Study On Influence Of Submerged Plants On Flow And Sediment Re-suspension Characteristics

The submerged plants in river can effectively degrade the pollutants in water,prevent soil erosion, to beautify the environment, protect the banks. But the submergedplant changes the flow structure and sediment resuspension characteristics of its course,the river hydraulics problems become more complex. The predecessor to the flow andsediment characteristics of a submerged plant river is studied and achieved many results,but the natural submerged plant test research does not see more, it is necessary to makedeep research on the special and complex flow problems, research results to guidedevelopment of river ecological restoration and environmental protection etc. haveimportant realistic meaning.Based on the collection of relevant research on the flow property of plantscontaining River achievements at home and abroad, using natural submerged plantVallisneria spiralis series-simulation test carried out in the sink, and the use of theacoustic Doppler velocimeter (ADV) advanced in different conditions of flow parameterswere measured, using self-made micro disturbance siphon sampler the sample, usingturbidity instrument measuring flume on turbidity overlying water changes, made a lot ofvaluable first-hand data. Comparative analysis of the distribution characteristics, nonsubmerged plants and submerged plants containing water flow characteristics;comparative analysis of the effects of submerged plants in different planting patterns ofwater flow and sediment re suspension characteristics.Research results show that:(1) submerged plants changed flow velocity and turbulent planting area dynamiccharacteristics, reduce the river bottom shear stress; overlying water turbidity valuesshow that submerged plant test conditions can inhibit the river sediment resuspension.(2) the influence of transverse planting spacing on the flow characteristics, thesmaller distance, the near bottom velocity reduction effect more obvious, moreconducive to reducing the bottom of turbulence effect, inhibition of sediment resuspension; vertical planting spacing effects on the flow characteristics of less lateralspacing, but submerged plant cover water turbidity section still increase with longitudinalplanting spacing increases, which indicates that the longitudinal plant spacing also has certain effect on sediment resuspension.(3)With the increase of Froude number, before and after planting submergedplantdiversity increased velocity distribution curve;different Froude number conditions,turbulence intensity, turbulence kinetic energy maximum maximum value, the Reynoldsstress and the position of the maximum in the plant near the top; with the increase ofFroude number, planting density becomes greater, can significantly reduce the turbulencekinetic energy and shear stress at the bottom, the inhibiting effect on bottom sedimentresuspension significantly..