GIS支持下近百年来闽江口海底地形地貌演变     

徐晓晖  陈坚  赖志坤 《台湾海峡》2009,28(4):577-585

利用ArcGIS建立了闽江口1913、1950、1975、1986、1999、2005年海底数字地形模型,在坐标系统和潮位基准面转换的基础上分析研究了闽江口的岸线、浅滩面积、海底冲淤和河口断面地形近百年来的变化特征．研究结果表明：①闽江口河道从1913年到2005年期间,梅花水道西段变窄,乌猪水道向东迁移,琅岐岛东岸淤积;梅花镇东侧的闽江口南岸岸线向前推进,但近年来推进速率明显减小．②梅花水道浅滩不断发育,闽江北支由单一的川石水道变成川石水道和壶江水道并存,并且闽江北支成为闽江入海泥沙的主通道．③1913—1950年间闽江口海底淤积较快,1913～1999年淤积速率逐渐减小,1986～1999年间出现净冲刷．④河口三角洲前缘在河口南部以侵蚀后退为主,河口区北部以进积为主．  相似文献   

Modelling time varying scouring at bed sills     

Matteo Tregnaghi  Andrea Marion  Andrea Bottacin‐Busolin  Simon J. Tait 《地球表面变化过程与地形》2011,36(13):1761-1769

In this paper a modelling approach is presented to predict local scour under time varying flow conditions. The approach is validated using experimental data of unsteady scour at bed sills. The model is based on a number of hypotheses concerning the characteristics of the flow hydrograph, the temporal evolution of the scour and the geometry of the scour hole. A key assumption is that, at any time, the scour depth evolves at the same rate as in an equivalent steady flow. The assumption is supported by existing evidence of geometrical affinity and similarity of scour holes formed under different steady hydraulic conditions. Experimental data are presented that show the scour hole development downstream of bed sills due to flood hydrographs follow a predictable pattern. Numerical simulations are performed with the same input parameters used in the experimental tests but with no post‐simulation calibration. Comparison between the experimental and model results indicates good correspondence, especially in the rising limb of the flow hydrograph. This suggests that the underlying assumptions used in the modelling approach are appropriate. In principle, the approach is general and can be applied to a wide range of environments (e.g. bed sills, step‐pool systems) in which scouring at rapid bed elevation changes caused by time varying flows occurs, provided appropriate scaling information is available, and the scour response to steady flow conditions can be estimated. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

黄河下游游荡河段清水冲刷时期河床调整的复杂响应现象   总被引：1，自引：3，他引：1       下载免费PDF全文

许炯心 《水科学进展》2001,12(3):291-299

以1960～1962年三门峡水库下泄清水时期定位观测资料为基础,研究了清水冲刷条件下黄河下游河床调整过程。结果表明,由于河床边界条件的不同,游荡段的上段(铁谢-桃花峪)和下段(桃花峪-辛寨)的河床调整过程表现出明显的差异,由此可以划分两种不同的调整方式和复杂响应类型:河岸抗冲性强、河床组成物质较粗的河段,河床调整及其中的复杂响应主要与水力参数有关;河岸抗冲性弱、河床物质组成较细的河段,河床调整中的复杂响应主要与河床形态有关。研究所得结论,可为预测小浪底水库建成后黄河下游河床演变趋势提供参考。  相似文献   

Micromorphology of ice keel scour in pebbly sandy mud and fine‐grained sands: Scarborough Bluffs,Ontario, Canada          下载免费PDF全文

Lorna D. Linch  Jaap J. M. van der Meer 《Sedimentology》2015,62(1):110-129

The keels of icebergs and ice‐pressure ridges plough through unconsolidated sea/lake sediments gouging out long grooves known as ice keel scour marks. Although the surface and (more recently) subsurface morphology of scours are well‐documented, little is known of the effect of grain size on the detectability, style and intensity of sub‐scour deformation. This investigation macroscopically and microscopically (two‐dimensional thin sections) examines suspected ice keel scour in: (i) glaciolacustrine pebbly sandy mud and (ii) fine‐grained sands at Scarborough Bluffs, Ontario, Canada. In this investigation, there is an almost identical suite of deformation structures (individual structures and overprinted structural patterns) to those identified in iceberg‐scoured clays from former Glacial Lake Agassiz (Manitoba, Canada); this confirms that deformation in the pebbly sandy mud and fine‐grained sands at Scarborough Bluffs is likely to be indicative of ice keel scour. Discrete differences in the detectability, style and intensity of deformation between the Scarborough Bluffs and Glacial Lake Agassiz sediments are probably a function of grain size in response to ice keel scour. This research provides additional information on the types of structures that are associated with sediment deformation by processes of ice keel scour in a variety of grain sizes. This information is particularly valuable to inform palaeoenvironmental reconstruction and offshore engineering in areas where ice keel scour occurs in a variety of grain sizes. It also demonstrates the potential value of micromorphology where, for example, the study of cores is necessary.  相似文献   

Numerical modeling of local scour due to submerged wall jets using a strict vertex-based,terrain conformal,moving-mesh technique in OpenFOAM     

《国际泥沙研究》2020,35(3):237-248

This study presents the implementation and validation of a new sediment-scour model with a strict vertex-based,terrain conformal,moving-mesh technique within the framework of OpenFOAM.OpenFOAM lacks the ability to simulate large-amplitude motion needed for analysis of sediment-scour problems,and,thus,its application normally is restricted to small-amplitude cases to prevent computational divergence due to mesh deterioration.The proposed simple,moving-mesh technique in OpenFOAM is implemented to overcome the shortcomings of the conventional automatic mesh-motion techniques in handling large-amplitude moving geometries.The model is used to simulate a simple case of prescribed boundary motion,a previous experiment in the literature,and a new laboratory experiment for local scour due to submerged wall jets.The results are compared with both the experimental and other numerical results.The comparisons demonstrate that the proposed model has the novel advantage of allowing for more severe topographic variations,and can provide more reliable predictions for the key characteristics and evolution of the bed profiles in wall jet scour problems.Furthermore,to improve the practice of modeling wall jet scour,various turbulence modeling approaches and bedload equations also are evaluated and compared.  相似文献   

FLUVIAL PROCESSES AND SEDIMENT SCOUR RATE OF THE YELLOW RIVER UNDER ACTION OF UNSTEADY FLOWS     

Yong-Nian XU Zhi-Yong LIANG  Thao-Yin WANG China Institute of Water Resources  Hydropower Research  Beijing  China. International Research  Training Center on Erosion  Sedimentation  Beijing  China. 《国际泥沙研究》2001,16(2)

1 wrsoooCTIoxThe Yeuow mver crtes a huge amoun of sedimcht and the noods often cause raPid and severeerosinn and dePOsihon. The channl bed of the YelOw mver often exPeriences degIadation in the mainchannel during fioods. In some cases vigorous erosion uP to l0 meters takes place in a shOrt Period oftiIn. Such phenomenon usually occurs in the ndddie reaChs of the Yelow mver and its tributaries suchas the Wdse mVer the Beiluohe mver etc. For examPle, th6 hyPenconcentraed nood in July l…  相似文献   

辽河油田太—葵管道路由区海底冲淤变化研究     

边淑华  杨玉娣  魏宏伟  亓发庆  李晓娟 《海岸工程》2007,26(2):19-25

辽河油田太—葵管道路由区位于辽东湾顶潮汐水道区。通过不同时期实测水深对比,得出该区海底冲淤变化趋势:海区总体呈微淤态势,潮汐水道两侧浅滩淤积,两侧边坡一侧侵蚀另一侧淤积,发生平面迁移。管道路由一线蚀淤幅度较小,一般不超过0.5 m,最大侵蚀区发生在水道底和两侧边坡,是海底输油管道容易冲刷悬空的潜在危险区,需采取深埋措施提高安全性。  相似文献   

粉砂质海床上建筑物周围局部冲刷的系列模型延伸法研究   总被引：3，自引：0，他引：3       下载免费PDF全文

韩西军  曹祖德  杨树森 《海洋学报》2007,29(1):150-154

系统介绍了泥沙冲刷系列模型试验的相似理论,同时利用系列模型试验结果对相似关系式中的参数进行了分析,指出:(1)系列模型试验是利用几何及水流运动相似而泥沙运动不相似的模型取得试验成果的一种有效方法;(2)采用原型沙进行系列模型试验也是适宜的;(3)系列模型试验只要作两个比尺差距较大的模型就能通过外延取得所需要的试验成果,并能保证一定的精度.  相似文献   

胜利油田孤东海堤保滩促淤工程二维潮流数值模拟研究   总被引：1，自引：0，他引：1  

刘清涛  蒲高军  刘芸 《海洋科学进展》2003,21(2):188-193

以胜利油田孤东海堤保滩促淤工程为实例，采用二维潮流数值模拟方法，利用实测流速资料对该海区进行潮流计算，对所提出的不同工程方案进行比较，并分析其促淤效果，在此基础上给出工程方案的推荐结论。  相似文献   

Estimation of pile group scour using adaptive neuro-fuzzy approach   总被引：4，自引：0，他引：4  

S.M. Bateni  D.-S. Jeng   《Ocean Engineering》2007,34(8-9):1344-1354

An accurate estimation of scour depth around piles is important for coastal and ocean engineers involved in the design of marine structures. Owing to the complexity of the problem, most conventional approaches are often unable to provide sufficiently accurate results. In this paper, an alternative attempt is made herein to develop adaptive neuro-fuzzy inference system (ANFIS) models for predicting scour depth as well as scour width for a group of piles supporting a pier. The ANFIS model provides the system identification and interpretability of the fuzzy models and the learning capability of neural networks in a single system. Two combinations of input data were used in the analyses to predict scour depth: the first input combination involves dimensional parameters such as wave height, wave period, and water depth, while the second combination contains nondimensional numbers including the Reynolds number, the Keulegan–Carpenter number, the Shields parameter and the sediment number. The test results show that ANFIS performs better than the existing empirical formulae. The ANFIS predicts scour depth better when it is trained with the original (dimensional) rather than the nondimensional data. The depth of scour was predicted more accurately than its width. A sensitivity analysis showed that scour depth is governed mainly by the Keulegan–Carpenter number, and wave height has a greater influence on scour depth than the other independent parameters.  相似文献