High-resolution data collection for analysis of sediment dynamic processes associatedwith combined current-wave action over intertidal flats  

作　　者：WANG Yaping GAO Shu JIA Jianjun 

机构地区：[1]Key Laboratory for Coast and Island Development, Ministry of Education, Nanjing University, Nanjing 210093, China [2]Key Laboratory of Submarine Geo-Sciences, Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China

出　　处：《Chinese Science Bulletin》2006年第7期866-877,共12页

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.40576040,40231010 and 40206006).

摘　　要：An MIDAS-400 Customised Data Ac- quisition System was deployed to obtain current ve- locity and suspended sediment concentration profiles over the intertidal flat at Wanggang, on the Jiangsu coast (China). At the same time, seawater tempera- ture, conductivity and pressure were measured. Us- ing a data sampling rate of 4 Hz, the high-frequency pressure signals in response to water surface fluc- tuations were recorded and subsequently trans- formed into wave parameters. The analytical results show that the apparent bed roughness length has a magnitude close to the height of sand ripples, which is much larger than the grain size diameter. The bot- tom shear stress associated with current-wave in- teraction is higher than the tidally-induced stress and intensified turbulent mixing and resuspension. Fur- thermore, several suspended sediment concentration peaks occurred during a tidal cycle, which can be related to strong turbulence near the bed caused by frontal tidal currents and the enhanced resuspension; advection and extreme weather conditions (e. g. storms and strong winds) also played an important role. Finally, large net suspended sediment fluxes were observed to present when the flood or ebb currents prolonged, i.e. the flow became quasi-unid- irectional during a tidal cycle. In general, the MIDAS- 400 is a suitable tool for high-resolution data collec- tion for the situations of combined current-wave ac- tion over intertidal flats; the data obtained can be used to analyze the processes and mechanisms of material transport.An MIDAS-400 Customised Data Acquisition System was deployed to obtain current velocity and suspended sediment concentration profiles over the intertidal flat at Wanggang, on the Jiangsu coast （China）. At the same time, seawater temperature, conductivity and pressure were measured. Using a data sampling rate of 4 Hz, the high-frequency pressure signals in response to water surface fluctuations were recorded and subsequently transformed into wave parameters. The analytical results show that the apparent bed roughness length has a magnitude close to the height of sand ripples, which is much larger than the grain size diameter. The bottom shear stress associated with current-wave interaction is higher than the tidally-induced stress and intensified turbulent mixing and resuspension. Furthermore, several suspended sediment concentration peaks occurred during a tidal cycle, which can be related to strong turbulence near the bed caused by frontal tidal currents and the enhanced resuspension; advection and extreme weather conditions （e. g. storms and strong winds） also played an important role. Finally, large net suspended sediment fluxes were observed to present when the flood or ebb currents prolonged, i.e. the flow became quasi-unidirectional during a tidal cycle. In general, the MIDAS- 400 is a suitable tool for high-resolution data collection for the situations of combined current-wave action over intertidal flats; the data obtained can be used to analyze the processes and mechanisms of material transport.

关 键 词：高分辨率数据收集 底板压力 悬浮 沉积 浓缩 潮间带 

分 类 号：P7[天文地球—海洋科学]