Assessing combined sewer overflows with long lead time for better surface water management

Abstract

During high-intensity rainfall events, the capacity of combined sewer overflows (CSOs) can exceed resulting in discharge of untreated stormwater and wastewater directly into receiving rivers. These discharges can result in high concentrations of microbial pathogens, biochemical oxygen demand, suspended solids, and other pollutants in the receiving waters. The frequency and severity of the CSO discharge are strongly influenced by climatic factors governing the occurrence of urban stormwater runoff, particularly the amount and intensity of the rainfall. This study attempts to assess the impact of climate change (change in rainfall amount and frequency) on CSO under the high (A1FI) and low (B1) Special Report on Emissions Scenarios of the greenhouse concentration derived from three global circulation models in the north west of England at the end of the twenty-first century.

Keywords:

• combined sewer overflow
• climate change
• InfoWorks CS
• pollution risk
• time series

Acknowledgements

This paper is part of a research conducted at Liverpool John Moores University. Special thanks from the authors are due to MWH UK Ltd, United Utilities, Innovyse Ltd, and WRc for their support during the period of the research. The views expressed in the paper are those of the authors and not necessarily those of the collaborating bodies.