Relationship Between Rainfall Duration and Sewer System Performance Measures Within the Context of Uncertainty

Bartosz Szeląg,Adam Kiczko,Grzegorz Łagód,Francesco De Paola

doi:10.1007/s11269-021-02998-x

Abstract

Urbanization and climate change have resulted in an increase in catchment runoff, often exceeding the designed capacity of sewer systems. The decision to modernize a sewer system should be based on appropriate criteria. In engineering practice, the above is commonly achieved using a hydrodynamic model of the catchment and the simulation of various rainfall events. The article presents a methodology to analyze the effect of rainfall characteristics parametrized with intensity-duration-frequency (IDF) curves in regard to performance measures of sewerage networks (flood volume per unit impervious surface and share of overfilled manholes in the sewerage network) accounting for the model uncertainty determined via the generalized likelihood uncertainty estimation (GLUE) method. An urban catchment was modeled with the Storm Water Management Model (SWMM). Analyses showed that the model uncertainty exerts a large impact on certain measures of sewage network operation. Therefore, these measures should be analyzed in similar studies. This is very important at the stage of decision making in regard to the modernization and sustainable development of catchments. It was found that among the model parameters, the Manning roughness coefficient of sewer channels yields a key impact on the specific flood volume, while the area of impervious surfaces yields the greatest impact on the share of overflowed manholes.

Highlights

Increasing urbanization and climate change have increased the diversion volume of stormwater from catchments, which has affected the water quality of receiving bodies and has resulted in more frequent sewer floods (Fletcher et al 2013; Karimlou et al 2020)
If a sewer system is to be modernized, it has been recommended to perform numerical modeling to formulate optimal decisions (Kolsky and Butler 2002; dos Santos Amorim et al 2020). This may be accomplished via numerous computer programs (e.g., MIKE and XPSWMM) implementing rainfall-runoff models of urban catchments (Kwak et al 2016; Yang et al 2020)
In the Storm Water Management Model (SWMM), a sewer flood is only represented in terms of the volume of sewage overflowing from sewer manholes during an analyzed event

Summary

Introduction

Increasing urbanization and climate change have increased the diversion volume of stormwater from catchments, which has affected the water quality of receiving bodies (river, lake or sea) and has resulted in more frequent sewer floods (Fletcher et al 2013; Karimlou et al 2020). If a sewer system is to be modernized, it has been recommended to perform numerical modeling to formulate optimal decisions (Kolsky and Butler 2002; dos Santos Amorim et al 2020) This may be accomplished via numerous computer programs (e.g., MIKE and XPSWMM) implementing rainfall-runoff models of urban catchments (Kwak et al 2016; Yang et al 2020). In addition to the properties of network channels, factors shaping surface runoff and sewer chamber conditions might be important. These issues play a major role in the correct determination of flow dynamics and in satisfactory model calibration. The flooding extent could be considered, but this could lead to much more complicated solutions requiring the definition of the link between the reservoir and sewer manholes (with weirs or orifices), which could cause numerical difficulties

Methods

Results

Conclusion