Development of a Computer Model of a Drainage System with Uncertainties in External Inflow and Channel Cross-section

Abstract

In urban development, stormwater drainage is an important aspect of infrastructure planning and design. Computer modeling has often been used to assist the design of the drainage system. With this type of modeling, external inflows to the system and channel configurations are important model inputs. As such, it is challenging to develop a model when there are uncertainties in external inflows and channel cross-sections. This paper presents the development of a computer model of a drainage system in Singapore. In the development, it is necessary to resolve the uncertainties in the external inflow at various points along the drainage system, as well as the uncertainties in channel cross- sections. The software package Stormwater Management Model (SWMM) was used and the model has been developed and calibrated with on-site measured data. The results show that the external inflows have significant effects on the simulated hydrographs, while channel cross-sections do not affect the simulated hydrographs. On the other hand, the channel cross-sections have significant effects on the simulated water levels in the drainage channels.