Flow Simulation in Circular Pipes with Variable Roughness Using SWMM-EXTRAN Model

Abstract

The use of the Storm Water Management Model (SWMM) to simulate the runoff-transport phenomenon necessitates the proper calibration of the Manning roughness coefficient and the effect of variable roughness on the routed hydrograph attenuation and time to peak. The SWMM-EXTRAN program block (version 4) was adjusted to include the effect of variable Manning roughness for circular pipes. Real case studies show moderate improvement of the simulated hydrographs compared to the recorded hydrographs.