The applicability of LID facilities as an adaptation strategy of urban CSOs management for climate change

Kyungmin Kim,Ryoungeun Kim,Jeonghyeon Choi,Sangdan Kim

doi:10.2166/ws.2021.285

Abstract

Abstract The magnitude and frequency of extreme rainfall due to climate change is increasing. Increasing rainfall causes serious hydrological problems in cities. Rainfall does not infiltrate the soil, but mostly flows through the sewer pipes into the stream. Most old urban watersheds have combined sewer pipes. When rainfall exceeds the capacity of the combined sewer pipes, sewage mixed with stormwater overflows the sewer pipes and flows directly into the stream. This is called Combined Sewer Overflows (CSOs). CSOs enter the stream with non-point source pollutants accumulated on the surface and pollute the stream. CSOs are one of the major water quality problems in older urban watersheds. This can be solved by replacing the combined sewer pipes with separated sewer pipes, but in reality it requires astronomical costs. As an alternative, the Low Impact Development (LID) technique has recently been introduced. In this study, we analyzed the effects of climate change on CSOs in urban watersheds and applied LID techniques to offset the effects. The LID facility was applied with the most commonly used Bio-Retention cells.

Highlights

Recent studies on climate change emphasize the severity of changes in future rainfall patterns (Christensen et al 2007; Sagarika et al 2016; Pathak et al 2017)
We investigated the effect of reducing combined sewer overflows (CSOs) by applying Bio-Retention (BR) among Low Impact Development (LID) facilities in Oncheon stream basin located in Busan, Korea
This study examined the extent to which the adverse effects of future climate change were offset when the project was applied to the Oncheon stream basin

Summary

Introduction

Recent studies on climate change emphasize the severity of changes in future rainfall patterns (Christensen et al 2007; Sagarika et al 2016; Pathak et al 2017). Increased rainfall causes serious hydrological problems in urban areas (Tamaddun et al 2016). Rainfall intensity is likely to increase even though rainfall due to climate change has decreased (Solmon & Coauthors 2007). When rainfall occurred in natural watersheds, rainfall infiltrated into the soil smoothly and did not generate much stormwater. Increasing impermeable area due to urbanization reduces rainfall infiltration and results in increased stormwater (Semadeni-Davies et al 2008). The peak flow increases and the time of concentration decreases, resulting in much stormwater in a short time (Anderson 1970). The magnitude and frequency of rainfall due to climate change are very likely to cause greater problems (Kharin et al 2007; Loo et al 2015; Burt et al 2016)

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Conclusion