考虑刚柔组合的海岸复合型植被消波特性研究

Research on wave dissipation characteristics of coastal composite vegetation considering rigid-flexible combination

海岸植被在消减波浪能量方面发挥着重要作用,植被消波是海岸生态防护的重要形式。以广州市南沙区龙穴岛北部近岸水动力特征为基础,通过波浪水槽物理模型试验探究不同淹没度、入射波高及柔性植被宽度比条件下单一型植被(柔性、刚性)和复合型植被(刚柔组合)消浪效果。研究结果表明:当淹没度α=0.67(低于树冠形心处淹没度0.03即水深略低于树冠形心)或α>1.00(水深高于树冠顶部)时,单一型刚性植被消浪效果最优;当淹没度α增大至0.78和0.83(分别高出树冠形心处淹没度0.08和0.13)时,柔性和刚性复合型植被消浪效果更好。随着波高的增大,单一型植被与复合型植被的消浪效果均增强。柔性植被宽度比值B/B_(0)对植被消浪系数K的影响与淹没度和波高有关:当α<1.00时,消浪系数K随B/B_(0)的增大先增大后减小;当α=1.00时,消浪系数K随B/B_(0)的增大先减小后增大再减小,且均在B/B_(0)时消浪系数达最大;当α>1.00时,消浪系数K随B/B_(0)的增大呈现减小的变化趋势。研究可为当地植被生态护岸工程建设提供理论支撑。

Coastal vegetation plays an important role in wave energy dissipation.Vegetation wave dissipation is an important form of coastal ecological protection.Based on the hydrodynamic characteristics of the nearshore area north of Longxue Island,Nansha District,Guangzhou City,this study investigates the wave dissipation effects of single-type vegetation(flexible,rigid)and composite vegetation(rigid-flexible combination)under different submergence degrees,incident wave heights,and width ratios of flexible vegetation through physical model experiments in a wave flume.The results show that when the submergence degree α=0.67(lower than the submergence degree at the crown center,which is 0.03,indicating that the water depth is slightly below the crown)or α>1.00(water depth higher than the top of the crown),the wave dissipation effect of single-type rigid vegetation is optimal.When the submergence degreeαincreases to 0.78 and 0.83(respectively,0.08 and 0.13 higher than the submergence degree at the crown center),the wave dissipation effect of flexible and rigid composite vegetation is better.With the increase of wave height,both singletype vegetation and composite vegetation show enhanced wave dissipation effects.The ratio of the width of flexible vegetation B/B_(0) affects the vegetation wave dissipation coefficient K,which is related to the submergence degree and wave height.When α<1.00,K increases first and then decreases with the increase of B/B_(0);when α=1.00,K decreases first and then increases,then decrease again with the increase of B/B_(0),and K reaches its maximum when B/B_(0)=0;when α>1.00,K shows a decreasing trend with the increase of B/B_(0).This study provides theoretical support for the construction of local vegetation ecological shoreline protection projects.