Applying Similarity Theory In The Design Of A Laboratory Simulation System For Ecological Restoration Engineering In The Lake Littoral Zone

The lake littoral zone is a transitional zone between land and water,which is a natural barrier before the pollutant enters the lake,it plays a crucial role in the lake's management.This thesis studies the design of a laboratory system modelling the ecological restoration of the lake littoral zone.The similarity theory is applied to the design of the system,and the similarity criterions are obtained that need to be considered when modelling the real lake littoral zone.This thesis mainly considers the hydrodynamic and the physical and chemical processes including overland flow,solute transport,and sediment transport;the physical and chemical processes consisting of photochemical processes,nitrification,and denitrification processes,which occur in the lake littoral zone comprising the slight slope area and the shallow water area.In this thesis,we use the obtained similarity criterions to check whether the experimental design modelling sediment transport in the lake littoral zone from a previous author meets the necessary similarity conditions.The BANG1 D turbidity current flow model is used to simulate the experiment and to verify its similarity.The main conclusions from this thesis are listed as follows:(1)For the hydrodynamic processes in slight slope areas: the overland flow process needs to ensure that the model and the prototype are similar in rainfall,infiltration and gravity;the similarity criterion for the solute transport is the Peclect and exchange numbers;the sediment transport process requires that the model and the prototype are similar in the diffusion,the sediment source,rainfall,infiltration,detachment and entrainment.(2)The hydrodynamic processes in shallow water areas: the overland flow processes need to ensure the model and the prototype are similar in the sand carrying capacity,the shear force and the plant drag force;the solute transport process needs to ensure that the model and the prototype are similar in the diffusion and the interception of aquatic plants.(3)The Physicochemical processes in the lake littoral zone: The photolysis processes require that the model and the prototype are similar in the light attenuation and the light intensity;for the nitrification and denitrification processes,kinetic similarity must be valid in the simulation system.(4)In the case of application,five similarity criterions are obtained by the generalized equation of the sediment transport and adsorption process.The range of similarity criterions between the two is calculated by combining the actual field parameters and the existing experimental design parameters,and the magnitude of the five similarity criterions are compared.The results show that the magnitude of the similarity criterions of the two is different.It is shown that the existing experimental design does not meet the necessary similarity conditions.In the end,the experiment was simulated with BANG1 D turbidity model to verify the above conclusion.