Xi'an Urban Rainwater Catchments Area Division And The The Research Of Runoff Characteristics Based On SWMM Model

In xi'an city area,with the rapid development of economy, xi'an urbanization increase year by year, lead to urban impervious area ratio is increased because of the rainfall runoff was greatly increased. At the same time urban storm the return period of continuous record in recent years by the impact of climate change and the urban heat island effect, lead to waterlogging disaster frequency has increased dramatically, xi 'an city waterlogging disaster happened almost every year in last decade. And fall behind rain flood waterlogging management system leads to waterlogging disaster degree more and more serious, urban waterlogging phenomenon has become one of the important factors which impact on urban residents live production and industrial and agricultural production. Therefore this article through to find a new method of rain flood management based on the rain flood control model to simulation study influencing factors of urban rainfall runoff and the law of runoff reduction,it is significance that provide theoretical reference for xi'an rainstorm waterlogging control.This paper divided xi'an urban area to several different rain flood management by xi 'an new drainage pipe network diagram and the geography data, based on SWMM model to simulate a certain management division which include a number of independent drainage unit is located under the pad surface rainfall runoff and factors. At the same time, based on the model simulation of different LID measures for the reduction law of runoff, and take runoff coefficient as the objective function to validate the parameters of the model. The main research results are as follows:(1) xi'an urban area is divided into 10 drainage management division according to the topographic data and xi 'an drainage pipe network information, almost no relationship between drainage partition.(2) The location of three adjacent independent drainage network systems is selected in the area of the moat river management area, Based on the present situation of SWMM model under the condition of simulation, it is concluded that the basin rainfall runoff characteristic value of flood peak, the actual, flood peak time and peak factor underlying surface runoff coefficient under the rain?the design rainfall return period and the influence law of underlying surface permeable rate.(3) After adding LID measures, simulation study area with the increase of LID measures layout area ratio and design rainfall return period increases, the actual LID measures for flood peak?flood volume and flood peak time underlaying surface runoff coefficient of cutting effect.With the increase of the area ratio of LID, the effect of the LID measure on runoff is linear;With the increase of the reproducing period of the design, the effect of the reduction of runoff was obviously decreased. The LID measures had the best effect on rain in low rainfall conduction,and as the rain increased, the effect of the sequestration decreased.