州湾海域整体悬沙浓度较低,大部分海域内在10mg/L至50mg/L范围内,大于50mg/L的悬沙浓度范围主要分布在近岸海域,与5m等深线以浅的范围重合,每方海水中大约有几十克物质。考虑波浪和潮流因素共同影响作用,同仅考虑纯天文潮流影响类似,悬沙浓度值等值线基本平行于等深线,随水深的增大悬沙浓度逐渐减小,胶州湾海域整体悬沙浓度较低,根据数值模拟结果显示,大部分海域内的悬沙浓度在10mg/L至100mg/L范围内,大于100mg/L的悬沙浓度范围主要分布在近岸海域,与5m等深线以浅的范围重合,在近岸海域,波浪对泥沙运动的影响较为显著,波浪作用可以到达海底。同时考虑波浪和潮流作用对泥沙运动的影响,胶州湾海域内的悬沙浓度值在近岸海域增加较为明显,水深较大地区浓度值总体较低,即每方海水中大约有几十到一百多克物质。在纯潮流作用下,底应力较小,不足以使底床沉积的泥沙起动进入水体,当加入波浪作用时,波浪通过不断对近底水体扰动、搅拌产生较大的湍流,增加了床面剪切应力,拖曳力的增加也会影响近岸区域的流场,从而影响对近岸海域的悬沙含量、改变海岸海底地貌。浪流共同作用下,在近岸海域水体中的悬沙浓度增加,比纯潮流作用下的泥沙浓度提高2%～68%,平均提高14%。更多还原

【Abstract】 Coastal region is the intersection of land and sea. In this region there are a number of environmental factors, and the hydrodynamic system is complex. In the coastal, estuarine areas,the wave and tide are the main dynamic factor with the change of water depth. Wave and tidal interaction is very necessary on the study of sediment transport. This paper analyzes the wave and tide interactional sediment transport mechanisms using ECOMSED 3-dimensional hydrodynamic and sediment model and SWAN wave model in Jiaozhou Bay.In this paper, it analyzes the distribution of sediment concentration and hydrological characteristics based on a lot of observations in Jiaozhou Bay. The sediment transport applicability of SWAN and ECOMSED coupled model was validated by considering tidal influence, wave influence and sediment distribution. The sediment transport under tidal current, ocean waves was simulated and the influence to transport by them was studied respectively.The main work in the paper is described as follows. It summarized the progress in numerical simulation of sediment, ocean waves and sediment transport under tidal current and waves. Ocean waves simulation in Jiaozhou Bay was constructed by SWAN model by adopting triple-nested manner. It got the wave parameters and their evolution such as significant wave height and mean periods. The harmonic constants S2, M2, N2, K1, P1, O1 were calculated by the tide gauge stations nearby, which were given as the boundary conditions of ECOMSED model. It showed a good performance of ECOMSED from the comparisons with observations of tidal current and water level. In order to understand the role of the waves in the sediment transport, the simulated wave elements were added to the ECOMSED sediment module, which give a comprehensive simulation of sediment evolution. The results show that ECOMSED hydrodynamic model give a good simulation of water level and tidal current in Jiaozhou Bay, where the tidal type is typical semidiurnal nature. The significant wave height derived from Jason-1 is similar to the simulated results by SWAN. It shows that Jiaozhou Bay is always in smooth sea states, which is correspond to the observations.Current speed plays an important role in the suspended sediment concentration evolution. Only considering the action of current, the contour lines of suspended sediment concentration are parallel to contour lines of water depth. The concentration decreases gradually when the water depth becomes deeper and most of the suspended sediment concentration is 10mg/~50mg/L in the deep water. The suspended sediment concentration is greater below 5m isobaths nearshore. Overall, the suspended sediment under the action of tidal current is low, which is about dozens of grams per cubic meter.Some characteristics under joint influence of wave and tidal current are similar to that under tidal current. The sediment concentration contours are parallel to depth contours and the suspended sediment concentration decreases accompany with the deeper of water depth. The current plays an important role in the sediment transport. The simulated results shows that most of the suspended sediment concentration is 10mg/L~100mg/L. The suspended sediment concentration is greater below 5m isobaths nearshore. Overall, the suspended sediment concentration is higher than under the action of tidal current, which is about dozens to 100 grams per cubic meter.In the case of wind waves, the suspended sediment concentration distribution near-shore will change significantly. It becomes greater than simply under the tidal current. That means that ocean waves are an important factor in coastal sediment transport. The joint influence by wave and current will have a rise about 2%~68% in the suspended sediment concentration. The average value is abou 14%.更多还原