Modeling of Municipal Drainage and Urban Channel Flooding in Coastal City in the South of China

Abstract

A numerical model has been formatted including ocean, rain drainage, urban channels, and pumps by the software MIKE FLOOD which coupling MIKE URBAN, MIKE 11 and MIKE 21. The different scenarios have been simulated. The flooding warning water level of the urban channel is low to the spring tide height, when the precipitation in 30 years facing the ocean tide in 5 years, the rain flooding in some areas should be stored in the urban channel, waiting for the ocean tide height decrease, then discharge the rain flood. Several conclusions have been drawn as followed: (1) In China, the average impervious surface in the urban area is usually about 55% to 70%, in the commercial central area, the impervious surface is usually about 75%-90%, the impervious surface in Beihai urban area is higher than the average level in China, because the density of the constructs is too high, the land use should be changed and the Sponge City should be constructed, these measures will help to release the urban flooding problem. (2) To carryout low impact development facilities and construct urban flooding storage, drainage system both very important in coastal area, especially in typhoon area. (3)Compare two pipe and channel plans, the results show that the water logging of initial plan was heavy, and the water logging of optimization plan is relieved.