黄河水下三角洲北部区域海底地形冲淤变化研究

为了明确黄河水下三角洲北部区域海洋动力对海底地形变化的影响,采用2009年黄河水下三角洲北部区域高精度水深地形资料,与2004年水深地形资料进行对比分析。同时,利用2009年对表层沉积物的粒度分析,结合该区域的水文潮流特征,对该海区悬移质泥砂引起的冲淤变化进行了预测。研究结果表明该区域经过多年的冲淤调整正逐渐达到冲淤平衡,形成稳定的粉砂淤泥质海岸,但在大风大浪引起的恶劣海洋作用下,本区仍然经历着缓慢的冲刷过程。埕北海域在CB151平台附近形成一个冲刷中心,冲刷深度超过1 m;孤东海堤外侧海域,自陆地向等深线12 m区域均发生轻微冲刷作用,尤其是海堤根部,由于波浪的累加作用,冲刷最为明显,最大冲刷深度可达1.5 m以上。

Bottom Topographic Changes North of the Yellow River Underwater Delta by Scouring and Silting

In order to determine the marine dynamical effects on the bottom topographic changes,the highly-accurate bathymetric data obtained in the sea area north of the Yellow River underwater in 2009 are compared with the data in 2004.In addition,the surface sedimentary grain-size data obtained in 2009 are used and conbined with the knowledge of the hydrographic and tidal charateristics in this sea area to predict the topographic variation caused by the scouring and silting of the suspensible mud and sand.It is shown in the study results that generally a state of equilibrium between the scouring and the silting appears to some extent at present in the studied area after scouring sometimes and silting in other times the topography has been changable for years and years, and a stable coastal area made of silty sand is somehow formed.However the sea area seems to be scoured in a very slow process due to actions of rough sea occarionally caused by strongwind.A scoured area,deeper than 1 m,is located at the place adjacent to Platform CB151 in the Chengbei area.And a slightly scouring action takes place in a sea area seaward from the Gudong dyke up to the 12 m isobath.Especially sediments as deep as 1.5 m have been obviously scoured away in the sea area adjacont to the dyke foundation due to the many times wave actions.