TR-41 : Development of dimensionless hydrographs for storm sewers using Kinematic wave routing techniques

Abstract

The study presents a methodology for the estimation of flood wave characteristics in rectangular sewers at a downstream location of a given inflow site using kinematic wave routing technique. For the development of dimensionless hydrographs and other relationship it is presumed that the flood wave would be contained within the sewer. Using the kinematic wave routing technique the dimensionless hydrographs are developed for rectangular sewers for different widths varying from 6 to 18 ft, different sewer slopes varying from 0.001 to 0. 009 and for different inflow hydrographs shapes. The relationship have been developed between sewer slopes and time lag of peak flow at downstream location of given site for different widths of sewer. These. relationship have been established for different shape of inflow hydrograph with peak flow varying from 100 to 500 cusecs. The relationship between peak flow and time lag of peak flow for given reach length corresponding to sewer, slope of 0.001 , and the relationship between sewer slopes, widths, peak flow and time lag of peak flow of routed hydrograph have also been established for different size of sewer for three different inflow hydrograph shapes. These relationships can be used for determining quickly the lag time of peak flow of outflow hydrograph at downstream site of the inlet point of channel, which may be useful for the economic design of size of Bola storm sewers.