Study On The Attributes Of Sponge City In Liangqing District Of Nanning Based On SWMM

In the past 40 years of reform and opening up,China’s rapid economic development has leaped into the world’s second largest economy.However,the leap-forward development of the economy has accelerated the advancement of the urbanization process,and the quick-improving mode of production and construction has led to the frequent occurrence of “urban diseases”: population density,water resources shortage,flood and waterlogging,environmental pollution,poor water quality,and ecological deterioration.Emerged.The concept of urban construction development such as traditional "pollution first pollution control" and "rain storm flood drainage" has failed to comply with the requirements of sustainable development.Therefore,the concept of "sponge city" came into being,low-impact development and construction became eradicating "the urban area to see the sea".The sharp sword of the problem is also an inevitable choice for the country to strengthen the development goal of ecological construction.At present,China is setting off an upsurge in the construction of a sponge city,but the combination of real practice and theory is still in its infancy.This study first elaborate the practical significance of the implementation of the construction of the sponge city from both theoretical and practical aspects,summarizing the origin,development and research status of the concept of the sponge city at home and abroad,finally,conclude that the construction concept of the sponge city is highly compatible with the development status of the country and the necessity of building a sponge city in China.Secondly,the theoretical foundation,construction goals and major engineering measures of the sponge city are described.It is concluded that the construction of the sponge city must not only consider the concept of low-impact development and construction,but also take into account the actual conditions of the urban storage and drainage system and other infrastructure.The engineering measures for the construction of Sponge City are introduced in detail in terms of principles,functions,structure composition and design essentials,which provide a design basis for the construction of low-impact development models in the later period.Then,SWMM is selected as the simulation software of this study.The low-impact development model to be constructed is outlined from the aspects of principle,model composition and elements.In this study,a construction area in Liangqing District of Nanning City(hereinafter referred to as Liangqing District)is taken as the research area,and the control target(study area)is decomposed step by step to obtain multiple sub-water partitions to select the most representative water sinks.District 4 is the most simulated object.Before the simulation,parameter calibration of the catchment subarea four is performed to obtain parameters such as total annual runoff control rate and low impact development control index.The SWMM software is used to construct the rainwater flood model and the model parameters are calibrated using the comprehensive runoff coefficient method.Followed by the traditional development model,economic development model and the effect of the optimal development model for simulation analysis,the simulation results show that low-impact development measures for the surface runoff and irrigation canal flow control has a significant effect,while the rain peak flow There are also cuts and delays.Although the advantage of the optimal type in flow control gradually decreases with the increase of the return period of rainfall,in the traditional and economical development mode,when the irrigation canal flow reaches fullness,the optimal development model remains.It can significantly relieve the depth of flow in irrigation channels and the danger of flooding in irrigation channels.Finally,through the evaluation of the impact of low-impact development,the economical and optimal development models can all meet the construction requirements of the sponge city.At the same time,the impact of low-impact development measures on stormwater runoff control in residential areas,commercial areas,and public management areas under the design of rainfall is: residential area> public management area> commercial area.