Study On The Design Of Urban Flash Flood Prevention And Control Project Under The Concept Of Sponge City

Along with the advancement of urbanization,almost all major cities are expanding.The mountains that originally belonged to the suburbs and rural areas have been included in the city,and the surrounding areas of the mountains,such as farmland,which can be used as flood discharge areas,are constantly being transformed into cement floors.The impermeable underlying surface causes the leakage of mountain runoff during the flood season to increase the risk of waterlogging in the downhill urban area,endangering the lives and property safety of residents in the urban area.The traditional concept of mountain flood prevention and control can no longer meet the needs of flood control and drainage around the mountain in cities.The concept of sponge city provides a new idea for the design of mountain flood prevention and control projects.Under the sponge city concept,four aspects of the transformation of urban mountain torrent prevention and control engineering design have been systematically summarized,namely: the transition from early warning and accelerated discharge to the combination of discharge and storage,from the protection of key targets to the protection of the overall system,and from The transition from concentrated rainwater discharge to the combination of centralized and scattered discharge,from water safety to water safety,water environment,and water ecology;in-depth analysis of sponge-type permeable dams,sponge-type storage dams,storage ponds and sponges The main points of the design of the type water and soil erosion prevention and control plan,The corresponding design principles and design methods are put forward,and the applicability,construction difficulty,and economy of various measures are comprehensively discussed,which provides technical guidance for the design of urban mountain flood prevention and control projects under the concept of sponge city.Taking the south slope of Zijin Mountain in Nanjing as the research object,a hydraulic model combining drainage and storage has been constructed.Simulation analysis shows that in the case of two-hour rainfall in 5 and 50 years,the sponge-type water storage dam and water storage are jointly used.Sponge prevention measures such as ponds can effectively reduce the peak flow by 40% to 61%.According to the calculation results of the model,detailed engineering design was carried out,and the Zijin Mountain torrent prevention and control project was implemented in 2017.In 2018 and 2019,several heavy rainfall events above100 mm showed that,Sponge-type flash flood prevention and control measures have improved the ability to respond to flash flood disasters,and fundamentally solved the hidden flood disasters in the Youyi River Basin under the Zijin Mountain.