黄河三角洲飞雁滩表层沉积物对水动力的响应
RESPONSE OF COASTAL SEDIMENT TO THE HYDRODYNAMIC CONDITIONS IN THE FEIYAN BEACH IN THE NORTHERN YELLOW RIVER DELTA
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摘要: 利用2004年4月所采集的104个表层沉积物样品粒度分析资料及实测水文数据,探讨了空间上黄河三角洲飞雁滩表层沉积物对潮流及波浪等水动力的响应过程,以及该区域表层沉积物的输移趋势和补给来源问题。结果表明:(1)该区潮流掀沙作用范围包括潮沟前部约8~12 m水深和1~5 m水深内水下潮沟区域,以及海堤前部1.7~17 m水深范围,而对于波浪动力作用,其掀沙范围除受沉积物空间分布格局控制外,还取决于其波能的大小和实际水深,且该区所能够承受最大波浪波高不超过3 m;(2)该区域沉积物补给来源主要为波浪动力尤其是大风浪引起的风暴潮所起动并导致其离岸输移的潮间带甚至潮上带较细颗粒泥沙;(3)总体上,除潮沟入口处外,该区域表层沉积物以离岸输移为主。Abstract: Since the terminal reach of the Yellow River shifted to Qingshuigou in 1976, northern coast of the Yellow River delta has been wholly faced with an erosion situation due to the discontinuity of the river-supplied sediment, which has seriously threatened the safety of ecosystem environment and the Shengli Oilfield in this area. A comprehensive analysis is conducted based on the data of wave, tidal current and bedload which was observed during March-September 1987(wave) and April 2004(tidal current and bedload). Laws of the coastal sediment movement and response to the hydrodynamic conditions, the sediment transportation and the sediment supply have been studied and discussed. Results are as follows:①Tidal current can start up sediments in part of tidal-creek areas and rages between isobaths of 1.7m and 17m. And the sediment-carrying capability of wave is determined by the sediment distribution, wave energy and water depth. Also in the study area, sediments can bear wave motivity not more than waves with 3m height. ②The finer sediment which comes from the intertidal zone is an important supplement to the coastal bedload which lies in front of the tidal creek. It plays a significant role in maintaining the coast equilibrium profile or decelerating the erosion. ③Generally, sediments are mainly transported towards offshore, except in the tidal-creek inlets.