The Research On The Construction Way Of Sponge City Baeds On SWMM

The rapid development of society and economy had accelerated the process of urbanization.As the protection of ecological environment in the process of urban construction was ignored,the impermeable area of the underlying surface of the city was increased gradually,Thereby the natural state of the hydrological cycle process was changed.Some serious issues had also become increasingly prominent,such as the urban flooding,the water shortage,the waster of rainwater resources.And the water environment was deteriorated.Whose caused traditional drainage patterns was difficult to continue.Under this background,our country put forward the concept of sponge city.At present,the construction of sponge city was still in the primary stage.Regarding these issues above,the construction ways of sponge city were explorated and researched.First of all,the commonly stormwater models at home and abroad were compared,then SWMM model was selected as the simulation software and which composition,as well as theoretical basis were studied.In view of lacking of actual rainfall data in some parts of China,a model calibration method based on runoff coefficient was proposed in this paper,and further discussed the rationality of the method.Secondly,the theory system,the engineering measures,the adaptability and the control goal of the sponge city were introduced and analyzed.Coordinating with low impact development,conventional rainwater runoff storage and discharge system,super-conventional stormwater runoff storage and discharge system of the sponge city construction were emphasized,and its main facilities were highlighted.Based on the analysis of the main engineering facilities of each drainage system,various facilities were analyed and studied from the aspects of principle and function,design method and so on.Besides,the principles and methods of sponge city construction were explored,the decomposition of sponge urban control indicators in low impact development was studied intensively,and a three-level decomposition method of drainage based on sponge city special planning was proposed.Finally,on the basis of synthetically analyzing the general situation and suitability of the study area,the method of three level decomposition was used to decompose the control object in a construction division for special planning of Qingdao sponge city.The SWMM simulation software was used to build the rain flood model in drainage area 1.and the calibration method based on the runoff coefficient was used to further calibrate the model.By using the model,the system of rainwater runoff,the pipeline depth and the pollutant(SS,COD,TN,TP)emissions of the low impact development mode and the conventional urban development mode were simulated.The results indicated that the effect of the low-impact development facilities on the runoff was gradually reduced with the increase of the rainfall;the order of the effect of rainwater runoff control and pollutant reduction was residential area> public management area> commercial area.In addition,the improved triple bottom line of the analysis of the evaluation system was put forward,and the entropy weight method with strong objectivity as the method to determine the weight of index was adopted.