Analysis On Factors Of Urban Road Runoff Discharge And Control

The local flood could occure as the results of impervious underlying surface incresing, discorrect vertical road design, no critical design standard, poor management experience and so on during the urban road construction process. The situation of road local flooding in our country become worse and worse even some methods such as enlarge pipe diameter, detention facilities construction has been adapted. However, the effcet is very limited for the reasons of landuse lacking, comlicate underground condition and diffculties of construction. In this situation, the local runoff volume reducction, road surface detention and major drainage system proved to be a better philosophy to solve these problems by the success experience in the developed countries.The 2D-1D model is established in order to simulate the effect of retention facilities on local flood relief, local runoff volume reduction, peak flow reduction, peak flow delay as well as the influence of some factors on retention facilities effectiveness in this study. Two planes about road design with the consideration of Low Impact Development concept and major drainage system are also introduced in this study. The main research contents in this study include:(1) The effect of retention facility on peak flow reduction is very distinguished for the reduction effectiveness is between 74%~88%. Ths most important factor of retention facility is the distance of two gully followed by the road cross slope and the minimal influencial factor is road longitudinal slope. The peak flow delay time of each senarios varies from 2min to 13 min.(2) Less portion of road runoff volume could get into the retention facility as for the poor capacity of gully so more portion of the runoff is discharged by the road surface. The ability of retention has not be fully evaluated for the gully limit. Some methods could be adapted to optimize the detention facility.(3) Compared with other detention methods, the detention effect of road surface detention has lots of benefits, such as less landuse, low investments, less management requires, low construction cost and so on. The road surface detention also could improve the drainage standard, reduce the combined sewer overflow. The design of road surface alos should take the ground water level, topography, and urban local flood control plan into consideration. In addition, some road surface detention lane could be built in face of extreme storm and climate change.(4) The study introduces the main idea of major drainage system and some hydraulic caculation methods as well as road surface detention. At last, two cases is introduced which is designed with the consideration of Low Impact Development, road surface detention, major drainage systm.