Natural Flood Management (NFM) Knowledge System: Part 1 – Sustainable Urban Drainage Systems (SUDS) and Flood Management in Urban Areas

Janice Blanc, Scott Arthur, Grant Wright

Research output: Book/ReportCommissioned report

Abstract

Executive Summary
This report, one of three reports produced for CREW to verify the current state of knowledge on NFM, focuses on establishing the effectiveness of SUDS measures for flood management in urban areas, particularly in relation to performance under saturation conditions and long term efficiency as a device becomes established.
Although it is explicitly recognised that SUDS can also deliver water quality and amenity benefits, this report focuses only on runoff detention and retention. Specifically, this report examines the performance of devices with high or moderate potential for runoff volume reduction in detail (green roofs, rainwater harvesting, pervious paving, infiltration devices and swales), reviewing the available evidence relating to the impact that these different SUDS measures have on managing flood scenarios.
The review focused on SUDS performance with respect to the following key hydrological processes:
1.Retention - where flow is not passed forward (including infiltration)
2.Detention/attenuation – temporarily slowing or storing runoff.
3.Conveyance - the transportation of surface runoff away from the original source
4. Water harvesting - the direct capture and use of water from its
source.
A key outcome of the review has been to highlighted the uncertainty associated with the performance of SUDS devices. In some case this is due to the contrasting research methodologies and metrics. However, equally significant is the design, main tenance and catchment characteristics associated with the devices considered.
The research review also found that, regardless of the SUDS device considered, a number of environmental factors influence the performance of the device in managing runoff:
- The length of any preceding dry period: saturated systems are less efficient.
- The prevailing climate: devices perform differently in hot and cold climates depending on air temperature, wind conditions, humidity etc.
- Seasonal variation: performance varies throughout the year.
- The characteristics of a rain event: intensity and duration, temporal spacing of multiple events and intensities during an individual event.
With the exception green roofs, it was found that the devices considered could operate well during and/or soon after extended periods of rainfall. Although green roofs can retain significant volumes of rainfall, the research reviewed suggested that lightweight “extensive” roofs readily become saturated and then offer only modest detention. As highlighted in Table 1, one stratagem to mitigate against these problems on other types of device has been to update design methods to allow for a loss of efficiency over time or due to saturation. This approach, although it comes at a cost, underlies the design of permeable paving systems and its success is evidenced by their widespread use and
relatively low maintenance requirements. An alternative to this may be to provide additional retention / detention downstream.
LanguageEnglish
PublisherCREW - Centre of Expertise for Waters
Commissioning bodyCentre of Expertise for Waters
Publication statusPublished - 2012

Fingerprint

urban drainage
urban area
roof
runoff
infiltration
saturation
rainfall
climate
amenity
design method
rainwater
drainage system
humidity
spacing
environmental factor
seasonal variation
air temperature
catchment
water quality
water

Cite this

@book{1c64e216ca0c4743828e7176391c3812,
title = "Natural Flood Management (NFM) Knowledge System: Part 1 – Sustainable Urban Drainage Systems (SUDS) and Flood Management in Urban Areas",
abstract = "Executive SummaryThis report, one of three reports produced for CREW to verify the current state of knowledge on NFM, focuses on establishing the effectiveness of SUDS measures for flood management in urban areas, particularly in relation to performance under saturation conditions and long term efficiency as a device becomes established. Although it is explicitly recognised that SUDS can also deliver water quality and amenity benefits, this report focuses only on runoff detention and retention. Specifically, this report examines the performance of devices with high or moderate potential for runoff volume reduction in detail (green roofs, rainwater harvesting, pervious paving, infiltration devices and swales), reviewing the available evidence relating to the impact that these different SUDS measures have on managing flood scenarios. The review focused on SUDS performance with respect to the following key hydrological processes: 1.Retention - where flow is not passed forward (including infiltration)2.Detention/attenuation – temporarily slowing or storing runoff.3.Conveyance - the transportation of surface runoff away from the original source4. Water harvesting - the direct capture and use of water from itssource. A key outcome of the review has been to highlighted the uncertainty associated with the performance of SUDS devices. In some case this is due to the contrasting research methodologies and metrics. However, equally significant is the design, main tenance and catchment characteristics associated with the devices considered. The research review also found that, regardless of the SUDS device considered, a number of environmental factors influence the performance of the device in managing runoff:- The length of any preceding dry period: saturated systems are less efficient. - The prevailing climate: devices perform differently in hot and cold climates depending on air temperature, wind conditions, humidity etc.- Seasonal variation: performance varies throughout the year.- The characteristics of a rain event: intensity and duration, temporal spacing of multiple events and intensities during an individual event.With the exception green roofs, it was found that the devices considered could operate well during and/or soon after extended periods of rainfall. Although green roofs can retain significant volumes of rainfall, the research reviewed suggested that lightweight “extensive” roofs readily become saturated and then offer only modest detention. As highlighted in Table 1, one stratagem to mitigate against these problems on other types of device has been to update design methods to allow for a loss of efficiency over time or due to saturation. This approach, although it comes at a cost, underlies the design of permeable paving systems and its success is evidenced by their widespread use and relatively low maintenance requirements. An alternative to this may be to provide additional retention / detention downstream.",
author = "Janice Blanc and Scott Arthur and Grant Wright",
year = "2012",
language = "English",
publisher = "CREW - Centre of Expertise for Waters",

}

Natural Flood Management (NFM) Knowledge System: Part 1 – Sustainable Urban Drainage Systems (SUDS) and Flood Management in Urban Areas. / Blanc, Janice; Arthur, Scott; Wright, Grant.

CREW - Centre of Expertise for Waters, 2012.

Research output: Book/ReportCommissioned report

TY - BOOK

T1 - Natural Flood Management (NFM) Knowledge System: Part 1 – Sustainable Urban Drainage Systems (SUDS) and Flood Management in Urban Areas

AU - Blanc, Janice

AU - Arthur, Scott

AU - Wright, Grant

PY - 2012

Y1 - 2012

N2 - Executive SummaryThis report, one of three reports produced for CREW to verify the current state of knowledge on NFM, focuses on establishing the effectiveness of SUDS measures for flood management in urban areas, particularly in relation to performance under saturation conditions and long term efficiency as a device becomes established. Although it is explicitly recognised that SUDS can also deliver water quality and amenity benefits, this report focuses only on runoff detention and retention. Specifically, this report examines the performance of devices with high or moderate potential for runoff volume reduction in detail (green roofs, rainwater harvesting, pervious paving, infiltration devices and swales), reviewing the available evidence relating to the impact that these different SUDS measures have on managing flood scenarios. The review focused on SUDS performance with respect to the following key hydrological processes: 1.Retention - where flow is not passed forward (including infiltration)2.Detention/attenuation – temporarily slowing or storing runoff.3.Conveyance - the transportation of surface runoff away from the original source4. Water harvesting - the direct capture and use of water from itssource. A key outcome of the review has been to highlighted the uncertainty associated with the performance of SUDS devices. In some case this is due to the contrasting research methodologies and metrics. However, equally significant is the design, main tenance and catchment characteristics associated with the devices considered. The research review also found that, regardless of the SUDS device considered, a number of environmental factors influence the performance of the device in managing runoff:- The length of any preceding dry period: saturated systems are less efficient. - The prevailing climate: devices perform differently in hot and cold climates depending on air temperature, wind conditions, humidity etc.- Seasonal variation: performance varies throughout the year.- The characteristics of a rain event: intensity and duration, temporal spacing of multiple events and intensities during an individual event.With the exception green roofs, it was found that the devices considered could operate well during and/or soon after extended periods of rainfall. Although green roofs can retain significant volumes of rainfall, the research reviewed suggested that lightweight “extensive” roofs readily become saturated and then offer only modest detention. As highlighted in Table 1, one stratagem to mitigate against these problems on other types of device has been to update design methods to allow for a loss of efficiency over time or due to saturation. This approach, although it comes at a cost, underlies the design of permeable paving systems and its success is evidenced by their widespread use and relatively low maintenance requirements. An alternative to this may be to provide additional retention / detention downstream.

AB - Executive SummaryThis report, one of three reports produced for CREW to verify the current state of knowledge on NFM, focuses on establishing the effectiveness of SUDS measures for flood management in urban areas, particularly in relation to performance under saturation conditions and long term efficiency as a device becomes established. Although it is explicitly recognised that SUDS can also deliver water quality and amenity benefits, this report focuses only on runoff detention and retention. Specifically, this report examines the performance of devices with high or moderate potential for runoff volume reduction in detail (green roofs, rainwater harvesting, pervious paving, infiltration devices and swales), reviewing the available evidence relating to the impact that these different SUDS measures have on managing flood scenarios. The review focused on SUDS performance with respect to the following key hydrological processes: 1.Retention - where flow is not passed forward (including infiltration)2.Detention/attenuation – temporarily slowing or storing runoff.3.Conveyance - the transportation of surface runoff away from the original source4. Water harvesting - the direct capture and use of water from itssource. A key outcome of the review has been to highlighted the uncertainty associated with the performance of SUDS devices. In some case this is due to the contrasting research methodologies and metrics. However, equally significant is the design, main tenance and catchment characteristics associated with the devices considered. The research review also found that, regardless of the SUDS device considered, a number of environmental factors influence the performance of the device in managing runoff:- The length of any preceding dry period: saturated systems are less efficient. - The prevailing climate: devices perform differently in hot and cold climates depending on air temperature, wind conditions, humidity etc.- Seasonal variation: performance varies throughout the year.- The characteristics of a rain event: intensity and duration, temporal spacing of multiple events and intensities during an individual event.With the exception green roofs, it was found that the devices considered could operate well during and/or soon after extended periods of rainfall. Although green roofs can retain significant volumes of rainfall, the research reviewed suggested that lightweight “extensive” roofs readily become saturated and then offer only modest detention. As highlighted in Table 1, one stratagem to mitigate against these problems on other types of device has been to update design methods to allow for a loss of efficiency over time or due to saturation. This approach, although it comes at a cost, underlies the design of permeable paving systems and its success is evidenced by their widespread use and relatively low maintenance requirements. An alternative to this may be to provide additional retention / detention downstream.

M3 - Commissioned report

BT - Natural Flood Management (NFM) Knowledge System: Part 1 – Sustainable Urban Drainage Systems (SUDS) and Flood Management in Urban Areas

PB - CREW - Centre of Expertise for Waters

ER -