| According to the implementation plan of the major water special sub-project "study on hydrological hydrodynamic characteristics and optimization technology of estuaries" provided by the entrusting party,the main research content of this project is to analyze the impact of hydrological hydrodynamic conditions on ecological environment in the research area through physical model tests.Through field investigation to determine the ecological restoration area hydrodynamic conditions and aquatic vegetation types,with a water plants,floating leaf plants,floating plant and submerged plant in selecting typical representative,the in-situ measurements,collect the estuary hydrologic data of different types of aquatic plants,the hydrodynamic conditions change on the estuary in the early planting main factors that influence the normal growth of aquatic plants,identification of the hydrodynamic factors that affects the river habitat conditions;The hydrologic and hydrodynamic optimization technology for the estuary area shall be researched and developed,with emphasis on the research and development and application of multi-functional ecological flexible diversion technology for the outer section of the estuary.Through data collection and site survey,selecting reasonable scale and combining physical model test with field observation,the optimization test of ecological flexible diversion dam in meiliang estuary under hydrologic and hydrodynamic conditions was carried out,and some Suggestions were put forward for the optimization measures to be implemented in the local estuary.The main contents of the paper include:(1)The diversion dam model changes the vertical distribution structure of the flow velocity.The horizontal and longitudinal flow velocity on the section increases with the increase of the flow rate,and the change rule basically tends to linear growth.The horizontal and longitudinal velocity on each vertical line is affected by the flow rate and increases with the increase of the flow rate,but the flow rate structure is less affected by the flow rate.In the non-model channel,the flow rate has little influence on the turbulence intensity distribution,and there is no obvious difference in the turbulence intensity distribution along the river width direction,but the turbulence intensity distribution along the water depth direction is consistent:in the same section,the turbulence intensity under different single wide flow rate shows a trend of first increasing and then decreasing from the bed surface to the water surface.When the flow rate is large,the turbulent region tends to move downstream with the increase of the flow rate.In conclusion,the turbulence intensity is caused by two factors:one is the resistance of the diversion dam,the other is the flow rate.(2)Relative submergence degree,Angle of supporting dam and Angle of main dam all have significant influence on vertical structure of horizontal longitudinal velocity on the section.According to the influence of the ecological flexible diversion dam on the vertical distribution of water flow under different submergence degrees,it can provide a theoretical reference for formulating the implementation plans for protecting different types of aquatic vegetation.With the increase of water depth,the proportion of the actual flow of the diversion dam decreases,and the intensity of three-dimensional turbulence on the vertical lines of the cross section mainly shows a trend of increasing from the bed surface to the water surface.(3)Using the reduction rate for parameters describing the ecological flexible diversion dam on water flow movement slowing effect,further from the perspective of water energy analysis the ecological flexible impact on energy dissipation characteristics of the water diversion dam,and compared the different discharge per unit width,different submergence degree,different Angle of the dam and the main point of view under the influence of the different levels on the vertical section of longitudinal velocity reduction rate.It can be seen that the reduction rate is mainly concentrated around 0.5,indicating that the deceleration effect is better under the influence of model arrangement,water level and various flow combinations When water flows to the downstream section behind the dam,the flow field is basically stable(4)Distribution law of rate reduction near the surface of water under these two submersion degrees(water depth 0.55 m and water depth 0.45 m).In the final section measured downstream behind the dam,the rate reduction under the influence of model arrangement A showed A trend of gradual decrease from the left wall to the right wall.Under the influence of model arrangement B,the rate of decrease from the left wall to the right wall showed a trend of first increasing and then decreasing.Under the influence of model alignment C,the decreasing rate from the left wall to the right wall showed a trend of increasing gradually.(5)When comparing the influence of different branch dam angles on water flowing to the final section measured downstream behind the dam,although there are differences in the deceleration effect of the vertical section under the influence of various permutation of the model,there is little difference in the deceleration effect of the permutation mode.This is mainly because when water flows to the final section measured at the downstream of the dam,the flow field is basically a problem.The variation of the Angle of the branch dam has little difference in the deceleration effect of each vertical line of the section,while the good deceleration effect of the section is mainly due to the joint action of the Angle of the branch dam and the turbulence vortex near the dam.The energy dissipation rate near the right bank increases with the decrease of the Angle of the supporting dam.(6)By comparing the influence of different main dam angles,it is found that when water flows to the final section measured downstream behind the dam,the reduction rate of each arrangement of the model on the vertical line shows a significant difference,among which arrangement D has the best deceleration effect,and the positions with the best deceleration effect are the left bank and the right bank.Under the influence of each arrangement,the wall position of the left and right sides of the energy dissipation rate is the largest,and the middle position is relatively small. |
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