红树林生态系统中潮滩与植物消浪特性试验

Experimental study on wave attenuation characteristics of tidal flat and vegetation in mangrove ecosystem

采用室内水槽物理模型试验研究了潮滩、植物和红树林生态系统的消浪特性,量化了潮滩对红树林生态系统波高衰减的贡献。结果表明:随着植物淹没度的增大,潮滩、红树林生态系统的波高比均逐渐增大,即消浪效果越来越弱,而植物的波高比则是先减小再增大,水位在树冠中心时消浪率远高于其他植物部位;随着相对波高的增大,潮滩的波高比先稳定在1.0附近然后再减小,红树林生态系统的波高比逐渐减小,而植物的波高比先减小再增大;随着波长与植物带宽度的相对宽度增大,潮滩的波高比先略减小再增大,但多数稳定在1.0附近,而植物与红树林生态系统的波高比先增大再略微减小;潮滩对红树林生态系统波高衰减贡献随淹没度减小逐渐增大,最大可达63%;波浪在红树林生态系统传播过程呈非线性衰减,单位长度的波高衰减率在植物带前1/4宽度远大于后3/4宽度。

A physical model experiment was carried out in the laboratory flume to study the wave attenuation characteristics of tidal flat,vegetation and mangrove ecosystem,while the wave-height attenuation contribution of tidal flat to the mangrove ecosystem was quantitatively analyzed.The results show that with the increase of vegetation submergence,the wave height ratio of tidal flat and mangrove ecosystem increases gradually,namely the wave attenuation effect is getting weaker and weaker.The wave height ratio of vegetation first decreases and then increases,and the wave height ratio of vegetation is much higher than that of other vegetation parts when the water level is in the center of vegetation canopy.With the increase of relative wave height,the wave height ratio of tidal flat first stabilizes around 1.0 and then decreases,and the wave height ratio of mangrove ecosystem gradually decreases,while the wave height ratio of the vegetation first decreases and then increases.With the increase of relative width,the wave height ratio of tidal flat first decreases slightly and then increases,but most of them stabilize around 1.0,while the wave height ratio of vegetation and mangrove ecosystem first increases and then decreases slightly.The contribution of tidal flat to the wave height attenuation of mangrove ecosystem increases with the decreases of vegetation submergence,and the maximum contribution can reach 63%.Wave propagation in the mangrove ecosystem is characterized by the nonlinear attenuation and the attenuation rate of wave height per unit length is much larger in the first quarter width than that in the last three quarters width of the vegetation belt.