the ripple effect

The ripple effect | 1

The ripple effecTBuilding resilience of urban water systems to climate change

executive Summary:The case for Birmingham and coventry

02 | The ripple effect

The ripple effect: Building resilience of urban water systems to climate change

This booklet examines the possible effects of climate change on urban water systems and proposes a method for identifying ways to build resilience in a cost effective way. It applies the principles of water sensitive urban design and integrated catchment management to propose holistic solutions. This research was commissioned by the UK Technology Strategy Board and Defra and carried out by AECOM and Severn Trent Water in collaboration with Birmingham City Council and Coventry City Council.

Water is central to the vitality of urban centres

Urban areas are also a nexus where a range of water issues are at their most extreme

water supply

recreation and joy

irrigation of food and trees tr

ansport of goods and people recreation food

high water demand

concentrated f ood risk

creation of polluted urban runoff generation of large amounts of wastewater


Climate risks and opportunities for water systems in urban areas

Flooding Winter rainfall is expected to increase 13% by 2050 in the West Midlands, increasing food risk from rivers, surface water runoff and groundwater. Urban areas are particularly vulnerable due to concentrated populations, infrastructure and business activity.

Population Growth and Liveability By 2020, the UK is expected to grow nearly 8% to 67.2 million. Both Birmingham and Coventry will experience significant growth. This will place added stress on existing water infrastructure but also on our urban areas to remain desirable, green and attractive places to live.

Water Stress Water supplies will be challenged in the future as river fows could decrease as much as 20% in the UK. Simultaneously, our demand for water will increase with hotter summers, meaning demand will outstrip supply.

Urban Heat By 2080 climate change is predicted to be responsible for a 540% increase in heat-related deaths in the UK, with five heat waves expected in Birmingham per year. Those living in urban areas will suffer the greatest impact due to the urban heat island effect.

River Quality Reduced stream fow is predicted to negatively impact river quality with the concentration of pollutants in England and Wales predicted to increase by 10% by the 2020s. Urban areas generate a large amount of pollutants from runoff and wastewater overfows.

Scope: Understand the context Test: explore with local stakeholders Refine: Identify ‘Areas of Opportunity’ Scope: identify possible interventions Test: Bring stakeholders together Refine: Create a vision Scope: identify business case metrics Test: Obtain metrics where possible Refine: Calculate the value

Research the climate change predictions for the area, the urban water context (including water supply, wastewater generation, surface water runoff, water course condition and existing infrastructure) and identify regeneration and development areas where the city is changing.

Test and supplement the context research by talking with local stakeholders who have a working knowledge of the city. Partners should be identified who work with water management, climate change and urban planning.

By finding opportunities where change is naturally happening, building resilience will become cost effective. This is the stage to focus in on a few areas of opportunity where there are natural drivers for change as well as the opportunity to address water related issues. This is also an opportune time for a site visit to see what is possible and what inspires.

Look at each of the ‘Areas of Opportunity’ in more detail, gaining site specific data from local partners. What are the site’s assets? What are the key issues on site that need to be addressed? What is the underlying existing infrastructure? Answers to these questions will naturally provide an answer to the best types of interventions to be included.

Test and identify possible interventions in partnership with a group of local stakeholders and partners, including water companies, councils, regulators and local community and wildlife groups. Consulting with local stakeholders will help create more robust interventions and identify potential funding sources. This is an ideal time for a workshop if one is to be held.

Assimilating the ideas identified will provide a complete picture of all the possible interventions. Create a priority list of interventions which are likely to bring the most value and be the most deliverable. Complete concept design for these interventions.

With the interventions determined, it is possible to begin the process of building a business case. Here, it is important to think about what benefits each partner will be interested in. Start to identify metrics which could be valued to build a business case.

With a skeleton business case developed, consult stakeholders to evaluate locally specific indicators and ensure the business case is robust. This process should ensure all parties’ interests are met and key drivers are recognised.

To build resilience quickly and effectively, we should drive cost-beneficial interventions founded on a clear business case that attributes benefits to delivery partners. The final stage evaluates the benefits in monetary terms where possible and identifies the outline cost (which should be significantly reduced in areas where redevelopment will drive change regardless). Ideally, site-specific analysis should be used to calculate the benefits; however, sourcing data from reputable sources, and extrapolating numbers based on other case studies is also possible.

Methodology: Working with partners to build resilience

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Finding the opportunities for change in Coventry

In Coventry, the Ringway (A4053) provides a natural boundary to the city centre. The majority of the city centre is already planned for extensive regeneration, with redevelopment areas concentrated in the central and southern area linking to railway station.

City Council

A 4600

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Regeneration areas

Canal

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River (culverted)

Main roads

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Regeneration areas


Local water system issues

Hidden river The River Sherbourne is a culverted river that hides beneath the city centre. As a culverted river, it cannot support life and has poor water quality. It also presents a food risk to the city if it becomes blocked or overwhelmed by an extreme storm event.

Surface water runoff As a highly built up and impermeable centre, surface water runoff is a significant cause of food risk and pollution. Coventry also has a clear demand for urban greening which will help permeability. Water has an interconnected relationship with greening, whereby urban planting will require water, but can also act to clean water, manage runoff and manage the urban heat island effect through evapo-transpiration.

Water efficiency Reducing water demand will help to build resilience of water supply in the West Midlands for the future. Water affordability is also a concern for local communities.


Focus area

Regeneration areas

Canal

River

Main roads

Landmarks

The NIA

Centenary Sq. Bullring

shopping centre

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A4540 A4540

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Finding the opportunities for change in Birmingham

In Birmingham, the Big City Plan sets out a vision for regeneration. Two of the largest areas for planned regeneration are the Eastside and the Southern Gateway. The Southern Gateway and its surrounds have been selected as the focus area for this study.

Regeneration areas


Focus area

Regeneration areas

Canal

River

Main roads

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Local water system issues: Birmingham

Water supply Water supply in Birmingham is heavily reliant on a single source from Wales. There is a need to source alternative sources of water to prevent relying on a single source. Additional supplies will also help to ensure that water supply meets demand in the coming decades.

Urban fooding During storm events, fooding presents a risk to Birmingham, and could occur from a combination of surface water, groundwater and river fooding. This will only be exacerbated as climate change is expected to increase runoff 8% by 2055.

Celebrating watercourses The River Rea’s quality has received the Environment Agency’s lowest ranking of ‘bad’. Improving this quality is a priority to strengthen the ecosystem’s resilience now and in the future. The Rea is also the focus of a regeneration area in the Southern Gateway.

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Climate change risk addressed

Flooding Water Stress Water Quality

Population Growth and Liveability Urban HeatIntervention Explanation

Water efficiency

GREEN ROOFS

Water efficiency will ease water supply and reduce wastewater production but also lower energy use.

●Rainwater runoff recycling

GREEN ROOFS

Capture, store, and reuse rainwater for non-potable uses. Can be employed at a building or site-wide scale.

● ● ●Wastewater recycling

GREEN ROOFS

Greywater or wastewater can be captured for reuse as a non-potable source. Can be employed at a building or site-wide scale.

● ●Groundwater abstraction

Groundwater abstraction could be an option in areas with high groundwater to reduce water stress and food risk.

● ●Underground infrastructure renewal

Water supply and drainage pipes can be replaced to reduce leakage and groundwater infux. Additional capacity can be added to accommodate growth. This is most opportunistic in regeneration areas.

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Sewer separation

Increasing the network of dedicated storm sewers in place of combined sewers to enable better control of water quality and sewer food risk. This could also add capacity for population growth.

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Key● Benefit

● Possible benefit

Matching opportunities to climate risk

Climate change risk addressed

Flooding Water Stress Water Quality

Population Growth and Liveability Urban HeatIntervention Explanation

Green roofs

GREEN ROOFS

Reduce surface water runoff, and increase green infrastructure and its associated benefits.

● ● ● ●Water feature storage (in hardscape or softscape areas)

GREEN ROOFS

GREEN ROOFS

Canals or other built water features could be designed with capacity to accept runoff during significant storms, attenuate fows, and prevent fooding. Captured water could be reused locally as a water source.

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Green sustainable drainage systems (SuDS) in streetsGREEN ROOFS

Incorporating raingardens, swales and/or tree pits that absorb runoff along streets will reduce fooding, improve water quality, provide irrigation water to trees and improve amenity.

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Daylighting water courses

GREEN ROOFS

Deculverting waterways in urban centres will improve water quality, provide more direct food management and improve amenity.

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In-situ river treatment

Provision of cleansing methods within the river.

●Flood resilient development

Designing buildings and public spaces to accept food water without significant damage. ● ●

Key● Benefit

● Possible benefit


The OppORTunITy And The BusIness CAseCOvenTRy

piece by piece: Bringing together small interventions to achieve a greater aim


Green roofs

Public space water feature

Street/SuDS retrofit

Surface water runoff recycling

Waste water recycling

Large scale water treatment and storage

River daylighting

Water efficiency

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Resilience strategy

In Coventry, the potential for regeneration across the city centre was made up of a large number of individual sites and opportunities where a variety of interventions could be delivered to begin a process of building resilience. By implementing these interventions alongside small scale regeneration initiatives, a cumulative effect will be achieved over time. The potential interventions are divided into three categories which address the key water risks for Coventry: working better with watercourses, minimising runoff, and improving water efficiency.


Working better with watercourses Naul’s Park and Swanswell Park Two culverted tributaries of the River Sherbourne gather runoff from the northern suburbs of Coventry and join the Sherbourne in the city centre. There is an opportunity to ‘daylight’ the culvert in the park areas to provide additional food storage as well as offine water treatment. Treated water could also be stored for reuse in nearby buildings and landscapes.

Daylighting River Sherbourne at Burges The Sherbourne is predominantly underground in the city centre, aside from a small and neglected open area near Burges Street. There is an opportunity to open up (daylight) the Sherbourne across a greater length on an under-utilised site opposite the Transportation Museum off Burges Street. This could provide additional food storage space and minimise risk of fooding via underground sewers, and also allow urban runoff to be treated then discharged directly to the river without entering the combined sewer system. By opening up the river, water will be used to animate the city centre, attracting community and commerce to the city centre, and providing the opportunity to create excellent public realm and walking routes. Exposing the river to light and oxygen and naturalising the edges with planting, will also improve water quality.

Butts Road green space There is substantial food risk in the area where the river enters the culvert. Before the river enters the culvert off Butts Lane, there is an opportunity to improve food storage, improve access to the river, and take advantage of existing green space and improve opportunities for recreation in the process.

Ikea public realm The River Sherbourne runs directly beneath the front entrance of the store where there is a large paved public realm area. There is potential to daylight the river here and create public realm that celebrates the river while providing food storage and water quality improvements. This is one of a few sites which could be delivered in the short term to form the catalyst for eventually daylighting the river throughout Coventry’s city centre.

Minimising runoff City centre south regeneration area Including water features and raingardens in the city centre is a prime opportunity to celebrate water as an urban design tool while storing and treating runoff. The captured water could be harvested for reuse in neighbouring buildings to reduce dependence on water mains. Key buildings in this area could also include green roofs to improve urban cooling and reduce runoff further. Green streets SuDS retrofit By introducing raingardens and raingarden tree pits on heavily pedestrianised streets in Coventry, including Friar’s Road, New Union Street, Stoney Road and Park Road, runoff from roads will be used to water plants, whilst being slowed and treated to reduce pressure on underground drains. This will add greenery and reduce road traffic, thus increasing land values, reduce air pollution, and improving urban biodiversity. Downpipes could also be disconnected on adjacent properties to allow rainwater to soak into the ground, replenishing groundwater and relieving pressure on sewer infrastructure.

Greyfriars Green Walking from the Coventry train station, Greyfriars Green is visitors’ first impression of the city centre. Using the park to capture, treat and store runoff from surrounding roads would create a water feature that celebrates water as a central theme in Coventry.

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Water efficiency Residential neighbourhood retrofit Residential neighbourhoods, such as the one near Holyhead Road to the northwest, can be retrofitted with water efficient taps and fittings in homes. On a larger scale, rainwater or greywater harvesting can be implemented to provide an additional water supply and reduce demand. These streets could also be retrofitted with SuDS measures to reduce runoff. By focussing on a community at a time, a scheme can increase community cohesion and create a uniting point of identity.

Coventry University retrofit As a centre of promoting advances in education, Coventry University has the ability to incorporate an array of initiatives to create a more resilient city while using it as an opportunity to learn and demonstrate. Constructing green roofs, incorporating rainwater harvesting, surface water runoff recycling, and water efficiency measures are all good measures to be undertaken.

Coventry City Council water neutrality As part of the energy efficiency retrofits in council-owned buildings, there is also an opportunity to retrofit more water efficient fixtures and appliances. Water recycling is another opportunity to supply water for fushing toilets. Coventry has an additional opportunity to drive a communal non-potable network, following the example of the Heatline district heating network where council buildings are used as a catalyst for a wider system. A non-potable network could be fed by rainwater or recycled wastewater.

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The initiatives shaded in blue have been taken forward for business case testing.


Naul’s Park before intervention: The culverted tributary, located directly under the mirror pond to the south of the site, fows directly into the River Sherbourne.

Visualisation of Naul’s Park wetland

Naul’s Park after intervention: The tributary is daylighted and includes extra width for food storage. Some of the fow is taken into an offine wetland for treatment. An underground storage tank stores some treated water for reuse for irrigation and toilet fushing in surrounding buildings.

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River Sherbourne at Burges before intervention: River is neglected and hidden beneath an underutilised and in-part derelict block.

River Sherbourne at Burges after intervention: Providing a pleasant and attractive public space which is adaptable to make space for higher water levels during heavy rainfall.

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Green streets retrofit: Stoney Road before intervention

Green streets retrofit: Stoney Road after intervention

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Business Cases for Coventry Interventions

Two business cases have been developed in Coventry focusing on the city’s two biggest opportunities: opening up the River Sherbourne and retrofitting green SuDS in streets to better manage runoff. The cost-benefit analysis assumes a 40-year lifetime and calculates a present value based on a 3% discount rate.

Environment Agency• Flood protection:

Daylighting the river would reduce the risk of fooding in Coventry due to the culvert being overwhelmed, reducing insurance liability from fooding up to £1,127,000 over 40 years.

• Water quality: Improving 5 kilometres of the River Sherbourne from ‘poor’ to ‘moderate’ quality could be worth as much as £2,772,000 over 40 years.

Severn Trent Water• Alleviating sewer

fooding: If a food event occurred due to a blockage of the culvert, or an extreme weather event, there would be cost implications for Severn Trent Water as water if water backed up through the sewer network.

Property Owner• Property values:

Riverside property is known to be more valuable. The average 24.2% uplift in rent value could be worth £63.2 million.

• Retail expenditure: Daylighting the river will improve both urban and environmental design. Research has shown that high quality design has a positive impact upon retail performance. With public realm improvements in Coventry’s retail centre, footfall could increase by up to 25%.

Council• Biodiversity and habitat

provision: The value attributed to biodiversity & habitat provision is estimated at £1,000 per 100m of river length. At 1.7km, the River Sherbourne could be worth £393,000 in habitat provision over 40 years.

• Regeneration, public access, and pedestrian links: While difficult to monetise, there are many benefits to the community’s well-being, such as improving the public realm and access to it. Council will also recoup taxes from increase in land values.

• Urban heat island: There will be an estimated 15 heat wave days per year in Coventry by 2080, resulting in 6.4 lives lost due to heat. Daylighting the river will mitigate heat gain in the city, and potentially reduce the number of deaths.

The present value of the monetised benefits calculated above equate to a city-wide benefit value of approximately £67.5 million. Scaling down to the Burges site, the benefit value over 40 years is calculated to be £12.8 million, 3.8 times more than the intervention costs of £3.3 million.

Business case 1: Daylighting the River SherbourneThe cost of daylighting the River Sherbourne at the Burges site across from the Transport Museum is estimated to cost £3,300,000. However, the benefits of daylighting the river accrue to individuals and organisations differently. The benefits have been assessed for the daylighting of the whole city centre section then re-apportioned.

Environment Agency• Improved river quality:

SuDS will reduce pollution of the River Sherbourne, and if it improves to ‘moderate’ quality across its entire length this benefit would be worth £4.1 million over 40 years.

• Groundwater recharge and rainwater reuse: If only half of the available rainwater runoff from Coventry was stored and reused as a water supply, the value of that water source could be as high as £6.7 billion.

Business case 2: Stoney Road green SuDS street retrofitRetrofitting a 335m section of Stoney Road near the railway station with green SuDS in both the roadway and properties has an estimated cost of £121,000. Costs for re-use of runoff as a non-potable source have not been estimated but this is a beneficial opportunity.The benefits are vast and varying in who they will affect. These benefits have been calculated for the City of Coventry as a whole then re-apportioned to the Stoney Road section.

Severn Trent Water• Alleviating sewer

fooding: Reducing incidents of sewer fooding would save the city £3.6 million per year or £83 million over 40 years.

• Less wastewater to manage: Implementing sustainable drainage techniques can reduce pumping and treatment costs by as much as £296,000 per year or £6.9 million over 40 years.

Property Owner• Property values: The

uplift in resale value for a property on a tree-lined street equates an average of 7%. The combined value of retrofitting all of Coventry with street trees could increase property values by a total of £1.2 billion.

• Energy cost savings: The energy savings per tree from wind protection in the winter and shade in the summer have been estimated to create energy savings of more than £48.8 million for Coventry as a whole.

• Lower drainage bills: Severn Trent allows customers to claim back surface water drainage charges, provided the runoff does not fow into the sewer. This would result in a benefit of £131 million over 40 years if all Coventry households were to control runoff at source.

Council• Carbon dioxide sequestration:

If more than 66,000 trees were planted in Coventry, CO2 sequestration could be worth up to £100,000 over 40 years.

• Air quality: The new trees could remove 15.8 tonnes of pollutants, worth approximately £12 million over 40 years.

• Biodiversity: When street trees are planted on a city wide scale, functional ecological corridors can be established, improving habitats in the process.

• Home zones and health: Residents of walkable neighbourhoods do 30-45 minutes more activity per week and are less likely to be obese or overweight.

• Urban heat island: Coventry will experience 15 heat wave days per year by 2080, resulting in 6.4 lives lost due to heat. A 10% increase in tree canopy can reduce temperatures by 2.5 degrees Celsius, potentially avoiding these deaths.

• Job creation: The jobs created as a result of retrofitting green SuDS could be worth more than £7.4 million.

In total, the benefits of retrofitting green SuDS at a city-wide scale are valued at over £1.5 billion over 40 years. Scaling down to Stoney Road suggests a calculated benefit of £906,000, or 7.5 times the site costs of £121,000. If water reuse infrastructure is included to store and recycle runoff, benefits increase dramatically to nearly £8.3-billion across the city, and nearly £3-million at the site scale.


The OppORTunITy And The BusIness CAseBIRmInghAm

The bigger picture: creating a water sensitive masterplan for the southern gateway


There is an exciting opportunity to integrate best practice water management into the Southern Gateway masterplan which will embed future resilience. By planning across a large area, there is a business case to use economies of scale to drive communal systems and large connected interventions. The city’s vision for the site includes the need to integrate the Bullring shopping centre, Highgate Park, and the River Rea. The result is an ecological ‘green cross’ which runs from the Bullring to Highgate Park and along the River Rea. Water management will be integral to the green cross, with the Bullring to Highgate Park axis providing the opportunity to capture, treat, store and convey runoff to the river while enlivening an interesting public corridor. The River Rea axis provides an opportunity to improve the river edges. While the approach taken in Coventry selected specific smaller sites for specific interventions, Birmingham’s opportunity is to take a more strategic masterplanning approach. Key water management principles and interventions are set out to address the three key issues of surface water runoff management, celebrating the Rea and creating water supply resilience.

Public space water feature

Surface water runoff recycling

River naturalisation

Regeneration areas

Green and blue corridors

Highgate Park

River

Canal

Water main

GREEN ROOFS

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Resilience Strategy

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Surface Water Management Wet boulevard (in green cross): A direct downwards sloping pedestrian route could be made from the Bullring shopping centre towards the River Rea. Strategically this could be a central ‘blue-green corridor’ used to capture, treat and store rainwater runoff from the surrounding area. A pedestrian-focused link with integrated water features and raingardens designed as SuDS to capture, treat and slowly channel runoff from a wider area to the Rea could be developed. Water collected from the wet boulevard could also be reused in a neighbouring development to supplement non-potable water supply. This project could form the backbone of the Southern Gateway’s climate adaptive response. There is also potential to create a similar wet boulevard on the otherside of the river capturing water from the eastern side of the regeneration area.

Celebrating the Rea Optimising access to the River Rea and softening the

river corridor: While the River Rea runs through Birmingham, access to it is poor. Opening the River Rea will require making better use of the river’s adjacent land uses and create pedestrian and recreation links. Increasing building setbacks to create public open space can improve Birmingham’s urban design, create recreation space, and attenuate surface water runoff before entering the river. Softening the river edges also provides opportunities to improve river quality and biodiversity.

Using under-utilised sites for runoff capture and filtration:

Development areas along the River Rea are an opportunity to capture and treat urban runoff at the catchment low point, thus mitigating food risk and improving river quality by removing pollution. This will remove rainwater fows from the sewer system and reduce risk of sewer fooding. Pilot sites have been identified at the intersection of Digbeth High Street and Rea Street and around the intersection of Rea Street and Moseley Road. The area near the river around Moseley Road has been identified as a key food risk area, and adaptable built form could be installed here to capture, treat and store food waters.

Building Water Supply Resilience Site-wide water recycling: As one of Birmingham’s biggest climate change challenges, increasing the number of sources for water supply will require innovative thinking. Surface water runoff recycling, a process where rainwater is captured, treated and reused can help make the Southern Gateway less dependent on water mains, and ultimately more resilient. Wastewater recycling, which treats and reuses wastewater for non-potable uses by including a small-footprint treatment plant on-site is another opportunity. Irrigation, industry use and toilet fushing are the primary uses for non-potable water.

Groundwater storage for reuse: The soils in the Southern Gateway area are generally of low permeability, except for an area around the Rea, where conversely the groundwater level is likely to be high. Therefore, SuDS used on the site and in the wet boulevard will need to be designed to store water on the surface or at shallow depths. There is an existing borehole at Adelaide Street, which would be utilised to inject treated rainwater for storage then re-extraction. A water supply operation could then extract and distribute water for reuse. This would provide greater local water balance between wet and dry periods and gain a supply-demand benefit by reducing demand on wider water resources.

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Visualisation of a wet boulevard pedestrianised area (Source: Centre for Water Sensitive Cities)1

Site at intersection of Digbeth High Street (B4100) and Rea Street in Birmingham before intervention

After intervention - Underground surface water runoff pipes are intercepted, and directed to micro-wetlands to provide water treatment before discharging to the River Rea at intersection of Digbeth High Street and Rea Street in Birmingham

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River Rea as a new destination from the Bullring, linking through to Highgate Park

Existing status of River Rea hidden behind buildings and under roads

Proposed status of the River Rea public open space and focus of activity

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Business case for Birmingham

Business case 3: Water sensitive Southern GatewayAs a strategic masterplan, it is difficult to estimate the engineering and construction costs, however when built into vision early, many costs are likely to be marginal when delivered in an integrated way with utilities and public realm improvements. When delivered on scale, benefits are likely to be substantial and prove the case for investment.

One overall business case was developed for the Southern Gateway at a masterplan scale. The cost-benefit analysis assumes a 40-year lifetime and calculates a net present value based on a 3% discount rate.

Environment Agency• Water quality: Improving

the River Rea’s quality from ‘bad’ to ‘poor’ could be worth £580,000 over 40 years.

• Flood risk reduction: Insurance claims per household are estimated at up to £30,000 and £90,000 per commercial property. Therefore, reduction in food risk will have a significant financial risk reduction benefit across the area.

Severn Trent Water• Water security: Water

efficiency and water recycling initiatives will significantly reduce water demands. Birmingham currently relies on a single source of water supply. The avoided investment in new water sources could equate to a benefit of an estimated £430 million.

• Reduced water and wastewater pumping and treatment: Increased efficiency and reduction in operational costs could be worth as much as £906,000 over 40 years. There will also be carbon savings associated with this reduction.

• Mains renewal: Potential for renewing mains in the area, reducing leakage.

• Reduced volume of surface water entering the sewerage system: Collecting surface water would reduce the loading on the sewerage system, reducing sewer food risk and improving the quality of local water courses.

Property Owner• Higher residential property

values: Projected 20% increase in green space in the Southern Gateway would increase house values by over £29 million for the planned 2,600 new residential properties and existing properties.

• Higher commercial property values: Water as an amenity feature can increase commercial rent. Uplift for high quality public realm and a natural environment is estimated at £574 million over 40 years.

• Lower water bills and a new supply revenue: Water bill savings for householders and businesses in the area could be over £350,000 per year, equating to £8.1 million over 40 years.

• Reduction in surface water runoff bills: Surface water drainage charges, provided the runoff does not fow into the sewer. This would result in a benefit of £2.8-million

for householders.

Council• Urban heat island:

Birmingham will experience 15 heat wave days per year by 2080, resulting in 6.4 lives lost due to heat. A 10% increase in tree canopy can reduce temperatures by 2.5 degrees Celsius, potentially avoiding these deaths.

• Biodiversity and recreational links: While difficult to monetise, there are additional benefits in promoting healthy living through walking and cycling and creating ecological corridors through the city.

• Council tax: As property values increase, councils are likely to receive an increase in taxes, resulting in improved local services.

• Air quality: The delivery of trees and vegetation combined with SuDS will absorb air pollution, bringing significant health benefits.

The benefits monetised where Southern Gateway is created as a water sensitive place as part of its regeneration are estimated at more than £1.046 billion over a 40-year lifetime. This business case demonstrates that there is clear value in investing in improved and more resilient urban water systems in the regeneration of this area of Birmingham.


Building resilient urban water systems has the potential to deliver real and wide-ranging benefits. The most effective way of delivering these benefits is by bringing stakeholders together to consider multi-purpose solutions early in the planning process. Through collaboration, opportunities can be identified that exploit synergies and which can be implemented at a scale which will allow them to have the greatest effect at the lowest cost.

Regeneration and development areas can be great opportunities to improve urban water systems economically, and drive wider benefits. Equally, areas where there are urgent and evident needs for upgrades to water systems should be prioritised. Where these drivers

Key lessons: Collaboration, opportunities and benefits

combine, the business case is very clear. The business case will always change depending on the context, but it provides a way of understanding who will benefit and by how much, helping partners to join forces to deliver change and experience mutual benefit.

This type of opportunitistic approach to adaptation requires a commitment to re-thinking the traditional approach to both development and water systems, and requires organisations and stakeholders to work together early to create a shared vision. The ripple effect provides a methodology that can be repeated to drive collaborative opportunities and bring wider benefits to fruition.

The ripple effect for wider...

Collaboration

Opportunities

Benefits


Funded by Technical strategy Board and defrain partnership with Birmingham and coventry city councils

the ripple effect

Documents

urban water context

water stress water supplies

surface water runoff

existing water infrastructure

water course condition

severn trent water

range of water issues

urban heat island effect