Study On Optimization Of Stormwater And Flood System In Small Town Based On SWMM

With the frequent occurrence of extreme rainfall in recent years,the urban rainwater facilities can not play their full role in coping with the rainstorm,and can not mitigate the damage caused by the rainstorm.In urban and rural planning,the traditional flood control engineering planning and rainwater flood engineering planning methods can not dynamically simulate the operation of the whole system in accordance with the conventional algorithm.In the face of the rapid development of urban flood disasters,the use of these methods has long been a bottleneck,it is urgent to more in line with the development of the times to solve the complex rainwater system problems.With the deepening of research,the application of storm flood management model(SWMM model)has gradually attracted people’s attention,and this method has also achieved good results in solving the problems of storm flood system.In this paper,Xixia District,zhenbeibu town of Yinchuan city as the typical arid areas.Firstly,the domestic and foreign research on rainwater model and drainage and waterlogging prevention is sorted out,and the composition of mathematical model and its application of rainwater drainage system are expounded.Secondly,the basic theory of SWMM model is discussed,and the basic method and operation steps of simulating rain-flood system by rain-flood model are expounded.According to the traditional design method,the design parameters are determined and the rain-flood pipeline network is planned and designed.Finally,based on the above research,the rainfall scenario is designed and the parameters of SWMM model are calibrated.Taking the small towns in arid areas as the research area,according to the current situation and future development,land use characteristics,topographic characteristics,the town of Zhenbeibu is divided into 68 catchment sub-regions.Then,a rainfall-flood system model is established in SWMM,and rainfall simulation is carried out under different rainfall recurrence periods.The problems of overload and overflow are optimized.The optimized pipe network system and the system with LID measures are simulated.It provides a reference for the design and optimization of rainwater system in small towns in arid areas.The main results of this study are as follows:(1)The development of rain-flood models at home and abroad was systematically sorted out,and the theoretical and practical knowledge of rain-flood models was learned and absorbed.On this basis,the optimization of rain-flood systems in small towns in arid regions was studied.Taking Xixia District,zhenbeibu town of Yinchuan city as the research object,the Chicago Rainfall Process Line Method was used to obtain the rainfall process lines under different rainfall recurrence periods.The whole system is divided into sub-regions and the network is generalized,and the parameters of the model are calibrated,and then the rain-flood system model in this area is established.(2)According to the four different recurrence periods of Rainstorm in one year,five years,20 years and 30 years,the simulation is carried out in batches and stages.The simulation results are as follows:11.43 m3/s,21.22 m3/s,33.09 m3/s and 36.55 m3/s,respectively.The time lag of peak runoff was 10-17 minutes,and the existence of flood currents was found.Pipe section and node of overflow problem.(3)After the adjustment of pipe network nodes and sections,the overload of the whole rainwater system is significantly reduced compared with that before the adjustment,and the overload of pipelines and canals is also significantly reduced.For the optimized rainwater-flood system,LID measures were added.It was found that compared with the absence of LID development control measures,the peak flow occurred 15 minutes later,and the peak flow reduction rate was 21.53%.The results show that the number of submerged nodes decreases from 6 to 4,and the duration of submerged nodes decreases by at least 34%.(4)Based on the above research,through SWMM model,we can see the rainwater problems in each catchment area,and also can analyze which drainage pipelines and drainage nodes have overloaded The simulation results under different rainfall scenarios can provide useful design and planning for urban rainwater system construction.With LID measures,it can effectively solve the problem of rain and flood in small towns in arid areas,and provide some theoretical and practical reference for future research.