| The acceleration of urbanization has changed the hydrological mechanism of the urban underlying surface,resulting in frequent occurrence of waterlogging in urban areas.For the purpose of prevent the occurrence of urban waterlogging and enhance the city's safety and flood prevention capabilities,our country become paying more and more attention to urban flood control planning and designing,as well as promoting the construction of sponge cities,actively.As the first batch of sponge cities in the country,Gui'an New District plays a crucial role in the economic development of the Southwest.This paper takes Gui'an New Area Demonstration Zone as the research object,based on the hydrogeological conditions,underlying surface conditions of the demonstration area of Gui'an New District and the rainfall runoff related data of the research area,combined with the spatial data and urban pipe network data of the demonstration area of Gui'an New Area for reasonable generalization.Constructed an urban storm flood model in the demonstration region of research area based on SWMM model,and stormwater measures such as concave-down green space,permeable pavement and green roof to the pre-planning,post-planning and post-planning were added to the demonstration region.The flood measures carried out scenario research and simulated analysis under the conditions of measured rainfall and designed rainfall,designing the demonstration area before and after the planning,single rain flood measures and combined rain flood measures and other scenarios to optimize the different scenarios.The main research contents and results are as follows:(1)According to the collected rainfall runoff data of meteorological stations and hydrological stations near Gui'an New District,the hydrological statistics method was used to analyze the rainfall runoff process and the rainstorm frequency in Gui'an New District,and the storms,rainfall runoff changes and runoff in Gui'an New District were determined.The coefficient changes regularly.(2)Based on the underlying surface conditions and the pipe network data of the demonstration area of Gui'an New District,the storm flood model before and after the planning of the demonstration area and the model which contains rainstorm measures will be setted up.After the planning of the demonstration area of Gui'an New District,the surface type will be changed due to the type of underlying surface.The surface impervious area increased,the surface runoff increased,the flood peak time was advanced,and the peak flow also increased.(3)According to the relevant prescript of sponge city construction in Gui'an New District,coupled with the characteristics of the underlying surface of the study area,under the conditions of measured rainfall and designed rainfall,design seven stormwater measures combination scenarios of stormwater measures were designed to simulate and analyze the study area,and assess the effects of different stormwater measures combinations on stormwater control.(4)To some extent,whether in the measured rainfall process or in the design of rainfall process,stormwater measures such as concave-down green space,green roof and permeable pavement can intercept and save runoff,reduce flood peak flow and delay flood peak occurrence.Meanwhile,there are some differences in the hydrological effects of these three measures under different rainfall conditions.(5)By setting up different stormwater management measures in Gui'an New District and carrying out simulation analysis,the results show that reasonable combination of stormwater measures can not only effectively reduce the flood peak flow and total runoff in the study area and increase the infiltration,it also can minimize the cost of sponge city construction.From the comprehensive analysis of the hydrological effect and economic cost of the stormwater control effect,it can be drawn that the optimal urban stormwater management measures in the demonstration area of Gui'an New District are “concave-down green space+ permeable pavement”,which can provide effective technical support for the construction of sponge city and rainwater resources in Gui'an New District. |
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