Abstract: Ecological sandless concrete has been widely used in artificial ecological river bank protection project due to its exceptional properties, such as robust water and air permeability, as well as its ability to connect the water and land ecosystems. Ecological sandless concrete should not only meet the stability requirements of river bank slope, but also have the capacity to withstand erosion for vegetation growth. This study aims to elucidate the mechanism and effectiveness of backwater and flow velocity reduction offered by plants on ecological sandless concrete banks. To achieve this objective, a series of indoor scouring experiments were conducted under controlled varying flow velocities. The impact of different plant species growing on the ecological sandless concrete bank on water levels and flow velocities was examined. The findings demonstrate that cynodon dactylon exhibits superior backwater effects compared to manila grass, primarily due to its greater height and reduced susceptibility to falling. Conversely, manila grass demonstrates better performance in mitigating water velocity than cynodon dactylon, owing to the influence of plant density on the intensity of flow turbulence. Moreover, the reduction in velocity was more evident in sections closer to the plant layer, with a maximum reduction rate of 75.24%. Notably, both manila grass and cynodon dactylon were capable of withstanding water flow velocity of 5 m/s. This study provides valuable insights for enhancing construction techniques and selecting suitable plant species when utilizing ecological sandless concrete for riverbank slope stabilization.

Key words: ecological bank protection, ecological sandless concrete, cynodon dactylon, manila grass, anti-scouring performance