异质潮滩波浪衰减特性研究——以长江口崇明东滩为例

Wave attenuation on tidal flat with particular sediment-case study:Eastern Chongming Island,Yangtze Estuary

为研究不同底质潮滩对波浪衰减的影响,在长江口崇明东滩南北两侧光滩,对潮滩波浪和底质特点展开了现场观测。结果表明:潮滩沉积物组成对波浪衰减有显著影响,淤泥质潮滩对波浪的衰减作用要大于粉砂质潮滩。水平方向上,淤泥质潮滩波能密度、平均波高和有效波高的衰减率分别为0.27%/m、0.12%/m、0.12%/m,粉砂质潮滩相应衰减率分别为0.18%/m、0.09%/m、0.08%/m,前者衰减率是后者的1.4倍;垂直方向上,淤泥质潮滩波能密度、平均波高和有效波高的衰减率分别为1.95%/cm、0.84%/cm、0.83%/cm,粉砂质潮滩相应衰减率分别为0.65%/cm、0.30%/cm、0.30%/cm,前者衰减率为后者的2.9倍。波浪高频部分的衰减率大于低频部分,相对波高值(平均波高/水深)越大,波浪衰减越强。

In order to investigate the wave attenuation on the tidal flat with particular sediment, the in situ ex- periments were conducted in Nov. 2010 on the northern and southern parts of Eastern Chongming Island, Yan- gtze Estuary, China. Based on the analysis of the surface sediment and wave parameters, the following results are concluded. （1） The wave attenuation on the muddy flat is greater than that on the silty flat. Along with the increase in distance and elevation, the wave attenuation ratio on the muddy flat is 1.4 and 2.9 times than that on the silty flat, respectively. （2） The relative wave height（average wave height/water depth） is 0.04 0.16, having positive linear relationship with wave attenuation. The muddy flat is better at wave attenuation with the same relative wave height. （3） Attenuation of wave with high frequency dominates when the wave is propagating landwards.