Abstract: In the purpose of exploring the effect of vegetation roots on riverbank erosion process, the contribution rate of different vegetation roots to riverbank erosion protection was examined via indoor flume experiments. The undisturbed soil samples were taken from the banks of the Tarim River in Xinjiang, and the roots of local dominant shrubs Tamarix ramosissima and Populus arbores were selected as research objects. Results demonstrated that: (1) Rootless river bank mainly suffered from arc-shaped erosion with insufficient anti-scouring ability in the lower part, while rooted river bank mainly saw triangular erosion with strong anti-scouring ability in the lower part and good stability in the upper suspended layer. (2) The soil-fixing effect of the root system enhanced the impact resistance of river bank by 12%-42%. Given the root system of the same vegetation, the soil-fixing ability of the river bank differed remarkably with the arrangement of the root system: V-shaped root system had a superior soil-fixing effect than vertical system. Tamarix ramosissima root system had a better soil-fixing ability than Populus euphratica by 27% on average. (3) Root-soil cemented collapse body accumulated mainly in a triangular shape, and the proportion of accumulation is larger than that of non-rooted collapse; Tamarix ramosissima root cement collapse decomposed in a smallest rate. In addition, the root traction coefficient can be used to reflect the contribution of roots to riverbed protection, and can be estimated as 1.15~2.52 in calculation. The research findings offer theoretical basis for the slope protection of the Tarim River.

Key words: Tarim River, flume experiment, root network effect, root traction coefficient, river bank erosion