淤长型泥质潮滩双凸形剖面形成机制  

Mechanisms for the evolution of double-convex cross-shore profile over accretional mudflats

作　　者：龚政[1,2] 张长宽[2] 陶建峰[1,2] 蔡辉[2] 

机构地区：[1]河海大学水文水资源与水利工程科学国家重点实验室,江苏南京210098 [2]河海大学港口海岸与近海工程学院,江苏南京210098

出　　处：《水科学进展》2013年第2期212-219,共8页Advances in Water Science

基　　金：国家自然科学基金资助项目(51009062;51179067)~~

摘　　要：以江苏中部淤长型泥质潮滩为例,建立了基于过程的潮滩动力地貌演变数学模型,研究了在沿岸潮流作用、供沙充分情况下双凸形潮滩横剖面形成机制。在向岸方向,流速自潮下带至低潮位线附近急速减小,潮间带区域流速则缓慢减小,泥沙在流速急变区域迅速堆积形成上凸点。潮下带中部在小潮期的淤积量大于大潮期冲刷量,总体淤积率较高;加之潮间带中部较弱的落潮流不足以将其上风处底沙掀动并向海输运,导致落潮后期潮下带上部含沙量小、沉积率相对较低,最终在潮下带中部形成下凸点。随着滩面淤长抬升,上、下凸点位置逐步向高、低潮位线附近移动。与前人关于双凸形剖面形成机制的定性分析成果相比,尚有不一致之处,需通过现场观测等进一步探讨。Taking the aceretional mudflats on the Jiangsu central coast as an example, a process-based morphodynam- ie numerical model is built. Mechanisms for the evolution of double-convex cross-shore profile are studied for the domi- nant long-shore tidal current and sufficient supplies of abundant sediments. The result shows that the flow velocity de- creases sharply from the subtidal fiats to the low waterline, and then decreases slowly landwards. The abrupt change in flow regime brings a high sedimentation rate along the low waterline, and forms the upper convex point in the area. During neap tides, the sedimentation rate will be greater than the erosion rate during spring tides over the middle sub- tidal flats, inducing a higher siltation rate. Furthermore, weak ebb current over the middle intertidal fiats is unable to transport sufficient upwind sediment seawards, which induces a lower sediment concentration and a lower siltation rate over the upper subtidal fiats during the final stage of ebb tides. Eventually, a low convex point will be formed over the middle subtidal fiats. With the accretion of tidal fiats, the levels of the upper and lower convex points will have a shift trend to high water level and low water level, respectively. Our results may not be in good agreement with other stud- ies. More field observations are needed to support further researches.

关 键 词：淤泥质潮滩 地貌动力学 凸形剖面 江苏海岸 潮汐不对称性 

分 类 号：TV122[水利工程—水文学及水资源]