摘要
来自岸外辐射沙脊群和废黄河口的细颗粒沉积物供给使江苏中部海岸潮滩快速淤长,其潮间带沉积速率以1～5cm·a^-1为特征值.针对该特征值的控制机理问题,本文以王港潮滩为原型,用数值实验方法重现了滩面悬沙输运格局,通过沉积连续方程模拟了海岸剖面上沉积速率的分布特征.结果表明细颗粒物质在潮间带上部强烈堆积,在给定的模拟条件下,最大沉积速率值与上述特征值相当;潮滩沉积速率随岸外水体悬沙浓度的降低而降低,＂由淤转冲＂的临界悬沙浓度值约为0.4kg·m^-3,这表明若沉积物供应下降至一定水平,潮滩剖面将不能维持稳定.模拟结果显示,虽然目前江苏中部海岸潮滩呈淤长状态,但未来将面临因物源匮乏而转为侵蚀的风险,这对于海岸防护和生态系统保护是一个新的挑战.
The supply of fine-grained sediments from the old Yellow River delta and the offshore radial tidal sand ridges has resulted in the formation of extensive tidal flats on the central Jiangsu coast,with characteristic deposition rates of 1-5cm·a^-1 over the intertidal zone.Using the Wanggang coast as a case study area,suspended sediment transport is evaluated by numerical experimental methods.Based on the sediment continuity equation,the horizontal distribution pattern of the deposition rate over the tidal flat is derived.The analytical results show that,under the given conditions for the numerical experiments,rapid accretion by fine-grained sediment occurs on the upper tidal flat,with the deposition rate being of the same order of magnitude as the observed values.Furthermore,the deposition rate is shown to decrease in response to a reduction of suspended sediment concentration in offshore waters;a critical suspended sediment concentration representing the transformation from accretion to erosion is estimated to be0.4kg·m^-3.These observations imply that if the sediment supply is cut off,then the profile of the tidal flat will notremain stable.Therefore,although the central Jiangsu coastlines are still advancing towards the sea at the present stage,there is a risk of coastal recession in the near future because of reduced sediment supply,which may become a new challenge for coastal defense and ecosystem reconstruction.
出处
《南京大学学报（自然科学版）》
CAS
CSCD
北大核心
2014年第5期656-665,共10页
Journal of Nanjing University（Natural Science）
基金
海洋公益性行业科研专项(201005006)
江苏省基础研究计划项目(BK2011012)
国家大学生创新训练项目(G1310284006
G1210284010)
关键词
沉积速率
潮滩
悬沙输运
物源供给
数值实验方法
deposition rate
tidal flats
suspended sediment transport
sedimentary supply
numerical experiments
