Abstract
Combined sewer overflows (CSOs) release pollutants collected in urban runoff into local waterways, impacting both aquatic life and human health. The impact of climate change on precipitation may result in an increase in the frequency and magnitude of heavy precipitation events, with a corresponding increase in CSO discharges. The installation of Green Infrastructure (GI) such as Porous Pavements (PP) is a resilient approach to mitigate CSO events. However, an understanding of the impact of climate change on CSO events and the effectiveness of GI practices is crucial for designing sustainable urban stormwater management systems. Using the Storm Water Management Model (SWMM), the performance of PP as a CSO abatement strategy was studied for the city of Buffalo, New York, USA. This paper used the Intensity-Duration-Frequency (IDF) curves for current (1970–1999) and future (2070–2099) design rainfall scenarios, with four rainfall durations (1, 6, 12, and 24 hours) and four return periods (2, 10, 50, and 100 years). The simulation results show that (1) current 100-year events generate CSO volumes similar to predicted 50-year events; (2) CSO volumes could increase by 11–73% in 2070–2099 compared to 1970–1999 when no GI intervention is performed; and (3) the installation of PP can reduce 2–31% of future CSO volume. This case study demonstrates the regional CSO challenges posed by climate change and supports the use of GI as a mitigation strategy.
Highlights
Land cover change from its natural state to impervious surfaces resulting from urbanization introduces an array of disturbances to the hydrological cycle (Saier, 2007)
The largest increase in combined sewer overflows (CSOs) volume magnitude corresponds to the 100-year return period and 24-h duration scenario
The results showed that while the CSO volume is linearly correlated with the magnitude of rainfall event, the relation is different among the periods of 1970– 1999 and 2070–2099 and varies with the duration and return period
Summary
Land cover change from its natural state to impervious surfaces resulting from urbanization introduces an array of disturbances to the hydrological cycle (Saier, 2007). Climate Change Impacts on CSOs stormwater and wastewater and expels excess untreated water volumes into nearby water bodies These discharges, known as combined sewer overflows (CSOs), transport washed-off atmospheric and urban surface pollutants along with the debris buildup in the CSS during dry weather periods and cause multiple adverse effects (e.g., WMO and GWP, 2008; Botturi et al, 2020). In the USA, the Environmental Protection Agency (EPA) provides guidance to municipalities on managing CSO discharges and complying with the National Pollutant Discharge Elimination System (NDPES) through a CSO Control Policy This CSO Control Policy details methods for handling discharge violations, including regular maintenance of the sewer system, prohibiting CSOs during dry weather, and requiring local long-term control plans (LTCPs). With control targets in place, the municipality must research alternatives for reducing the impact of CSOs to water quality and include climate change uncertainties in their LTCPs (NYSDEC, 2021)
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