风暴对滨海湿地潮沟水沙输运的影响——以长江口崇明东滩为例

为了探知风暴事件对滨海湿地潮沟水沙输运的影响，分别于平静天气和风暴天气(“摩羯”和“温比亚”台风)条件下，在崇明东滩一典型潮沟进行了现场水沙数据观测。结果表明：台风期间近岸平均风速较平静天气增大3~4倍，有效波高增大7~15倍，盐沼前缘光滩和潮沟遭受强烈侵蚀，潮滩表层沉积物粗化1~2.1倍，水体悬沙浓度增大3~11倍，潮沟潮周期单宽泥沙输运通量增大4~33倍, 单宽泥沙净输沙量增大8~17倍。风暴天气下，潮沟水沙输运呈现“大进大出”的特点，在盐沼潮滩内受盐沼植被消波、缓流和捕沙作用下，潮周期内单宽泥沙净通量指向盐沼潮滩，促进了盐沼滩内部泥沙的淤积。

IMPACTS OF STORM ON WATER AND SEDIMENT TRANSPORTATION THROUGH TIDAL CREEKS OF COASTAL WETLANDS: A CASE FROM EASTERN CHONGMING TIDAL FLAT,YANGTZE ESTUARY

In order to investigate the impacts of storm event on water and sediment transportations through tidal creeks of coastal wetlands, in-situ measurements were carried out in a typical tidal creek in the Eastern Chongming tidal flat under both the conditions of calm weather and stormy weather (during the typhoons of "Yagi" and "Rumbia"). The facts show that the average wind speed near the shore during typhoon period was 3~4 times higher than that in calm weather, while the significant wave height increased by 7~15 times. During the storm event, mudflat and saltmarsh at the tidal front were strongly eroded, surface sediment coarsened for 1~2.1 times, suspended sediment concentration increased by 3~11 times, the sediment transport flux per unit width for each tidal cycle increased by 4~33 times, and the net sediment flux per unit width for each tidal cycle increased by 8~17 times. The transportation of water and sediment during flood and ebb tides under storm weather conditions were much greater than those under calm weather conditions. The net sediment flux was moving towards saltmarsh flats and deposit there due to attenuation of wave, retarding of current flow and trapping of mud.