| The sea buckthorn flexible dam is a kind of new biological measure which can effectively confine sediment in gully channel and suppress soil erosion in gully bed in the soft rock region. A filed experiment on the effects of sea buckthorn plant flexible dam on constant water flow test both with and without sediment was conducted in Mei country in Shaanxi province. Based on the experimental data, first of all, the effects of water resistance in the sea buckthorn flexible dam test bed witch cross section is trapezoidal are analyzed. The influence of the sea buckthorn flexible dam on water flow characteristics under the different planting parameters are discussed, mainly including water depth and velocity changes in the longitudinal and lateral direction in the sea buckthorn flexible dam. The second, the variation of water sediment concentration of sands contained flow in the flow direction on each test bed and the distribution of sediment particle size under the influence of sea buckthorn plant flexible dam are analyzed. Finally, according to the on-the-spot investigation of typical soft rock region in Inner Mongolia——East-one-Branch gully of Xi-Zhao ditch,Zhungeer County and relevant data collecting, the VFSMOD model was used. The model was used to simulate the reduction of overland flow and sediment interception effect of sands contained flow under the influence of Sea buckthorn-herbs compound vegetation zone of East-one-Branch Small watershed. According to the results of the simulation, Related design parameters of Sea buckthorn-herbs compound vegetation zone are discussed in this paper.The main achievements as follows:(1) Test research shows that the sediment interception capacity of the sea buckthorn flexible dam depends on planting design parameters of the sea buckthorn flexible dam, and also determined by the growing status of the sea buckthorn plant flexible dam. The length of the flexible dam, cropping pattern, planting density and other planting parameters have certain influence on the flow velocity, the length of the dam is the main influence factors among them.(2) flow velocity of the vertical distribution in test bed was affected by sea buckthorn growing situation、the distribution of branch, stem and leaf of sea buckthorn shrubs and the arrangement of sea buckthorn line etc. major changes have taken place in the distribution of flow velocity along the vertical direction, and it changes present "S" type. The maximum flow rate occurs below the surface of the water about 0.6 times that of water deep.(3) The overall trend of sediment concentration of sea buckthorn flexible dam in different sections under different slope and different planting parameters is declined along the flow. Only when the dam is moderate, sorting sand effect is the best. But with a steeper slope, sand effect instead reduced. The sediment concentration in the Sea buckthorn flexible dam has a certain regularity. Sediment concentration is gradually reduce in upstream of dam body position, increased in the dam center and gradually reduce in the downstream dam.(4) sediment particle size showed a trend of decline in the sea buckthorn flexible dam, and the particle size of sediment have separation effect is greater than 2.5 um, shows that it has on the thick line of fine, the function of the natural separation of sediment.(5) VFSMOD model is applied to simulate the inflow and sediment interception and reduction effect of sea buckthorn-herbs mixed vegetation zone, found that different ways of sea buckthorn-herbs configuration has a great influence on interception effect of inflow and sediment. |
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