This technical note presents results from flume experiments conducted in a straight prismatic asymmetric compound channel with two different floodplain roughnesses and rigid emergent vegetation along the floodplain edge in combination with a mobile and fixed main channel bed, respectively. It is found that the contribution of floodplain roughness and vegetation along the floodplain edge to the bulk friction factor is considerably reduced when studied in combination with a mobile main channel bed featuring bedforms. This in turn means that the effect of vegetation along the floodplain edge on the conveyance capacity and bulk friction factor may be overestimated if it is studied solely with fixed bed conditions. The presented results reveal the need to improve our understanding of the complex interplay between mobile beds and vegetation along the floodplain edge and its combined effect on compound channel conveyance capacity and hydraulics.

本技术说明介绍了在直棱柱形不对称复合河道中进行的水槽实验结果，该河道具有两种不同的洪泛区粗糙度和沿洪泛区边缘的刚性突水植被，分别与移动和固定的主河道床相结合。研究发现，当结合具有河床形态的移动主河床进行研究时，洪泛区粗糙度和沿洪泛区边缘的植被对整体摩擦系数的贡献显着降低。这反过来意味着，如果仅在固定河床条件下进行研究，沿洪泛区边缘的植被对输送能力和体积摩擦系数的影响可能会被高估。