为研究边坡植被对河道行洪的影响，开展室内物理模型试验，测试典型流量下边坡无植被、稀疏植被、稀疏 植被+乔灌木和密集植被 4 种情形对应的水面线，并根据原模型相似率反演试验工况对应的原型参数和水位差。 结合经典的综合糙率计算公式进行数理分析，构建边坡由无植被改为栽种植被引起综合糙率增加的计算公式，提 出分析边坡植被影响河道行洪的实用方法。结果表明：综合糙率增加值与栽种植被区域湿周占总湿周的比值、栽 种植被区域糙率值 2 个因素有关，随栽种植被糙率值的增加而增加，随河道宽深比的增加而减小；当河道宽深比 大于 60 时，边坡栽种植被引起的综合糙率增加不超过 10%；当河道宽深比大于 100 时，边坡裁种植被引起的综合 糙率增加不超过 7%。上述研究成果为边坡栽种植被河道的行洪设计与运行管理提供一定的参考。

Urban river channel is an important element in city economy and ecology development. Considering soil and water conservation, landscaping or ecological factors, the river bank is usually planted with grass, shrub and other vegetation. The plant coverage has changed the flow surface of the river bank, as well as the flood discharge capacity. Flood control and management is the most crucial factor for the planning of urban rivers, thus, it is quite necessary to study the influence of bank vegetation on river flood discharge.In order to analyze the effect of bank vegetation on river flood discharge, physical model experiments were carried out in laboratory. An experimental platform was built with the length of 40 m, the width of 8 to 12 m, the water depth of 4 to 8 cm and the width depth ratio of 100 to 300. The water levels of no vegetation, sparse vegetation, sparse vegetation + shrub and dense vegetation, were tested under typical flow. Then, the prototype parameters and water level difference corresponding to the tested conditions, were deduced according to the similarity principle. Mathematical analysis was further conducted on basis of the classical composite roughness calculation formulas, including Pavlovskij formula and Einstein-Banks formula. An equation was proposed to determine the increase of composite roughness while the river bank changed from no vegetation state to planted vegetation state. A practical procedure was also given to analyze the influence of bank vegetation on river flood discharge.The results showed that, the water level of the tested channel increased by 0.3 to 1.3 mm due to the dense vegetation, while it increased by 0.1 to 0.4 mm due to the sparse vegetation and sparse vegetation + shrub. The denser the bank vegetation, the higher the water level. For a river with the length of 400 m, the water depth of 0.4 to 0.8 m, and the roughness of 0.026, the water level increased by 2 to 15 mm. For a river with the length of 2200 m, the water depth of 2.2 to 4.4 m, and the roughness of 0.035, the water level increase could be large as 70 mm. When the river bank planted vegetation, the increase of composite roughness was related to two factors, namely, the ratio of the covered wetted perimeter to the total wetted perimeter and the roughness of the covered area. It increased with the growth of the roughness of the vegetation covered area, and decreased with the increase of width-depth ratio. While the width-depth ratio was larger than 60 and 100, the growth of composite roughness due to planted vegetation was no more than 10% and 7%, respectively.Urban river bank is usually planted with grass, shrub, or other vegetation, and the water level increases with the growth of the vegetation density. The water level growth can be large as 70 mm in the river length of 2200 m. The water level increase should be given special consideration. The composite roughness increase is related to the ratio of the planted wetted perimeter to the total and the roughness of the planted area. For the river whose width-depth ratio is larger than 100, the increase of composite roughness is no more than 7%. The formula was proposed to calculate the variation of composite roughness while the river bank vegetation changed. Further, an analysis procedure was given to guide further design.