Study On Similarity Law And Its Application In Urban And Watershed Rainfalls Simulation Experiment

Due to the global warming and the frequent occurrence of extreme rainstorm events,severe flood disasters have caused great losses to human society.Stormwater test is an important method for flood research.The establishment of stormwater test model can provide effective theoretical support for the analysis and research on the mechanism of rain flood damage,provide systematic data support for the validation of numerical model of rain flood,and provide technical support for flood disaster prevention and treatment.In this study summarizes the existing similarity theory system and all kinds of related river,dam,on the basis of model test research,based on the rainfall runoff process such as rainfall,runoff,infiltration of hydrodynamics principle,and put forward a set of suitable for city and river basin rain flood process similarity law of model test study,and deduces the similarity scale of hydraulic elements,It can be used as an effective tool for urban and watershed rainfall-runoff process test under the current situation,and can be used as a basis to optimize flood disaster management plan and analyze the relevant mechanism.The main research results are as follows:(1)Derivation of similar scale suitable for urban and watershed rainfall process model test.The similarity scale fully and completely considers the physical movement process of water flow and the effect of various forces in the process of rainfall generation and confluence,and studies and analyzes the action mechanism of various forces.According to the characteristics of water flow in the process of rainfall generation and confluence,the effect of some forces is ignored.The shallow water equation was used to characterize the rainfall and slope water movement process in urban and watershed,and the Reynolds equation was used to characterize the flow movement process in gully,and the corresponding similarity scale relationship was obtained through similarity transformation.The similarity scale makes up for the shortcomings of traditional rainfall model test,which only starts from the phenomenon similarity and cannot be extended to the analysis of prototype water flow mechanism,by complementation the research on the effect of various forces of water flow movement in the process of rainfall and runoff in cities and watershed,and achieves the goal of being effectively applied to the establishment of scaled rain flood model test.(2)Verify the similarity law of rain flood process simulation.Selection of city and watershed of shrinkage scale rain flooding simulation validated the accuracy of the calculation of similarity scale,the shrinkage scale of urban rain flood damage test model example,surface runoff process of 1:4 model test and prototype process were analyzed,the results showed that the trend of the shape of the surface runoff change curve,peak flow and peak time now,It is basically consistent with the prototype curve after scaling up.In the 1:100 scale numerical model of Fengxi New City in Xi Xian New Area,the simulation of rainfall and runoff process shows that the simulation process of scale scale is basically consistent with the actual rainfall process,and the errors of water depth and water area in typical waterlogging points are less than 15%with the measured results.In the 1:100 scale numerical model of Hulu River Basin,the errors are less than 10%by comparing the average of the measured flow and the average of the cross section flow.In the simulation of wangmaogou basin,the simulation results of water quantity,water depth and discharge of 1:100 scale model and prototype model are basically consistent,and the errors of water quantity and discharge are less than 1%.Through experiments and simulation of practical examples,it is revealed that the similarity scale established in this study has strong applicability to all kinds of terrain and underlying surface conditions,and the simulation effect is relatively good.(3)The application of similarity law in urban and watershed rainfall process simulation tests and practical regional simulation.To apply the similar scale in urban rain flood test model building basin,based on the experiment to simulate the sponge measures whether setting,different transverse and longitudinal slope degree of urban rain flood process,the influence of rainfall intensity and simulated rainfall and city transverse and longitudinal slope degree of permeable pavement infiltration rate,the result can be sponge for subsequent city urban construction and urban planning layout and provide some guidance.The similar scale derived in this study is suitable for the simulation experiment of urban and river basin rain flood process,and the experimental simulation research can be used to guide the actual city and river basin rain flood simulation,which has important theoretical basis and application value to support the rain flood simulation and flood disaster management.