摘要
为研究风浪作用下水生植物对水流结构的影响,选取太湖中两种典型沉水植物(苦草与马来眼子菜)为研究对象,分别对苦草植物斑块与马来眼子菜植物斑块内外水体的瞬时流速进行野外现场测量,利用瞬时流速的能量谱分布将波浪流速与紊动流速分离,分别分析水生植物对时均流速、波浪流速以及紊动能的影响。风浪影响下,水体中存在流向与测量时近水面处盛行风向一致的水流;波浪流速以垂向流速为主,且波浪流速自水面向床底逐渐减小;紊动能在水面处达到最大值,并向床底方向逐渐减小。与无植被条件相比,苦草与马来眼子菜的存在减小了时均流速、波浪流速以及紊动能。两种植物形态上的差异,导致其对水流结构的影响不同:苦草叶片阻流面积在冠层中部达到最大,使得时均流速与波浪流速在苦草中部位置的减小程度最大;马来眼子菜叶片主要集中于冠层顶部(水面附近),其对时均流速以及波浪流速的减小作用在水面处达到最大。
To study the influence of aquatic vegetation on flow structure under wind-driven waves,field experiments were conducted with two types of typical submerged vegetation(i.e.,Vallisneria natans and Potamogeton malaianus) in Lake Taihu in China by measuring flow velocity inside and outside the vegetation patches. By decomposing the wave velocity and turbulent velocity from the spectra of the instantaneous velocity,the influence of vegetation on the distributions of time-averaged velocity,wave velocity and turbulent kinetic energy(ETK) was analyzed in this paper. For each case,a current in a direction consistent with the direction of near-surface wind occurred. The wave velocity was dominated by the vertical component and decreased from water surface to bed bottom. ETK reached its maximum near the water surface and decreased toward the bed bottom. Compared with bare bed,the presence of Vallisneria natans and Potamogeton malaianus decreased the time-averaged velocity,wave velocity,and ETK,and the differences in morphology between these two types of vegetation led to discrepancies in flow alteration. For Vallisneria natans,the canopy frontal area reached a maximum at the middle reach of plant,making the decrease of time-averaged and wave velocities largest near the middle of canopy. With blades concentrated at the top of canopy,the reduction in the time-averaged and wave velocities caused by Potamogeton malaianus was largest near the water surface.
作者
张英豪
赖锡军
张琳
姚昕
邓焕广
ZHANG Yinghao;LAI Xijun;ZHANG Lin;YAO Xin;DENG Huanguang(School of Environment and Planning,Liaocheng University,Liaocheng 252000,China;Key Laboratory of Watershed Geographic Sciences,Nanjing Institute of Geography&Limnology,Chinese Academy of Science,Nanjing 210008,China)
出处
《水科学进展》
EI
CAS
CSCD
北大核心
2020年第3期441-449,共9页
Advances in Water Science
基金
国家自然科学基金资助项目(41901120)
中国科学院战略性先导科技专项(A类)资助项目(XDA230402)。
关键词
水生植物
时均流速
紊动能
风浪
太湖
aquatic vegetation
time-averaged velocity
turbulent kinetic energy
wind waves
Lake Taihu
