Runoff Simulation In The Urban Areas Of Taizhou Under Different Land Use Patterns

With global climate becoming warmer and the rapid development of urbanization, extreme climate and local short duration storm events in the city will occur more frequently. Domestic and foreign urban flood disaster events are outstanding, which seriously affect the traffic and cause great threats to people’s production life and even their life and property security. In order to realize effective management of urban storm water and enhance the ability of forecasting and warning urban rainstorm waterlog, this paper took the urban area of Taizhou city as the study area, SWMM model was introduced to research the influence on urban runoff and waterlog under different rainfall recurrence periods and rainfall styles. Main research results were summarized as follows:1、The related work about urban drainage and urban rainfall-runoff model at home and abroad was reviewed firstly, and then the general situation of Taizhou city’s urban area. According to rainstorm waterlog, related cause analysis was discussed. Finally, main problems of urban drainage system were summarized in this paper.2、The principle and application evaluation of the model was summarized. On the basis of surveying the terrain, pipelines trend and distribution, land use types and the ground slope, this paper conceptualizes the subcatchments and drainage pipe networks. Along with method and parameter optimization, Taizhou city’s SWMM model was established.3、The Chicago rain style formula and rainstorm intensity formula of Taizhou city were adopted to design the two-hour rainfall under the condition of different recurrence period (P=1,2,3,5,10,20) and different rain style(r=0.3,0.4,0.5). In addition, according to field survey, typical observed daily rainfall data of Taizhou hydrologic station was selected for simulation.4、The simulation results of SWMM model were analyzed. The runoff coefficient of each subcatchment, surface runoff, pipe load and pipe flow depth profile under the two-hour rainfall with different recurrence period and rainfall patterns were analyzed. The surface runoff, ponding area and node flow under observed daily rainfall of Taizhou hydrologic station were also analyzed.Research results showed that the SWMM model had a good applicability for Taizhou city’s urban area, which could be applied in rainwater pipe network planning, renovation, operation management and maintenance and provide technical and information support for the drainage system in this area. It had certain guiding significance both for the establishment of urban waterlog forecast and early warning system and urban flood prevention and mitigation.