Analysing urban floods and combined sewer overflows in a changing climate

2011 ◽  
Vol 2 (4) ◽  
pp. 260-271 ◽  
Author(s):  
V. Nilsen ◽  
J. A. Lier ◽  
J. T. Bjerkholt ◽  
O. G. Lindholm
Keyword(s):  
Climate Change ◽  
Time Series ◽  
Urban Areas ◽  
Convective Precipitation ◽  
Urban Drainage ◽  
Combined Sewer Overflows ◽  
Extreme Precipitation Events ◽  
Combined Sewer ◽  
Sewer Overflows ◽  
Precipitation Events

Climate change is expected to lead to an increased frequency and intensity of extreme precipitation events. For urban drainage, the primary adverse effects are more frequent and severe sewer overloading and flooding in urban areas, and higher discharges through combined sewer overflows (CSO). For assessing the possible effects of climate change, urban drainage models are run with climate-change-adjusted input data. However, current climate models are run on a spatial–temporal scale that is too coarse to resolve processes relevant to urban drainage modelling, in particular convective precipitation events. In the work reported here the delta-change method was used to develop a high-resolution time series of precipitation for the period 2071–2100 based on a recently produced climate model precipitation time series for Oslo. The present and future performance of the sewer networks was determined using MOUSE software. The simulations indicated future increases in annual CSO discharge of 33% when comparing years of maximum annual runoff. There is also an 83% increase in annual CSO discharge when comparing years of maximum annual precipitation. In addition, there are increases in the flooding of manholes and increased levels of backwater in pipes, which translates into more flooding of basements.

The effect of climate change on urban drainage: an evaluation based on regional climate model simulations

2006 ◽  
Vol 54 (6-7) ◽  
pp. 9-15 ◽  
Author(s):  
M. Grum ◽  
A.T. Jørgensen ◽  
R.M. Johansen ◽  
J.J. Linde
Keyword(s):  
Climate Change ◽  
Extreme Precipitation ◽  
Climate Model ◽  
Regional Climate ◽  
Rain Gauge ◽  
Urban Drainage ◽  
Extreme Precipitation Events ◽  
Rainfall Extremes ◽  
The Future ◽  
Precipitation Events

That we are in a period of extraordinary rates of climate change is today evident. These climate changes are likely to impact local weather conditions with direct impacts on precipitation patterns and urban drainage. In recent years several studies have focused on revealing the nature, extent and consequences of climate change on urban drainage and urban runoff pollution issues. This study uses predictions from a regional climate model to look at the effects of climate change on extreme precipitation events. Results are presented in terms of point rainfall extremes. The analysis involves three steps: Firstly, hourly rainfall intensities from 16 point rain gauges are averaged to create a rain gauge equivalent intensity for a 25 × 25 km square corresponding to one grid cell in the climate model. Secondly, the differences between present and future in the climate model is used to project the hourly extreme statistics of the rain gauge surface into the future. Thirdly, the future extremes of the square surface area are downscaled to give point rainfall extremes of the future. The results and conclusions rely heavily on the regional model's suitability in describing extremes at time-scales relevant to urban drainage. However, in spite of these uncertainties, and others raised in the discussion, the tendency is clear: extreme precipitation events effecting urban drainage and causing flooding will become more frequent as a result of climate change.

scholarly journals Socio-Economic Assessment of Green Infrastructure for Climate Change Adaptation in the Context of Urban Drainage Planning

2020 ◽  
Vol 12 (9) ◽  
pp. 3792 ◽  
Author(s):  
Luca Locatelli ◽  
Maria Guerrero ◽  
Beniamino Russo ◽  
Eduardo Martínez-Gomariz ◽  
David Sunyer ◽  
...  
Keyword(s):  
Decision Making ◽  
Green Infrastructure ◽  
Waste Water Treatment ◽  
Economic Assessment ◽  
Environmental Benefits ◽  
Urban Drainage ◽  
Combined Sewer Overflows ◽  
Damage Reduction ◽  
Combined Sewer ◽  
Sewer Overflows

Green infrastructure (GI) contributes to improve urban drainage and also has other societal and environmental benefits that grey infrastructure usually does not have. Economic assessment for urban drainage planning and decision making often focuses on flood criteria. This study presents an economic assessment of GI based on a conventional cost-benefit analysis (CBA) that includes several benefits related to urban drainage (floods, combined sewer overflows and waste water treatment), environmental impacts (receiving water bodies) and additional societal and environmental benefits associated with GI (air quality improvements, aesthetic values, etc.). Benefits from flood damage reduction are monetized based on the widely used concept of Expected Annual Damage (EAD) that was calculated using a 1D/2D urban drainage model together with design storms and a damage model based on tailored flood depth–damage curves. Benefits from Combined Sewer Overflows (CSO) damage reduction were monetized using a 1D urban drainage model with continuous rainfall simulations and prices per cubic meter of spilled combined sewage water estimated from literature; other societal benefits were estimated using unit prices also estimated from literature. This economic assessment was applied to two different case studies: the Spanish cities of Barcelona and Badalona. The results are useful for decision making and also underline the relevancy of including not only flood damages in CBA of GI.

scholarly journals Exploring the performances of a new integrated approach of grey, green and blue infrastructures for combined sewer overflows remediation in high-density urban areas

2018 ◽  
Vol 49 (4) ◽  
pp. 233-241 ◽  
Author(s):  
Daniele Masseroni ◽  
Giulia Ercolani ◽  
Enrico Antonio Chiaradia ◽  
Marco Maglionico ◽  
Attilio Toscano ◽  
...  
Keyword(s):  
Urban Areas ◽  
Oxygen Demand ◽  
Integrated Approach ◽  
Integrated System ◽  
Limiting Factor ◽  
Combined Sewer Overflows ◽  
Economic Point ◽  
Modelling Framework ◽  
Combined Sewer ◽  
Sewer Overflows

Most sewage collection systems designed between 19th and early to mid-20th century use single-pipe systems that collect both sewage and urban runoff from streets, roofs and other impervious surfaces. This type of collection system is referred to as a combined sewer system. During storms, the flow capacity of the sewers may be exceeded and the overflow discharged into a receiving water body (RWB) through spillways without any control and remediation. Combined sewer overflows (CSOs) may, therefore, produce serious water pollution and flooding problems in downstream RWBs. Methodologies for a rational management of CSOs quantity and quality share many commonalities, and these two aspects should be considered together in order to maximize benefits and promote local distributed actions, especially in high urban density areas where the space availability for the construction of CSO storage tanks is often a limiting factor. In this paper, a novel strategy to control downstream flow propagation of a CSO as well as to improve its quality is tested on a real case study in the area of the metropolitan city of Milan. The approach is based on the combination of grey, green and blue infrastructures and exploits the integrated storage and self-depuration capacities of a firstflush tank, a constructed wetland and a natural stream to obtain admissible flow rates and adequate water quality in the RWB. The results, evaluated through a modelling framework based on simplified equations of water and pollutants dynamics, show excellent performances for the integrated system, both in terms of flow control and pollution mitigation. The pollution, using biological oxygen demand concentration as a proxy of the whole load, was decreased by more than 90% and downstream flooding situations were avoided, despite the spillway was not regulated. Concerning the economic point of view, from a rough estimate of the costs, the system allows reducing the investment of 30 to 50% in respect to the traditional CSO controls based solely on flow detention tanks. The proposed approach, as well as the modelling framework for its effective implementation, appear strongly scalable in different world contexts and aim to fill the gap between urban and rural environments in the management of stormwater and CSOs, promoting the involvement of the water managers, the irrigation-reclamation agencies and regional authorities.

scholarly journals The Impacts of Climate Change and Porous Pavements on Combined Sewer Overflows: A Case Study of the City of Buffalo, New York, USA

2021 ◽  
Vol 3 ◽  
Author(s):  
Andrew Roseboro ◽  
Maria Nariné Torres ◽  
Zhenduo Zhu ◽  
Alan J. Rabideau
Keyword(s):  
Climate Change ◽  
New York ◽  
Combined Sewer Overflows ◽  
Aquatic Life ◽  
Impact Of Climate Change ◽  
Combined Sewer ◽  
Sewer Overflows ◽  
The Impact ◽  
The City

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.

The effect of decentral stormwater use in urban areas on pollution emission

1997 ◽  
Vol 36 (8-9) ◽  
pp. 149-154
Author(s):  
Th. Bettmann ◽  
M.W. Ostrowski
Keyword(s):  
Case Studies ◽  
Urban Areas ◽  
Simulation Models ◽  
Urban Drainage ◽  
Combined Sewer Overflows ◽  
Pollutant Loads ◽  
Pollution Emission ◽  
Drainage Networks ◽  
Combined Sewer ◽  
Remarkable Reduction

Remaining emissions from urban drainage networks are often caused by combined sewer overflows. The paper demonstrates the coupling of two simulation models for urban drainage and decentral stormwater usage. Some case studies show that the implementation of stormwater usage tanks will lead to a remarkable reduction of pollutant loads emitted.

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