Study On Design Standard Syntaxis Between Pipe Drainage And River Drainage Of Nanchang

In recent years, phenomenon of urban waterlogging caused by heavy rains occurs frequently in many cities. This have brought not only huge economic losses, but also a certain threat to urban safety, and it’s now getting worse. Significant greenhouse effect caused by urbanization leads to excessive rainfall intensity, Urban planning is irrational, historical reasons lead to low standards of stormwater piping design, the increase in impervious surfaces so that the runoff coefficient increases, river lakes and wetlands are severely damaged.These and other bad situations are the urban waterlogging worsening reasons.However, a more prominent issues emerged:during the heavy rainfall, urban roads store large number of water within the district, while the river and lake drainage pumping stations work less time because there is no water to pump away. Also there is a situation that there is no waterlogging on urban roads but in urban lakes, rivers and other water systems. This is the problem of design standard syntaxis between pipe drainage of the street, the community and river drainage of urban lakes.Pipe drainage is in the charge of the municipal department while river drainage is in the charge of water conservancy department. Both of their designs are,derived through the design storm, but the differences lie in rainstorm sampling mathed, designed rainfall duration, storage capacity, etc, which will lead to mismatching of the two design standards.This article is based on the rainstorm data of Nanchang. Annual multiple sampling method is used in pipe drainage design while annual maximum method is used in river drainage design. We can obtain the theoretic frequency curve of the two sampling methods respectively through curve-fitting method. And by frequency curve we can get the correspondence of return periods of the two sampling methods:When the return period of annual multiple sampling method is1year, corresponding one of annual maximum method is about1.7years; when the return period of annual multiple sampling method is2years, corresponding one of annual maximum method is about2.7years; when the return period of annual multiple sampling method is3 years, corresponding one of annual maximum method is about3.5years; when the return period of annual multiple sampling method is5years, corresponding one of annual maximum method is about5.2years; when the return period of annual multiple sampling method is10years, corresponding one of annual maximum method is about10.5years.This paper also describes the formula used in the pipeline drainage and river drainage design. Relatively speaking, it’s better to use the frequency curve which is calculated through rainfall data for the study of the design standard syntaxis.Based on design return periods of the two sampling methods, this paper take full consideration of the differences in the storage capacity of the pipeline and the river, use a different design duration. Eventually, we obtain the relationship of design standard syntaxis between pipe drainage and river drainage of Nanchang:When the pipe drainage design standard is1year, the river drainage design standard is about5years; when the pipe drainage design standard is2years, the river drainage design standard is5-15years; when the pipe drainage design standard is3years, the river drainage design standard is10-20years; when the pipe drainage design standard is5year, the river drainage design standard is20-35years.