Study On The Evolution Rule And Influence Mechanism Of Urban River

The particularity and complexity of the water cycle in urban areas is that it is strongly influenced by human activities.The natural water cycle path adds the inflow and outflow of water produced by human social systems,forming the natural-social dual water circulation system.In the past,the research on urban water ecology mainly focused on the process of the off-river hydrological cycle in the city circle.However,the study on urbanization on the complete system hydrological process inside and outside the city channel is relatively insufficient.In this study,a rapidly developing central city of the Central Plains—Zhengzhou City was selected as the research area,using model simulation methods,and centered on urban hydrological processes.The study was carried out from three aspects:urbanization process,extreme precipitation,and sponge city,to probe the characteristics of urban hydrological process under urbanization process.The main findings are as follows:(1)Based on the MIKE 11 and MIKE Urban platforms,using the topography,pipe network,water system,and river section data of Zhengzhou urban area,the coupled model of urban drainage and urban river flow dynamics in the research area was constructed,and the water depth distribution characteristics were analyzed during the precipitation process in small scale areas to determine the model parameters of the pipeline network.In addition,the measured runoff from the outflow section of Zhengzhou City of Jialu River was used to determine the coupling model parameters of urban drainage and urban river flow dynamics.Through the calibration of model parameters,the simulated value was in good agreement with the measured value.(2)Based on the changes in land use types and socio-economic factors under different levels of urbanization,the characteristics of urban hydrological response were simulated in the process of urbanization.The results show that with the increase of the level of urbanization,first of all,the influence of urbanization process on the runoff coefficient and peak of the urban pipe network system become larger,what’s more,the influence of urbanization process on the flood peak of the river during the flood season is significantly greater than that of the non-flood season,last but not least,the influence of urbanization process on the flood peak of the river during the flood season is much greater than that of the dry year.(3)Extreme precipitation events has a good response to urbanization.During the same recurrence period,with the increase of urbanization,the output of urban drainage network has increased significantly,the peak of pipe flow has been significantly earlier,the water accumulation time has been extended,and the flood peak of river runoff has been significantly earlier.The flood peak flow increased obviously,and with the increase of the recurrence period,its impact became more and more large.(4)By increasing the water penetration rate and rainwater accumulation utilization rate of the underlying surface and the capacity of the river to adjust and store,the pipeline outflow and river runoff have been significantly reduced,but the flow time of the pipe and the flood peak flow in the short period of heavy rain has been advanced.