Establishing formulas for design rainfall intensity estimation and contour maps of parameters of the formulas for the Northern Delta

Abstract

    In the design practice of urban storm water drainage systems, the design rainfall intensity formula or the rainfall intensity-duration-frequency relationship (IDF) is usually used in therational formula to estimate design flow rate of drainage sewers. The parameters of IDF relationship presented in the current drainage system design criterion of Vietnam (TCVN 7957-2008) were determined from rainfall data in years ago, so those need to be updated or renewed. This paper presents procedures and results of new IDF equations and contour map of parameters of the equations for the Northern Delta of Vietnam. Based on the contour maps, design engineers can determine design flow rate of sewers in ungauged areas.