Hazel Wilson and Charlotte Viner (University of Nottingham) have recently been out and about doing fieldwork in the River Leen. They’ve been investigating the water quality, invertebrates, and habitat quality of the river as it flows through the city of Nottingham.

Background information

Urban rivers like the River Leen have been heavily impacted by humans to make space for development and to manage flood risk. They have often been straightened and cleared of habitat and vegetation, and many have problems with water quality. However, things have been improving in the last few decades as we’ve come to recognise the value of biodiversity and blue-green spaces.

In order to keep improving rivers we need to understand the current condition of the river, so we wanted to investigate the water and habitat quality by doing some fieldwork.

We had ten survey sites along the Leen (Figure 1). These sites were chosen to correspond to Environment Agency (EA) sites, so we can compare to their regular monitoring (they’ve kindly provided us with data since 2013), but we had additional sites to fill in the gaps.

Figure 1 : Sites monitored on the River Leen for this study. The red lines delineate the two Water
Framework Directive (WFD) (2000/60/EC) catchment areas used to classify the ecological status of the river: the upper catchment from source to Day Brook, and the lower catchment from Day Brook to the River Trent. Data from EA (2021b) and OS Open Rivers (2021).

Main research findings

Water quality and invertebrate communities in the River Leen

We found that water quality and invertebrate communities in the River Leen are generally good. Our data was broadly similar to what the EA have found, showing that water quality in particular has been improving in recent years. Figure 2 shows how soluble reactive phosphorus (SRP) concentrations have improved over time. High concentrations of this nutrient can lead to accelerated growth of algae and plants which can, in turn, impact oxygen levels and river habitat characteristics, leading to significantly altered community structures. However, SRP concentrations along the River Leen were low, indicating good or high status in recent years.

Figure 2. Soluble reactive phosphorus (SRP) concentrations for four sites on the River Leen for sample years 2013 to 2021. 2013-2017 data collected by the EA (2021a) and 2021 data collected during this study. The approximate threshold values between moderate and good, and good and high WFD classification standards are indicated by the black dotted lines.

Nutrient concentrations

We found that nutrient concentrations were greater downstream of the tributary with Day Brook. Preventing pollution by industry, wastewater treatment, and household misconnections could help improve matters for the Leen and Day Brook.

Habitat quality

We found that habitat quality decreased downstream in the catchment, which corresponded with an increase in modification of the river. There is a possibility of future river restoration to improve this, for example there have recently been works at Queens Medical Centre to stabilise flood defences and provide fish habitat.

Isolated pollution events

On some days and at some sites, we found higher pollution levels than was found at other sites/times. Regular longer-term monitoring at more sites could help us better understand whether isolated pollution events are occurring and how best to prevent them. For instance, after a period of heavy rainfall, we found higher (although not dangerous) levels of ammonia at our Mill Street Playing Fields sampling site.

Summary

Taken together, these results are good news as they show that conditions in the River Leen are fairly good considering the level of urbanisation of the catchment, and the improving conditions over time are promising for the future health of the river. We really enjoyed getting out and about on fieldwork and getting to know the River Leen a bit better!

The full report can be found at http://www.urbanfloodresilience.ac.uk/documents/the-health-of-the-river-leen.pdf.

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In this blog, Dick Fenner and Charlie Ferguson explore how Natural Flood Management (NFM) strategies in upstream rural parts of a catchment might influence the performance of urban drainage systems further downstream (through moderating water levels in urban watercourses).

Catchment-based flood management

It is estimated that there will be a general increase of between 5 and 25% in river flows during wet seasons in parts of England (Committee on Climate Change, 2016). To combat this a catchment-based flood management philosophy has emerged in recent years, which aims to use a series of spatially discrete interventions to evolve rural catchment uplands and reduce risk of downstream fluvial flooding (Lane, 2017). In certain catchments the use of NFM interventions will also influence how the downstream receiving watercourse interacts with urban drainage outfalls. Whilst the evidence for catchment scale NFM mitigating fluvial flooding in extreme rainfall remains inconclusive (Iacob et al., 2017), NFM solutions may improve the resiliency of urban surface water drainage during lesser events by moderating water levels in urban watercourses. This would reduce the submersion of frequently drowned drainage outfalls and promote free discharge from the urban system and thereby improve the effective capacity of the network.

There are several examples of detrimental impacts from inundated surface drainage outfalls, for example with outfall flaps in Birmingham being closed because of high water levels in the nearby River Rea (Ellis and Viavattene, 2014) leading to greater flood risk. Similarly the restrictive impact of high water levels in local streams on the surface water network in the Kent town of Paddock Wood has been identified as a critical flooding mechanism (Jackson Hyder Consulting, 2015). In Kingston upon Thames town centre and nearby Hogsmill Valley, high water levels in the local watercourse have been reported as blocking outfalls and creating extended periods of surcharging in the surface drainage network (Craven and Littlewood, 2011).

The 4 separate “flow states” in an urban watercourse with a flapped urban surface water outfall are shown in Figure 1 below:

Figure 1: Different flow states in an urban watercourse with a flapped surface drainage outfall (Ferguson and Fenner, 2020a)

Modelling approach

To study these effects a novel coupled modelling approach was adopted linking:

• Dynamic TOPMODEL (a long established semi-distributed and semi-conceptual hydrological response model which discretises a catchment into hydrologically similar Hydrological Response Units), with a
• 2D HEC-RAS model (which solves the full shallow flow equations using a finite element method and allows channel flows to be predicted at a downstream gauging station), with an Integrated
• INFOWORK ICM model (which provides the drainage response from the urban area with respect to changes on outfall inundation)

Details of the modelling methodology and the calibration procedures used can be found in Ferguson and Fenner (2020b).

Results from Case Study Catchments

The Bin Brook, Cambridgeshire

The Bin Brook Catchment (~18km²) is part of the Cam and Ely Ouse river basin in Cambridgeshire and drains an area west of Cambridge passing through rural, intensely farmed land before entering the city and draining to the River Cam in the city centre. There is a significant flood risk for an area of housing located on the fringe of Cambridge with 28 properties flooded in 2001 and several instances of surcharging and nuisance surface flooding reported since.

The impacts of four NFM scenarios were tested including the introduction of woody debris and  wider catchment afforestation, and attenuation of the catchment response created by these measures was evaluated for a historic event and six different design storms.

The water depths at two downstream drainage outfalls was investigated with respect to maintaining free discharge from the drainage system. The results showed that the greatest reductions in the time of outfall inundation from NFM occur during frequent storms. These reductions diminish with storm severity but, by slightly desynchronising rural and urban responses, upstream interventions have a modest benefit for downstream drainage performance (in this case preventing the system capacity being exceeded during a 1 in 100 year event).

The full results of this study have been published in the Journal of Flood Risk Management (see Ferguson and Fenner (2020a)).

The River Asker, Dorset

The River Asker drains a 48 km² area of western Dorset before passing through Bridport and then discharges into the English Channel. The catchment is principally grassland with pockets of arable farming and woodland. Water levels in the River Asker have influenced surface flooding with drainage unable to cope during intense pluvial events, frequently submerging an outfall from a nearby housing estate. Two forms of upstream catchment scale interventions were modelled to understand their impacts on the functioning of the drainage network during both the calibration period and for a range of design storms.

The results indicate the NFM interventions have the greatest impact on surface drainage performance during frequent storm events. For example, during a 1 in 10 year storm upstream NFM could reduce outfall inundation by 3.75 hours and remove any surcharging within the drainage system in Bridport. In more severe storms, the results suggest interventions could slightly prolong the time the outfall was submerged. By slowing the wider catchment response, upstream interventions allow more water to escape the urban drainage systems and reduce the maximum surface flooding extent within the housing estate by 35%.

The full results of this study have been published in the Royal Society’s Philosophical Transactions A (see Ferguson and Fenner (2020c)).

The River Calder, Yorkshire

The study focused on Todmorden in the headwaters of the Calderdale valley in West Yorkshire which was the UK’s worst affected borough during the Boxing Day floods in 2015 with over 2500 properties impacted, following previous serious flooding in 2012 and 2013, as well as more recently in February 2020. Local authorities believe that blocked surface drainage outfalls (resulting from heightened water levels in receiving urban watercourses) exacerbate surface flood risk (Calderdale Metropolitan Borough Council, 2019). Whilst the sub-catchment studied has no significant NFM projects currently underway, the recent flood history has fuelled projects across the wider Calderdale area. Two forms of potential interventions were studied including in-channel woody debris and cross slope tree planting. These were chosen because they reflect several physical implementation projects within adjacent sub-catchments of the River Calder and together they represent the impact of significant changes in land management practices in upper Calderdale.

The results suggest that catchment-scale tree planting and in-channel woody debris create modest benefits to the downstream drainage system in parts of Todmorden. Under frequent storm events (e.g. a 1 in 1 year storm) the inundation of low lying areas is completely removed. As storm severity increases (and surface flooding becomes an issue), impact from upstream NFM attenuation on outfall inundation durations diminishes significantly. However, the delay in rural response allows more water to escape surface water pipe systems, increasing the effective capacity of networks and reducing surface flooding. For instance, outfall inundation during an estimated 20 year event is delayed by 30 minutes which results in up to 25% reduction in surface flood volumes. While the benefits are limited in extent, the modelling indicates that NFM can moderate water levels and help improve downstream surface drainage performance in the area.

The full results of this study have been published in the Journal of Hydrology (see Ferguson and Fenner (2020c)).

Further work was carried out on the Calder catchment examining the urban responses under various storm tracks, based on five design events and eight different storm directions (Figure 2).

Figure 2: Calder Catchment with hypothetical NFM scenario and overlaid variable rainfall grid showing first three time steps of eight different storm directions (Ferguson and Fenner, 2021).

The results shows that Todmorden’s surface drainage is influenced by the degree of synchronisation between urban rainfall and heightened levels in the receiving watercourse. In particular, storms from the north and west lead to synchronisation of urban rainfall and outfall inundations, which hinders drainage performance. Conversely south and east storms result in the urban rainfall passing through the drainage system before outfalls are impeded.

The full results of this study have been published in the Journal of Water Management (see Ferguson and Fenner (2021)).

Overall Conclusions

Taken together these studies have shown that NFM interventions in upper rural catchments can contribute to water level management strategies by moderating water levels and promoting free discharge at surface drainage outfalls in downstream urban areas. In each catchment there is a “window” of events (defined by storm track and severity) where NFM could improve surface drainage performance and mitigate nuisance flooding in urban areas. The benefits are modest but could help engage local stakeholder and community support for wider catchment based mitigations.

References

1. Committee on Climate Change 2016 UK Climate Change Risk Assessment 2017 Synthesis Report (https://www.theccc.org.uk/wp-content/uploads/2016/07/UK-CCRA-2017-Synthesis-Report-Committee-on-Climate-Change.pdf)
2. Lane S.N. (2017) Natural Flood Management. Wiley Interdicsip. Rev. Water 4, 1-14 (doi:10.1002/wat2.1211)
3. Iacob O, Brown I., Rowan J., (2017) Natural flood management and climate tradeoffs : The case of the Tarland catchment, Scotland. Hydrological Sciences Journal 62(12) 1931-1948  (doi:10.1080/02626667.2017.1366657)
4. Ellis J.B., and Viavattene C. (2014) Sustainable Urban Drainage system modelling for managing urban surface water flood risk. Clean Sol, Air, Water 42 (2) 153-150 (org/10.1002/clen.201300225)
5. Jackson Hyder Consulting, (2015) Jackson Wood Flood Alleviation Study. Guildford. Retrieved from: https://www.kent.gov.uk/__data/assets/pdf_file/0004/35455/Paddock-Wood-SWMP-stage-2-report.pdf
6. Craven E. and Littlewood S., (2011) Surface Water Management Plan for the Royal Borough of Kingston upon Thames. Thames Water; Environment Agency; Greater London Authority; Royal Borough of Kingston.
7. Ferguson C., Fenner R.A, (2020a) The potential for natural flood management to maintain free discharge at urban drainage outfalls. Journal of flood Risk Management (doi:10.1111/jfr3.12617)
8. Ferguson C., and Fenner R.A. (2020b) The impact of Natural Flood Management on the performance of surface drainage systems: A case study in the Calder Valley. Journal of Hydrology 590, 125354 (org/10.1016/j.jhydrol.2020.125354)
9. Ferguson C., and Fenner R.A, (2020c) Evaluating the effectiveness of catchment-scale approaches in mitigating urban surface water flooding. Philosophical Transactions of the Royal Society A, 378, 2168 (org/10.1098/rsta.2019.0203)
10. Calderdale Metropolitan Borough Council (2019) Initial Event Analysis Report. Retrieved from https://www.calderdale.gov.uk/v2/sites/default/files/Initial-Event-Analysis-Report.pdf
11. Ferguson C., and Fenner R.A. (2021) How natural flood management helps downstream urban drainage in various storm direction. Proceedings of the Institution of Civil Engineers – Water Management (org/10.1680/jwama.19.00057)

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Dick Fenner (University of Cambridge) introduces the work of the Urban Flood Resilience research consortium that forms a core of papers for a special themed edition of the Royal Society’s Philosophical Transactions A Journal on urban flood resilience, published in February 2020. Details can be found on the special issue homepage.

The edition brings together the approach to urban flood resilience in the UK with contributions describing similar initiatives in other countries including the Netherlands, China, Australia, New Zealand and India. The challenges and goals in these countries are similar, requiring the restoration of the benefits of pre-development hydrology in rapidly growing urban centres using Blue-Green Infrastructure solutions to manage flood risk. So the need to develop ways of adapting to the increasing number, frequency and magnitude of damaging flood events in ways that are resilient and sustainable is the underlying premise behind this themed issue.

Urban flood resilience special issue (Philosophical Transactions of the Royal Society A journal)

These approaches can provide multi-functional assets which create a range of other benefits, contribute to wider practices of urban greening, and present real opportunities for enhancement of urban environments.

The papers have been contributed by authors from a wide range of disciplines including engineering, geography, planning, social science, hydrology, economics, and architecture. Whilst each reflects the norms and understanding of flood problems from the perspective of these different backgrounds, it is clear that solutions need to embrace all these various dimensions and never has the need for such a multi-disciplinary approach been so apparent.

Paradigm shift in flood risk management?

A paradigm shift is needed in flood risk management, whereby the solution is framed as an opportunity rather than seeing the problem as a risk. If approached from this perspective stormwater can be treated as a huge potential resource which can be used in some contexts for energy generation as well as providing an essential source of future water supplies. Using waterit in this way makes perfect sense rather than merely draining it “away”. Beyond that, the use of Blue-Green Infrastructure to manage stormwater provides a range of other important benefits from enhancing urban biodiversity through creation of new habitats, sequestering carbon and trapping air pollutants, and providing recreation and amenity opportunities for local communities.

Currently, urban flood risk management can present many messy problems where parts of both the problem and potential solutions are owned by a diverse range of stakeholders ranging from water utility companies, regulators, planners, and property owners, leading to complex and often fragmented responsibilities. Moreover, for flood schemes to be resilient they have to be acceptable to the local communities in whose locale they are situated. Thus solving urban flooding is no longer a solely technical problem, where solutions are imposed by specialist engineers and scientists responsible for understanding the physical responses of the systems. Instead, responses must be framed within a wide socio-technical system where many actors interact in often muddled ways. Hence the papers included in this special edition attempt to deal with all these critical aspects of urban flood resilience ranging from modelling and evaluating the performance attributes of flood resilient solutions, to perspectives from planning, governance and even the social psychology of the public’s awareness of the solutions available.

What is urban flood resilience?

The term “resilience” doesn’t have a generally consensual definition, despite it being regularly used in relation to Flood Risk Management. One definition of resilience provided by Sayers et al. [1] is: “ The ability of an individual, community, city or nation to resist, absorb or recover from a shock (such as an extreme flood) and/or successfully adapt to adversity or change in conditions (such as climate change  or economic downturn) in a timely and efficient manner”. Extending this further, community resilience is based on damage prevention, speedy recovery and preservation of community functionality [2].

In the Safe and SuRe Framework resilience is defined as “the degree to which the system minimises level of service failure magnitude and duration over its design life when subject to exceptional conditions” [3]. This is an example of engineering resilience where the key features are the resistance to disturbance and the speed of return to equilibrium. Other formulations refer to ecological resilience which sees resilience in a more dynamic way where the capacity to absorb the magnitude before changing its structure is the main feature [4]. Thus, engineering resilience focuses on efficiency, constancy and predictability while ecological resilience  focuses on persistence, change and unpredictability [5].

Overall Urban Flood Resilience can be captured in the following  three important aspects [6]:

• The capacity of maintaining resistance over a period of time
• The capacity of the affected communities to recover from material losses, and
• The capacity of the  drainage system to recover its functions and keep operating after the storm, guaranteeing  basic conditions for urban services  to return to normality.

Information about the spatial distribution of resilience is particularly valuable since well-targeted projects can enhance the surrounding areas considerably [4]. The different forms of resilience can be reflected by contrasting the engineering fail-safe approach with the ecological safe-to-fail response, noting that the challenge for flood management is to find more environmentally sound materials and technologies, whilst in the long term recognising the necessity to change our habits and lifestyle [7]. In reality, achieving urban flood resilience requires co-ordination across multiple levels of government. Multiple flood risk management strategies are required – coordinated across multiple governance layers – achieved by proactive policy entrepreneurs, bridging concepts, clear rules, and the provision of the necessary resources [8].

The focus of the themed edition is on encouraging the practical planning, design and implementation by practitioners of SuDS, Blue-Green Infrastructure and other related techniques, as these have the potential for transformative change of urban water systems.

Papers from the Urban Flood Resilience research consortium

From the Urban Flood Resilience consortium O’Donnell and Thorne contribute the first paper which reassesses the current drivers of urban flood risk, first established by the UK Flood Foresight Project over ten years ago. They suggest five drivers have strengthened and they  introduce two new drivers relating to loss of floodable urban spaces, and indirect economic impacts. This reappraisal frames the overall problem in the light of recent advances in flood risk science, technology and practice.

Two papers deal with different modelling approaches to examining aspects of urban flood resilience. Ferguson and Fenner use a novel coupled model linking Dynamic TOPMODEL, HEC-RAS and Infoworks ICM to explore the effect of Natural Flood Management (NFM) interventions in the Asker catchment (Dorset UK). Their paper investigates if moderating water levels in the urban receiving watercourse can be achieved by NFM to allow free drainage at frequently submerged drainage outlets, in this case from a housing estate in Bridport. A parallel systems approach is taken by Dawson, Vercruysse and Wright who combine hydrodynamic modelling with spatial information on infrastructure systems to explore how flood management interventions can be inter-operably connected. Applied to the urban catchment of Newcastle-upon-Tyne, their findings illustrate the benefits of combining data sources in a systematic and spatial way, highlighting the interactions between flood source areas (where most intervention are required) and flood benefit areas (where most of the reduction in flooding is achieved).

Two more papers from the consortium follow which examine the planning and performance of Blue-Green Infrastructure and SuDS systems. Kapetas and Fenner present an adaptive pathways approach to answer the question: what is the most suitable mix of grey and blue-green solutions to urban flooding at any given location and at any future time. A methodological framework is applied to a small sub-catchment in south London using a Storm Water Management Model (SWMM), a SuDS opportunity selection tool, and an adaptation pathways generator. The CIRIA B£ST tool is then used to monetise and compare the multiple benefits of the alternative pathways generated (using combinations of grey pipe expansion, bioretention cells, permeable pavements and storage ponds). Krivtsov, Birkinshaw et al. report the performance of a historic pond in the Royal Botanic Garden Edinburgh which regulates surface runoff, using the CityCAT hydrodynamic model and the Shetran hydrological model, as well as assessing the ecology and biodiversity of the pond and adjacent area, giving insights into the benefits such a facility can provide.

The edition then moves on to considering diverse insights on the impacts of urban flood resilience measures from planning, community stakeholder, recovery, governance, regulatory and economic perspectives. Potter and Vilcan examine how resilience thinking can be implemented despite the realities of English planning procedures. They find three institutional factors constraining the implementation of SuDS, namely the lack of institutional backing, the power of private commercial interests and the severe lack of resources in local authorities which, if not addressed, will ensure resilience approaches remain largely aspirational. A novel application of the Implicit Association Test is used by O’Donnell, Maskrey, Everett and Lamond to investigate unconscious perceptions of SuDS, which can help inform future SuDS design to increase their public acceptance.

Summary

Provision of traditional flood control measures follow a logical progression starting with hydrological studies, selection of a design storm of a suitable return period, and the design and subsequent implementation of an engineered system to convey the flow generated. However, there will always be the risk of the system being overwhelmed by a hydrological event which exceeds the design storm, in addition to the eventually of the physical failure of the assets. Disregarding these residual risks can lead to a false sense of security and create increased exposure to hazard in urban environments. These traditional, inflexible, often centralised and increasingly deteriorating assets are failing more frequently as climate and other drivers of flood risk rapidly strengthen, whilst responsibilities are complex, convoluted and opaque.

The special themed edition closes by calling for a new paradigm in which “an integrated approach to managing the water cycle begins by seeing potential opportunities, exploiting resources, adding to the quality of urban areas and preferring nature-based approaches, seeking multi- value and multi-functional infrastructure” [9]. To do otherwise may be seen as a transgression from the inevitably of natural laws, attempting to hold back the tide – if you will.

Details of the urban flood resilience special issue

References

1. Sayer P., Li Y., Galloway G., Penning-Rowsell E., Shen F., Kang W., Yiwei C., Quesne T.I. (2012) Flood Risk Management: A Strategic Approach. Paris, UNESCO.
2. Birkland T.A., Waterman S. (2009) The politics and policy challenges of disaster resilience in C.P. Nemeth, E. Holnagel, S. Dekker Resilience engineering perspectives . Vol 2 Preparation and  Restoration  Ashgate Publishing Limited  Surrey UK pp 15-38
3. Butler D, Farmani R, Fu G, Ward S, Diao K, Astaraie-Imani M. (2014) A new approach to urban water management: Safe and sure, Procedia Engineering, volume 89, no. C, pages  347-354, DOI:10.1016/j.proeng.2014.11.198
4. Bertillson L., Wiklund K., de Moura Tebaldi I., Rezende O.M., Verol A.P., Miguez M.G. (2018) Urban flood resilience – a multi criteria index to integrate flood resilience into urban planning. Journal of Hydrology, 573, 970-982.
5. Holling C.S (1996) engineering resilience versus ecological resilience In Shultze P.C., (ed) Engineering within Ecological Constarints, National Academy Press, Washington  Dc, USA
6. Miguez  M.G., Verol A.P (2017) A catchment scale Urban Flood Resilience Index  to support decision  making  in urban flood control design. Environ. Plann.. B : Urban Anal City Science 44, pages 925-946
7. Abdulkareem M, Elkadi H., (2018) From engineering to evolutionary, an overarching approach in identifying the resilience of urban design to flood. International Journal of Disaster risk reduction Vol 28 pp 176-190
8. Dieperink C., Mees H., Priest S.J., Ek K., Bruzzone S., larrue C., Matczak P., (2018) Managing urban flood resilience as a multilevel governance challenge: an analysis of required multilevel coordination mechanisms  Ecology and  Society Vol 123 No 1
9. Ashley R, Gersonius B, Horton B. 2020 Managing flooding: from a problem to an opportunity. Phil. Trans. R. Soc. A 378, 20190214. (doi:10.1098/rsta.2019.214)

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Lessons are being drawn from the near breach of Toddbrook reservoir dam concerning the vulnerability of the UK’s infrastructure to extreme events. Karen Potter reflects on the implications of the risk, liability and responsibility of ‘Toddbrooks’ being devolved to civil society.

Flood risk and emergency response

On August 1^st 2019 approximately 1,500 residents in the Derbyshire town of Whaley Bridge were instructed to evacuate their homes, after the nearby Toddbrook reservoir dam threatened to breach following a period of extreme rainfall (Broomhead, 2019; Pidd et al., 2019). According to the incident commander, it had been a very, very tense night and a near miss from dam failure (Parveen, 2019).

A round-the-clock, multi-agency emergency response averted any disaster. This included the Derbyshire Constabulary, Fire and Rescue Service, the Environment Agency, Derbyshire County Council (e.g. the Emergency Planning Officers), High Peak District Council, the Canal and River Trust, and everyone who supported the people of Whaley Bridge and surrounding areas with the evacuation. With the aid of an RAF Chinook helicopter over 500 hundred bags of aggregate were dropped to reinforce the dam wall, and over the course of a week the reservoir’s water levels were drawn down by over ten metres until almost empty (Jowitt, 2019). The emergency services, military personnel, Environment Agency and volunteers were praised by the media and Government for their heroic effort, and many tributes have been paid to the wonderful community support, spirit and fortitude in Whaley Bridge (Defra et al., 2019). Residents were allowed to return to their homes a week later, and the focus has now turned from the emergency response to the Secretary of State’s (Theresa Villiers) commissioned review, which is set to investigate “what might have led to the damage, whether there was anything that could have prevent or predicted it and identify any lessons learned” (Hansard, 03 September 2019).

Toddbrook reservoir prior to the summer 2019 rainfall event. Photo credit: David Lee.

Identifying lessons learned – missing the governance implications?

Experts assert the main lesson from the Whaley Bridge dam scare is that the maintenance of dam spillways cannot be ignored, in any circumstances or at any cost (Heidarzadeh, 2019).

The incident has also been taken as a broader warning that the UK’s infrastructure is not up to scratch in the face of climate change and the Government is not acting quickly enough or committing enough resources to upgrade it (Weaver and Laville, 2019). The Government has consequently faced calls for an urgent overhaul of flood defences and water infrastructure and to put climate resilience at the top of the spending list (ibid).

What has not yet been highlighted or debated to any extent following the scare, is that the ownership of Toddbrook Reservoir lies with a charity – the Canal and River Trust. Should a charity take on this level of risk, liability and responsibility for the maintenance and upgrading of major infrastructure? If so, will the raising of climate resilience to the top of the Canal and River Trust’s list come with a serious commitment to increased support and resources from Government?

The creation of a new charity at the heart of our Civil Society

“The creation of a new charity will place the waterways firmly at the heart of civil society” (Defra, 2011, p1)

The Canal and River Trust protects the nation’s heritage, with 3,200km of historic canals and river navigations in England & Wales, more than 1,580 locks, 2980 bridges, 758 major embankments, 1,931 culverts, 73 pumping stations, 4 tidal ports, 335 aqueducts (Comerford, 2016; CRT, 2019) and 72 more reservoirs beyond Toddbrook.

The Canal and River Trust was launched as a charity in July 2012, the first major and flagship transfer of a public body (British Waterways) into the charitable or third sector. State ownership was asserted to limit the network’s ability to adapt and innovate. A new civil society organisation was established, believed to unlock the full potential of the waterways to thrive in the future and increase the role of local communities in helping to decide how their local canal or river is run (Defra, 2011). A ‘steering’ state can indeed enable communities to generate beneficial outcomes that are beyond the reach of government alone. But as Rolfe (2017) stresses, the Government rhetoric surrounding localism focuses largely on the devolution of power, with less frequent mentions of the responsibilities, risk and financial liabilities that come with these opportunities.

Growing vulnerability of inland navigation to extreme events

A huge volume of water had poured down through the Derbyshire Peak District hills swelling the Toddbrook reservoir’s water level to the dam’s crest on August 1^st, then cascading onto the concrete spillway (Heidarzadeh, 2019). Concrete spillways are ordinarily designed to allow a safe and controlled release of excessive flood waters and protect otherwise vulnerable earthfill dams, but on this occasion it started to erode and collapse under the torrent of water (ibid). Installed in 1969, the 50 year old ‘thin grey line of concrete’ protecting the town of Whaley Bridge had reached the end of its life (Heidarzadeh, 2019). If the dam burst, 1.22 megalitres of water from the reservoir had threatened to engulf over 400 homes and businesses in parts of Whaley Bridge 0.5km below, and other areas downstream along the River Goyt, under as much as two metres of water (Pidd et al., 2019).

Water rushing down the Toddbrook dam spillway prior to the evacuation of Whaley Bridge. Photo credit: David Lee.

Toddbrook Reservoir, built in 1831, has now been discussed in the global context of ageing dams not designed for ever more extreme rainfall, already unsafe and in need of upgrading (Le Page, 2019). Brooke (2014) has already detailed how Britain’s inland navigation is particularly vulnerable to extreme events, being less able to accommodate the effects of climate change as the network relies on older infrastructure designed for pre-climate change conditions. Embankments may be overtopped more frequently or damaged by high flows; piling or other forms of bank protection may be more susceptible to washing out and to erosion. Low flows can also cause serious implications for the structural integrity of navigation infrastructure, due mainly to the removal of hydraulic support from the waterside face (Brooke, 2014). Brooke concludes climate change could prove costly as inland navigation authorities are likely to have to replace, upgrade or retrofit infrastructure, particularly when the historically low investment levels in much of the inland waterway network are also taken into account (ibid).

Our ‘heritage’ and ‘amenity’ also means ageing infrastructure

British Waterways had been carrying risks related to the condition of ageing infrastructure for many years prior to its charitisation (Lloyd et al., 2009). A report commissioned from KPMG (2008) estimated there was a funding gap of at least £29m per annum between British Waterways’ income stream and the cost of maintaining and preventing further deterioration of the two hundred year old waterways and network assets waterways (including reservoirs, locks, bridges, embankments, aqueducts and cuttings) (in Lloyd et al., 2009). If the British Waterways network was retained in the public sector, the proportion of its navigation assets in poor or very poor condition was projected to almost double by the middle of the next decade, creating a major backlog of repairs and safety maintenance (ibid, 2009). Such a trajectory was thought to create “very substantial and ever-increasing risks to public safety, as well as to the long-term amenity benefits that the waterways bring” (ibid, 2009, p20).

British Waterways was experiencing regular failures of its embankments, with a total of 51 breaches experienced between 2000 and 2009. In 2009, following the global financial crisis, further efficiency savings were announced by the Government, including a cut of another £10m from British Waterways’ existing grant of £57.5m. The Inland Waterways Association stated that the proposed cuts would exacerbate an already critical situation (ibid, 2009).

A devolution of responsibility, risk and financial liability…..

The major driver for the Government’s transfer of British Waterways’ to a charity was to provide new freedoms and strong incentives to bring in new revenue streams, including legacies and donations to fund the operation and maintenance of the waterways. Along with notions of supporting localism and enabling closer involvement of communities, the Government stated key investment objectives were: to foster Canal and River Trust’s increasing self-reliance; to move the long term cost of maintenance from the public sector to civil society and the avoidance of additional unpredictable costs to taxpayers (Lloyd et al., 2009). The Funding Agreement was also said to avoid the most significant risks of an underfunded network in which health and safety risks increased as assets deteriorated and were susceptible to failure (Defra, 2012a).

Defra detailed the grant funding over a 15-year contract to March 2027: a core grant from 2012/13, £39m p.a. index linked on a three-yearly cycle from 2015/16, conditional funding from 2015/16, £10m p.a. not index-linked and reduced gradually over the last five years of the contract to a minimum of £4m (Defra, 2015). There were immediate concerns expressed regarding the adequacy of the proposed funding package from Government and that the projections of voluntary income were over optimistic in the light of the current economic climate (Defra, 2012a, p13). Amendments may be proposed for mutual consideration whenever either party considers this necessary but Defra is under no obligation to increase the amount or to extend the Grant beyond the end of the term (Defra, 2012b). A review will take place in 2021 to 2022 to examine the public benefit case for the Government’s funding of the waterways, also stated to include a consideration of any unintended consequences and whether government intervention is still required going forward (Defra, 2015).

…..or continued shared responsibility for Whaley Bridge and any other communities at risk?

In 2012, the Canal and River Trust took on the responsibility of the heritage assets of British Waterways in England and Wales. The Canal and River Trust also took on the growing liabilities and risk of serious breaches and potential flood risk from British Waterways and the taxpayers in England and Wales. Evidence from other studies of ‘localism’ initiatives have suggested that the language of devolving power has been a false carrot from government, tempting communities to take on greater responsibilities for tackling social issues, but deliberately devolving risk and outsourcing blame (Rolfe, 2017).

Meanwhile, the Canal and River Trust report that independent experts have been appointed to carry out the investigation into what caused the damage to the Toddbrook dam spillway.

We are navigating unchartered governance waters. Will it be all hands on deck for civil society, a blame game and Canal and River Trust cut adrift, or will we see the Government firmly at the helm, retaining responsibility for the future of our communities potentially at risk from climate change?

Photographs courtesy of David Lee.

References:

British Waterways (2008), British Waterways Status Options Review (Report by Consultants KPMG, June 2008).

Brooke, J. (2014) ‘Working Technical Paper Transport: Inland Waterways, Ports and Marine Infrastructure’.  Available at: https://nerc.ukri.org/research/partnerships/ride/lwec/report-cards/infrastructure-source03/ (Accessed: 30 August 2019).

Broomhead, M. (2019) ‘Toddbrook Reservoir owners move to reassure Whaley Bridge residents after heavy rain’, Buxton Advertiser, 17 August.  Available at: https://www.buxtonadvertiser.co.uk/news/toddbrook-reservoir-owners-move-to-reassure-whaley-bridge-residents-after-heavy-rain-1-9941490 (Accessed: 30 August 2019).

Canal & River Trust (2018) ‘About us’, Canal & River Trust. Available at: https://canalrivertrust.org.uk/about-us (Accessed: 30 August 2019).

Comerford, A. (2016) ‘Climate change resilience for inland waterways – the Canal & River Trust approach’ [PowerPoint presentation] Available at:  http://www.pianc.org.uk/documents/seminars/07Mar16/07Mar16-PIANC-Adam-Comerford.pdf (Accessed: 30 August 2019).

Defra (2011) ‘Summary of responses to the consultation ‘A New Era for the Waterways’, 30th March – 30th June 2011’.  Available at: http://www.legislation.gov.uk/uksi/2012/1659/pdfs/uksiod_20121659_en.pdf (Accessed: 30 August 2019).

Defra (2012a) ‘Grant agreement between the Secretary of State for Environment, Food and Rural Affairs and Canal & River Trust’ Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/183235/Canal-rivers-grant-agreement.pdf (Accessed: 30 August 2019).

Defra (2012b) ‘The Secretary of State for Environment, Food and Rural Affairs and Canal & River Trust Memorandum of Understanding’.  Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/183230/Canal-rivers-MOU.pdf (Accessed: 30 August 2019).

Defra (2015) ‘2010 to 2015 government policy: access to the countryside. Appendix 2: funding the Canal & River Trust’. Available at: https://www.gov.uk/government/publications/2010-to-2015-government-policy-access-to-the-countryside/2010-to-2015-government-policy-access-to-the-countryside#appendix-2-funding-the-canal–river-trust (Accessed: 30 August 2019).

Defra, EA and The Rt Hon Theresa Villiers (2019) ‘Environment Secretary Theresa Villiers visits Whaley Bridge’, [Press Release]. Available at: https://www.gov.uk/government/news/environment-secretary-theresa-villiers-visits-whaley-bridge (Accessed: 30 August 2019).

Heidarzadeh, M. (2019) Whaley Bridge dam collapse is a wake-up call: concrete infrastructure will not last forever without care. The Conversation, 5th August 2019. https://theconversation.com/whaley-bridge-dam-collapse-is-a-wake-up-call-concrete-infrastructure-will-not-last-forever-without-care-121423 (Accessed 30th August 2019).

HC Deb (03 September 2019) vol. 664. Available at: https://hansard.parliament.uk/commons/2019-09-03/debates/19090310000012/SummerFloodingAndReservoirReview  (Accessed: 17 September 2019).

Jowitt, R. (2019) ‘Toddbrook Reservoir update’. Canal and River Trust, 28 August.  Available at: https://canalrivertrust.org.uk/news-and-views/news/toddbrook-reservoir-update (Accessed: 30 August 2019).

Parveen, N. (2019) ‘The dam very nearly went’: the scramble to save Whaley Bridge’. The Guardian, 5 August. Available at: https://www.theguardian.com/uk-news/2019/aug/01/uk-weather-homes-evacuated-floods-hit-north-of-england (Accessed: 5 August 2019).

Pidd, H., Gayle, D. and Greenfield, P. (2019) ‘Peak District town evacuated as dam threatens to burst’, The Guardian, 2 August.  Available at: https://www.theguardian.com/uk-news/2019/aug/01/uk-weather-homes-evacuated-floods-hit-north-of-england (Accessed: 30 August 2019).

Weaver, M. and Laville, S. (2019) ‘Whaley Bridge dam: heed flood defence warning, experts urge’. The Guardian, 2 August.  Available at: https://www.theguardian.com/environment/2019/aug/02/heed-flood-defence-warning-from-whaley-bridge-dam-scare-experts-urge (Accessed: 30 August 2019).

Le Page, M. (2019) ‘The world’s ageing dams are not built for ever more extreme weather’.  New Scientist, 2 August. Available at: https://www.newscientist.com/article/2212427-the-worlds-ageing-dams-are-not-built-for-ever-more-extreme-weather/#ixzz5y6Y6ykgF (Accessed: 30 August 2019).

Lloyd, S., Hudson, M. and Bennett, M. (2009) ‘Setting a new course Britain’s waterways in the third sector’, British Waterways, November 2009.  Available at: https://www.compasspartnership.co.uk/pdf/BWSNC.pdf

Rolfe, S. (2017) ‘Governance and Governmentality in Community Participation: The Shifting Sands of Power, Responsibility and Risk’. Social Policy and Society, 17, 579-598.

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Leon Kapetas (University of Cambridge) and Vladimir Krivtsov (Heriot-Watt University) present their highlights of the 2^nd International Conference on Natural Hazards & Infrastructure (ICONHIC2019) and post-conference tour of Knossos and its ancient water management system.

The conference

The Urban Flood Resilience Consortium had the opportunity to present some of their ongoing research at the ICONHIC2019, held in Crete, Greece (June 2019).

The conference attracted a very diverse crowd from academia and industry covering a wide range of problems, from geotechnical failures to coastal and pluvial flooding. The conference kicked off with the inspiring Plenary Lecture delivered by the President of the American Society of Civil Engineers (ASCE), Robin Kemper, on “America’s infrastructure report card: causes, costs, and solutions”.

Leon Kapetas chaired the session on “Ecosystem-based Adaptation for Urban Flood Resilience” which received papers on related modelling applications, water quality studies, urban planning and multi-functionality of infrastructure among others. Four papers from the Urban Flood Resilience project were presented:

Scott Arthur (Heriot-Watt University) presented part of the research carried out under Work Package (WP) 1 on the “Impact of blue/green and grey infrastructure interventions on natural capital in urban development”.

Vladimir Krivtsov presented two papers on “Retrofitting SUDS at Industrial Premises” (WP1) and “Monitoring and Modelling SUDS Retention Ponds: Case Studies from Scotland” (WP2).

Kim Vercruysse (Cranfield University) presented her research under the project’s WP3 with the paper “Developing a spatial analysis framework to guide interoperable urban flood management“.

The papers can be downloaded from the links above or from our website.

The Knossos archaeological site, Heraklion area, Chania, Greece. Visited by ICONHIC delegates interested in ancient water management Source: Vasiahotels.gr.

And the post-conference

The ICONHIC post-conference tour was organised to the Knossos archaeological site and a museum in Heraklion area. This excursion proved to be truly excellent and featured an introduction to the Minoan civilisation which thrived on Crete around 1700 years BC. It was absolutely fascinating to learn that the ancient Greeks had a very sophisticated water management system featuring cisterns, wells and aqueducts allocated to three separate circuits (potable water supply, sewer, and stormwater drainage).

The remains of ancient pipes were the absolute highlight. Pipes were made of clay and consisted of sections screwed into each other, and according to Wikipedia, some of those pipes were deliberately constructed of more porous material, and used for pre-treatment of potable water.  It appears that the issues of water security, flood resilience, and water quality benefits were already high on human agenda as far back as at least 3700 years ago! All in all, amazing stuff and highly relevant to the Blue-Green Cites and Urban Flood Resilience research projects.

—

For the very interested:

Douglas, I. (2013) Cities: An Environmental History, p. 16, I.B. Tauris: London and New York.

Rose, J.B. and Angelakis, A. N. (2014). Evolution of Sanitation and Wastewater Technologies through the Centuries. London: IWA Publishing.

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The Ministry of Housing, Communities and Local Government’s (MHCLG) review of current planning policy for sustainable drainage (SuDS) was published in August 2018. Could this exercise have more to do with validating the Government’s current policy approach, rather than an accurate review of the application and effectiveness of planning policy for sustainable drainage systems? Tudor Vilcan (The Open University) explores in this blog.

Introduction

In England, sustainable drainage systems (SuDS) are still implemented through the planning system, for which policy was strengthened in 2015 to make SuDS a requirement in all new major developments and encourage greater uptake. The MHCLG review provided the opportunity to gauge how the new policy is being implemented (p4). As the original intentions of Schedule 3 of the Flood and Water Management Act (FWMA) 2010 were to make the requirement for SuDS mandatory on new developments, complying with new National Standards on SuDS (which would have set out how drainage systems should be designed, constructed and maintained), then a comprehensive and critical assessment of the performance of current policy is vitally important in terms of policy design.

The National Planning Policy Framework (NPPF) (DCLG, 2012) expects local planning authorities, when determining planning applications, to ensure that sustainable drainage is prioritised in areas at risk of flooding, to conserve and enhance biodiversity, and, adopt strategies to mitigate and adapt to climate change. The review examined the extent to which national and local planning policy has been successful in encouraging the uptake of SuDS in new developments, examining how national planning policies for SuDS are reflected in local plans and the uptake of SuDS in major and minor new housing developments and commercial/mixed-use developments (MHCLG, 2018, p5).

The report suggests that SuDS are implemented at rates of 80 to 90% in England. It also states that more than 80% of the adopted local plans contained policies reflecting the requirements of the 2012 National Planning Policy Framework. As the report is very brief in describing its methodology, we sent a Freedom of Information (FOI) request to find out more. We find the report’s findings to be problematic in three key areas.

1. The nature of SuDS?

The FOI states that ‘a specific definition for SuDS was not employed in order to avoid ruling out any novel applications’. The report provides an indication as to what was actually counted as a SuDS feature, in that it makes an inventory of the range of SuDS technologies and features found in the planning applications: ‘ponds and attenuation basins, green roofs, permeable paving, tanks, swales and soakaways and frequently involved combinations of one or more of these components’ (MHCLG, 2018, p. 8, emphasis added).

Although DEFRA’s non-statutory standards (DEFRA, 2015) classify tanks as SuDS, in The SuDS Manual (CIRIA, 2015), attenuation storage tanks (which also include oversized pipes, geocellular storage and vortex flow control systems) are described as a ‘below-ground void space for the temporary storage of surface water before infiltration, controlled released and use’ (Ballard-Woods et. al, 2015, p. 437). They only have a flow control function (relating to water quantity), but any drainage system located below ground misses on all the other benefits of SuDS (such as water quality, amenity and biodiversity). Of further concern, only ‘generally’ were ‘‘traditional’ drains and sewers, gullies and catchment pits identified by LPA (Local Planning Authorities) and LLFA (Lead Local Flood Authorities) officials as falling outside the scope of acceptable SuDS’ (MHCLG, 2018, p. 10). In addition, ‘heavily engineered components involving such elements as excessive amounts of concrete, pumping systems, underground storage tanks and connections to main drains, or elements that were difficult to access or maintain were also viewed unfavourably’ (ibid) – hence we are concerned that in the absence of a specific definition, which components were counted as SuDS in the 80%.

The Big SuDS Survey

In The Big SuDS Survey, around 30% of all SuDS contained such systems (attenuation storage tanks and proprietary treatment systems that included vortex flow devices). The qualitative answers in the Big SuDS Survey suggested that ‘we would class oversized pipes, storage tanks and vortex flow control devices as surface water management tools rather than SuDS’ (Melville-Shreeve et al, 2018, p. 15). The Landscape Institute report on achieving sustainable drainage has also found that councils feel constrained by Defra’s Non-Statutory technical standards: ‘they do not see tanks and large pipes as sustainable but find them difficult to challenge as they cannot refuse them if they deal with quantity’ (Landscape Institute, 2019, p. 11). In brownfield development, where the natural hydrology of the site is compromised, tanks might get approved as a way of addressing flow control. But there is a risk that they will tick the SuDS box, when in reality, green SuDS can be implemented as well.

Multiple Benefits

The MHCLG report itself states that SuDS can also provide additional benefits such as removing pollutants from urban run-off and combining water management with green space that offers scope for recreation and wildlife’ (MHCLG, 2018, p 4). Hence, if we are referring to SuDS according to this definition to include multiple benefits, then SuDS would need to be counted differently and that is likely to impact the reported uptake rates. The question remaining unanswered here relates to the nature of SuDS and the emphasis we put through planning on the meaning of sustainability. Or as the Landscape Institute report asks; ‘is this sustainable drainage, or just drainage?’ (Landscape Institute, 2019, p. 4).

2. Methodology: representativeness and robustness

The MHCLG report uses what is called a nested design, where the researchers first selected a number of LPAs, and them sampled a series of planning applications from the selected LPAs.

12 LPAs were selected out of the total of 338 in England, ‘selected by listing all 338 LPAs by land value estimates, dividing the LPAs into twelve groups, then using the average land value for all LPAs within each group to identify the LPA with land value closest to the average in each group’ (MHCLG, 2018, p. 5). For the sampling strategy used for selecting the planning applications where SuDS were counted (in the 12 LPAs selected), ‘evidence was collected through analysis of a range of approved planning applications (minor residential, major residential and commercial/mixed-use developments) spanning the period 2012-16’.  From the FOI request, we also understood that the strategy selects one application for each type of development for four distinct periods of time (post 2012, in flood risk areas and non-flood risk areas and post 2015 (June to December 2015 and post 2016)). This means that there were 13 (for one category it requests 2 applications instead of 1) applications selected for each LPA, with a total of 156 applications.

From a statistical point of view, the design is therefore not probabilistic, meaning that none of the choices (of either LPAs or planning applications) have been random. The 156 applications also represents a very small sample size in comparison to the overall number of planning applications. The combination of a non-probabilistic design and small sample size means we do not have a mechanism in place to estimate uncertainty (using statistical probability theorems), that is, to provide an indication of the reliability of a measurement. This ultimately means that the report’s finding that 80% of planning applications have SuDS could have a variability of +5 % or -50%. Notably, The Big SuDS Survey put the uptake of SuDS at around 40% (Grant et al., 2017) and the more recent report from the Landscape Institute found that only ‘3% of authorities reported receiving adequate information to assess a planning application’ (Landscape Institute, 2019, p. 5). For these reasons we remain somewhat sceptical regarding the uptake rates of SuDS reported by MHCLG (2018).

3. Critical interpretation of data (or lack therefore of)

A major issue permeating the report relates to the manner in which the data is interpreted. We pull out just a few examples. The report states that when SuDS did not feature in an application, ‘drainage of surface water to a water body was often described in such a way that could be interpreted as sustainable’ (p. 8). This is clearly problematic, because simply discharging to a body of water does not necessarily bring with it the same benefits as SuDS, especially if this is through gullies or pipes and fails to provide flow attenuation and infiltration, not to mention the wider array of multiple benefits.

We feel the conclusions on post-construction checks and proper functioning of SuDS are also based on imperfect premises. Interviews with members of the LPAs highlight that they lack regimes and resources for ensuring that SuDS have been constructed as designed and agreed on. The majority of LPAs have to proceed via a reactive rather than proactive approach towards the issue, essentially reliant on receiving complaints about SuDS malfunctioning. Rather than reflecting and responding to the implications of such a major issue, the report states that they were not provided with an example of a failed scheme by the sampled LPAs, and in the two cases of unsatisfactory performance, the issue was resolved quickly (p11). This appears at odds with the findings of the interviews presented above; if there are few to zero post-construction checks performed, then how are we to know whether other schemes are faulty or not to date? These are only likely to manifest during a flood event and many SuDS components might take some time to exhibit symptoms of malfunctioning over their decades’ long lifespan. The performance of SuDS could remain a loaded gun issue.

Conclusions

The question of the effectiveness of the ‘strengthened’ planning system to implement SuDS in England is a vital one considering the importance of SuDS in the management of surface water flooding and adaptation to the effects of environmental change. MHCLG’s report represented an opportunity to provide a comprehensive and critical assessment of the performance of current policy. We do not conclude that the MHCLG review has ‘shown that current arrangements for SuDS in planning has been successful in encouraging the take-up of sustainable drainage systems in a cross-section of new developments with almost 90% of all approved planning applications sampled featuring SuDS’ (p12). However, firstly and fundamentally, we are concerned as to what is considered to constitute a SuDS feature. Second, the methodology raises questions in relation to the representativeness and robustness of the report’s findings. Although MHCLG does acknowledge that there is potential for industry bodies to address skills and knowledge gaps, and that more emphasis by applicants is required on SuDS adoption and maintenance arrangements (p12) there is an overarching tendency in the report towards a lack of genuine engagement and critical reflection in the interpretation of data. The recommendations of this report would appear to have influenced the latest version of the NPPF (2018), for which we are concerned will not offer the substantial improvement and support to stakeholders required when it comes to the future uptake of sustainable drainage and its maintenance in England.

Please contact Tudor Vilcan (tudorel.vilcan@open.ac.uk) for more information or to share your thoughts.

References

DCLG (2012) National Planning Policy Framework. Available at: http://webarchive.nationalarchives.gov.uk/20180608095821tf_/https://www.gov.uk/government/publications/national-planning-policy-framework–2. Accessed (15.01.18).

DCLG (2018) National Planning Policy Framework. Available at https://www.gov.uk/government/publications/national-planning-policy-framework–2. Accessed (15.01.18).

DEFRA (2015) Non-statutory Technical Standards for Sustainable Drainage Systems. March 2015. Report PB14308. Dept. Environment & Rural Affairs (DEFRA), London. UK.

Grant, L., Chisholm, A., and Benwell, R., 2017. A place for SuDS? Assessing the effectiveness of delivering multifunctional sustainable drainage.  The Chartered Institution of Water and Environmental Management. London, UK.

Landscape Institute, 2019. Achieving sustainable drainage. A review of delivery by Lead Local Flood Authorities, (online) available at https://www.landscapeinstitute.org/wp-content/uploads/2019/01/11689_LI_SuDS-Report_v4a-Web.pdf.

Melville-Shreeve, P., Cotterill, S., Grant, L., Arahuetes, A., Stovin, V., Farmani R., and Butler, D. (2018) State of SuDS delivery in the United Kingdom. Water and Environment Journal, 32, 9–16.

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On 7^th March 2019, the Urban Flood Resilience consortium and partners in Newcastle showcased progress with the implementation of Blue-Green Infrastructure (BGI) and shared key findings from the interdisciplinary research project. The 2019 Newcastle Blue and Green Declaration was launched, committing signatories to greater use of multifunctional BGI in projects and piloting new ways of working to realise the multiple benefits.

The event was organised into two sessions. Sangaralingam Ahilan summarises the key points.

Morning session 1

Cllr Nick Kemp (Newcastle City Council) opened the event, emphasising Newcastle City Council’s commitments to increasing the amount of blue and green in Newcastle to tackle flood risk and climate change, and to bring wider social, economic and environmental benefits to the city.

Colin Thorne (University of Nottingham, principal investigator for the Blue-Green Cities and Urban Flood Resilience projects), discussed Our Journey along the Blue-Green Path to Urban Flood Resilience. Colin set the scene by introducing the themes of the two projects and emphasised that transformative change in planning, design and implementation would be required to promote adaptation of green infrastructures in urban water management.

Richard Warneford (Northumbrian Water) and Leila Huntington (Environment Agency) jointly delivered a talk on The Opportunities and Challenges for partnership delivery of Blue Green Infrastructure. They outlined the core objectives of their organisations with regards to sustainable drainage and BGI and demonstrated how they had met some of their mutual objectives through the Northumbria Integrated Drainage Partnership. The partnership enabled the cost-effective implementation of several exemplar BGI schemes in Newcastle, e.g.  Brunton Park, Killingworth & Longbenton.

Justin Abbott (Arup) presented on Cities, Water, Resilience, and the Circular Economy, stressing that progress on sustainable water and sanitation would be impossible without progress on the other Sustainable Development Goals, e.g. sustainable cities and communities, climate action, life below water. Justin explored systems-thinking, the circular economy, digital technologies and holistic urban planning to achieve a resilient urban water environment.

James Harries (RTPI) discussed Boosting multi-functional BGI through the planning system, outlining several successful initiatives of incorporating green infrastructure into city and national urban planning policies. He stressed the importance of achieving integrated infrastructure planning through lobbying, training and advice, and highlighted gaps within planning policy and guidance, narrow technical standards and uncertainty about long-term management, which can considerably limit the likelihood of BGI adaptation in cities.

Fola Ogunyoye (Royal HaskoningDHV) talked about Delivering urban flood resilience using blue-green approaches, exploring the impact of flooding and drought on quality of life and the economy.  Fola discussed how we could change the mindset from ‘making things less bad to making things better’ and presented projects on the adaptation of BGI to manage both normal and extreme events in the UK, Netherlands and Mexico.

Slide from Ogunyoye’s presentations on urban flood resilience

Slide from Warneford and Huntington’s presentation on the Killingworth and Longbenton project

Morning session 2

Eugene Milne (Newcastle City Council) shared A public health perspective on BGI, opening with the direct and indirect health risks of flooding in England. He then shared national and international research findings on how access to green and open spaces positively impact on health. He finished by outlining how green infrastructures may reduce particulate matter in the urban environment.

Iain Garfield (Newcastle University) outlined Newcastle University’s approach to flood management, showing how Newcastle University and regional partners acted upon on the 2016 Newcastle Blue and Green Declaration. He shows examples of BGI adaptation in Newcastle Helix and Richardson Road. He his talk by quoting Henry Ford “Coming together is a beginning, staying together is progress, and working together is the success.”

Ola Holmstrom (Sweco) introduced a Nordic perspective to BGI. He began by showing the impact of the 2011 and 2012 floods in Sweden. He then outlined how Stockholm had integrated urban green infrastructure and ecosystem service into the new city plan to cater for public access to green spaces and to cope with extreme weather events.

Lisa Stephenson (Groundwork NE & Cumbria) discussed Partners and Participation: regional examples of BGI, illustrating three case studies: the Ouseburn, Wyke Beck and the Tyne Estuary, all delivered in partnership. Lisa stressed that the multi-agency partnership was more than a sum of its parts and attracted varied funding options.

Gwen Rhodes (Stantec) talked about Community-based SuDS, showing successful adaptation of a number of sustainable urban drainage systems in Whitburn Spills, Roker Park SuDS and Moorlands School, Manchester.

Signatories of the 2019 Newcastle Blue and Green Declaration (the morning presenters)

Afternoon session – Stream 1:  research project dissemination

Emily O’Donnell (University of Nottingham) opened the session by introducing her research into hidden perceptions of SuDS through Implicit Association Tests. She highlighted the importance of investigating subconscious perceptions (alongside standard stated preference tests such as questionnaires) to truly understand people’s attitudes towards BGI.

David Butler and Sangaralingam Ahilan (University of Exeter) discussed a move from Rainwater harvesting to rainwater management systems. David introduced the evolution from single-purpose rainwater harvesting (water supply only) to multi-purpose rainwater management (water supply and flood resilience). Ahilan shared simulation results on the potential impact of household rainwater management on water supply and flood resilience in Newcastle and Exeter.

Stephen Birkinshaw (Newcastle University) presented on Flood modelling of Newcastle: getting the pipes and infiltration right. Steve explored how we could realistically account for urban green areas, soil moisture and rainfall losses in sewer networks in hydro-system modelling. He compared traditional methods with proposed refined methods. Steve stressed that “good models and good modellers should aim for the right results for the right reasons”.

Glyn Everett (University of the West of England) explored BGI Community Engagement (BGI-CE), using three Bristol case-studies. Glyn spoke of the need for deeper and longer-term BGI-CE. He stated that BGI-CE should listen to, and learn from, communities, giving them some voice and control in design decisions to improve felt ‘ownership’. This may hopefully improve general behaviour, and encourage more lay-stewardship.

Slide from Vercruysse and Dawson’s presentation on interoperability

Silde from O’Donnell’s presentation on implicit perceptions of SuDS

Afternoon session – Stream 2: research project dissemination

Kim Vercruysse and David Dawson (University of Leeds) examined Interoperable flood management in Newcastle: exploring needs, opportunities and challenges. They introduced a spatial analysis framework developed to prioritize locations for flood management and identifying opportunities for interoperable adaptation solutions. By aligning data on flood dynamics with data on infrastructure systems, the framework aims to enable strategic combination of investments in transport, housing, land-use and water management.

Vladimir Krivtsov (Heriot-Watt University) introduced Retrofitting, monitoring and modelling SuDS. He explored the retrofitting of SuDS at Houston Industrial Estate, Edinburgh, sharing survey findings concerning the estate’s companies’ familiarity with different SuDS options. He also outlined the impact of Eliburn and Appleton stormwater ponds on water quality, suspended sediments and ecosystem functioning.

Leon Kapetas (University of Cambridge) discussed an adaptation pathways approach to deliver multiple benefits of BGI in an uncertain future. He explored how to identify the right mix of Blue-Green and Grey infrastructure to address future changes in climate and urbanisation. Leon also discussed the inherent uncertainty in developing flexible pathways and the need to account for multiple benefits.

Tudor Vilcan and Karen Potter (Open University) explored Implementing SuDS through the planning system, discussing the challenges and opportunities. They also examined different SuDS policy arrangements in England and Wales and the effect of the SuDS policy choices on the likelihood of SuDS uptake.

Final plenary

The final session, chaired by Emily O’Donnell and Tudor Vilcan, discussed Developing and implementing Blue-Green visions through Learning and Action Alliances’ (LAAs). Darren Varley (Newcastle City Council) and Louise Petrie (Newcastle University) shared their experiences of the Newcastle LAA, which mainly explores the potential opportunities of retrofitting Blue-Green systems in the city. Simon Harrison (Ebbsfleet Development Corporation) and Paul Kent (Southern Water) spoke about the Ebbsfleet LAA, which is investigating sustainable water use options, wherein a system dynamics model has been being developed.

Read more about the dissemination event and Newcastle Declaration on our website.

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In this blog Stephen Birkinshaw (Newcastle University) discusses flood inundation and urban water modelling.

As part of the Urban Flood Resilience project, I have been carrying out modelling using the CityCat urban flood model. The model produces space-time maps of flood depths and flow pathways. But it is important not to just model in isolation, there is a need to understand what is really happening on the ground.

For most areas of the UK there are accurate and fine resolution surface elevation data (from LiDAR) together with OS MasterMap data which provides buildings and green area data. But the subsurface data is much harder to obtain and less accurate. Ideally there would be perfect information on the location and sizes of all the sewers and all the culverted rivers. But often this information is not available so it takes a bit of detective work to find out what is happening.

Granton Ponds, Edinburgh

An example of this sort of detective work can be considered for the Granton Ponds in Edinburgh. These ponds have been constructed to help reduce urban flooding that has been exacerbated by the expansion of impervious area. Before visiting the site, I carried out a CityCat simulation for a short duration extreme event for the area around the ponds. In Figure 1, the Granton Ponds are located near the north east, increased water depths are shown as darker blue and the red arrows indicate flow velocity. Water from a catchment area of around 0.9km² drains into and through the eastern pond.

On 23^rd November 2018 I visited the site with Vladimir Krivtsov (Heriot-Watt University). Site visits are really important to understand what is happening and together we carried out an in-depth observational assessment to ground-truth the remote sensing information and the initial understanding of the  CityCat results. Water quality measurements were being carried out in the western pond and this pond (Figure 2) has good water quality. It was clear the ‘eastern pond’ has a much higher flow rate, and is actually more like a wetland than a pond and it seemed much more polluted.  Around both ponds it was nicely landscaped and it was great to see this Sustainable Urban Drainage feature within the urban environment.

Figure 1 CityCat Simulation of the Granton Ponds for a short duration extreme event. Water depths are shown in blue and velocity vectors in red (© Google maps)

Figure 2 Granton Western Pond, Edinburgh

What was not clear was where the water draining into the ponds came from or even when the ponds were built. A quick search found some details of the scheme. It says that “Caroline Burn, a culverted water course, which crosses the site eventually draining into the estuary, is redirected to emerge as a water feature at the centre of the park to run westward [sic] along the park to an outflow embedded at the edge of the new square”.

I then found more information by looking at two of my favourite resources.

Google Earth

Firstly, historical aerial images from Google Earth. Figure 3 shows three images. In 2003 only the eastern pond was built. With the inflow from the culverted Caroline Burn visible at the western edge of this pond. By 2005 the western pond had also been built and by 2016 the whole area had been nicely landscaped. The pond on the south-west corner of these images is an old quarry, which was also turned into a haven for wildlife.

Historical and aerial maps

Secondly, georeferenced historical and aerial maps that can be seen next to each other on the National Library of Scotland website. From the OS Six Inch 1988-1913 map (Figure 4) it is possible to see some of the course of the Caroline Burn (which I have highlighted). From the 1937-1961 map some of the course can still be seen but much of the burn has been culverted under a housing estate and also the gas works. The redirected burn can be seen as the dashed red line on the recent aerial image. What is interesting is how the course of the culverted burn is followed very closely by the CityCat flow paths (Figure 1). This regularly happens in CityCat simulations in urban catchments. Unfortunately this still leaves some questions.

Q. How much flow can Caroline Burn take before flooding and mow much rainfall is needed to make it flood?

Q. What is the source of water to the western Granton Pond?

It appears to be surface water drainage from the new housing estate to the south and west of the pond. But we really need a sewer map to find out.

Figure 3 Google Earth Aerial images of the Granton Ponds

Figure 4 Old OS maps and an aerial image from maps.nls.uk. Maps are overlaid with the course of the Caroline Burn.

A final interesting fact is that water from Caroline or Granton Burn was stored in a pond behind Caroline Park and used to supply water to a factory to make ice (the most modern of its kind in 1952) for the fishing industries.

Detective work is required to understand flood issues in urban areas. Historical maps and documents provide a wealth of information on the evolution of the urban environment. This enables better flood risk estimation, benefitting communities.

Learn more about Steve’s research in WP1 and WP2, Urban Flood Resilience research project.

The post The Urban Water Detective – Where is the Water Flowing? appeared first on Blue-Green Cities.

In this blog, Glyn Everett presents and reflects on the ethics of care shown by some local users and residents towards blue-green spaces (primarily designed to manage flood risk), and how this can help increase a variety of multiple benefits.

Introduction

I have been spending time with interested groups around two of our (Urban Flood Resilience research project) study sites in Bristol. These are open green spaces, with retention ponds, designed to reduce the risk of flooding elsewhere. As such, they do not affect flood risk in their local vicinity and awareness of purpose and functions is, rightly or wrongly, very low. Chatting with local people, I have regularly encountered incredulity or disbelief when I have suggested that the areas were designed to reduce flood risk in other parts of the city. Why should anyone believe me? There is no clear evidential link, simply open green and blue spaces – for aesthetics and leisure, they might very reasonably presume.

Unfortunately, it might also help explain why some treat these spaces with so little regard. It is not that they are badly treated, for the most part, but rather that the hard paths through them are used merely as convenient routes of transit, rather than the areas being more appreciated and valued. To this end, fewer people might ‘care’ for them, leaving them open to potential mistreatment and lesser ‘multiple benefits’.

It therefore feels very positive when we see groups of residents and users who begin to take some ‘ownership’ (formal or informal) of these spaces, either to reshape them slightly to offer improved amenity, or simply contributing to the upkeep.

Site 1

Site 1 is a green space next to a modern housing development built with a concern for sustainability. A Residents Group convenes monthly to discuss issues arising, and during my time interacting with them, members have created an Environment Group to think about treatment of the land immediately surrounding the green space that is under their control. They have since spent some weekends clearing and tidying a nearby swale and planting wildflowers in a meadow. Some wildflowers had been planted by the developer, but these had been lost due to the voraciousness of neighbouring grasses. On one day I was with them, they spent as long digging spaces to plant Yellow Rattleweed as they did wildflower plugs. The Rattleweed should then parasitise the grasses and hold them in check, to allow the wildflowers to establish and thrive.

In another nearby area sits a retention pond that has been overtaken by a type of Bulrush, installed by the developer. Being so voracious, it has taken over most of the pond; irrespective of how this may or may not affect the pond’s retention capacity, the Bulrush is a problem for the tadpoles, frogs and other flora and fauna. Biodiversity and amenity are impacted – the pond simply doesn’t look half as attractive. A few lay attempts have been made over the years at clearing the Bulrush, but because these have not cleared down to the roots, it has come back the next year. The group are now seriously considering hiring professional contractors to do an intensive clearance – although given that the funding has not yet been secured and the frogs will soon return to spawn, they may sadly have to wait another year before they can take action.

A retention pond in Bristol

Site 2

Site 2 is a large community park with several retention ponds that are tended and maintained by the Local Authority (LA). Two Friends groups also operate within the area. The first, a more environmentally-oriented group, conduct weekly litter-sweeps and have begun planting a small community orchard. The second operates within a small space to the side of the park that had previously been overgrown and had become a gathering-space for antisocial behaviour (drinking, littering and drug-use).

The first group was brought together in reaction to the LA’s decision to do some quite large-scale clearing and desilting of the ponds; their functionality was being affected by the silt and plant-growth. The group were unaware of the ponds’ flood risk management function and were disturbed by what they saw as the wilful destruction of wildlife habitats. As a result, the group came into being, entered into some productive conversations with the LA and has become a valued LA ally in conducting low-level lay maintenance as well as clearing and planting the orchard.

The second group are more spiritually-oriented; after some conversations with the LA, they took control of the neglected area. Following fundraising efforts and a lot of voluntary work, they have transformed it into a relaxing green-space, with seating and sculptures, hugely improving the amenity offer.

Green space seating and sculptures in Bristol

Awareness of flood risk management function

None of these three groups had any awareness about the spaces’ flood-risk functions before meeting me, and with a couple it took some convincing before they believed such. However, all are actively interested in a number of the further multiple benefits that we argue blue-green infrastructure should provide: the aesthetics of the spaces, habitats for improved biodiversity, offering educational opportunities as well as some local food-cultivation and gathering.

Whilst I began my work with them somewhat concerned about their lack of understanding of flood function, I have since become much more relaxed; so long as their interventions have no negative impacts, they can simply improve the overall offer of multiple benefits. If only more groups could gather to offer similar ethics of care around sustainable drainage systems around the country, ecosystem services assessments would be shifted more strongly toward the benefit over the cost end of the spectrum, and their ‘sustainability’ might be much more assured!

Read more about Glyn Everett’s research on the Urban Flood Resilience Research Project (WP4).

If you enjoyed Glyn’s blog see our earlier blog on how low-cost small-scale blue-green interventions and community led projects may enhance urban flood resilience.

The post Ethics of care towards Blue-Green spaces appeared first on Blue-Green Cities.

In this blog Skhue Ncube introduces her research focus on Blue-Green infrastructure and natural capital as part of the Urban Flood Resilience project.

Introduction

Natural capital and ecosystem services concepts are a popular way of describing the multiple benefits we get from the natural environment. The publication of the Millennium Assessment in 2005 has, along with national publications such the UK National Ecosystem Assessment (2011), raised the profile of these concepts.

Natural capital refers to the stock of natural features/assets, e.g. freshwater, land, soil, minerals, air, seas, habitats, biodiversity and processes which together provide the foundation for the flows of ecosystem services (Guerry et al., 2015; Natural Capital Committee, 2015; Rouquette, 2016) (Figure 1).

Ecosystem services are the flows of benefits such as food, flood regulation, climate regulation and recreational opportunities that people gain from natural ecosystems (Constanza et al., 2017).

Figure. 1. The interaction between built, social, human and natural capital. (Source: Constanza et al., 2017)

Both global and national trends show that natural capital is declining due to human influenced land use changes such as urbanisation and natural resource depletion (Natural Capital Committee, 2015; Holt et al., 2015). Understanding of these concepts have led to an interest in the development of suitable metrics, models, datasets and tools for measurement of natural capital as well as assessing how it is changing over time. The Natural Capital Committee suggests the concept of natural capital be tried in core environmental contexts such as urban settings. Although urban expansion/intensification impacts on natural capital and the multiple benefits available to the urban population, it is recognised that Blue-Green infrastructure (e.g. rain gardens, swales, ponds etc.) can at least reduce these impacts (Hansen and Pauleit, 2014).

Blue-Green multifunctionality

While ecosystem services knowledge is already in use in urban planning, especially the multiple benefits from Blue-Green infrastructure systems (Meerow and Newell, 2017; O’Donnell et al., 2017), there is still need for natural capital assessments at relevant scales to inform planning decisions and outcomes (Cortinovis and Geneletti, 2018). Furthermore, the multifunctionality of Blue-Green infrastructure beyond addressing one main issue such as urban flooding has not been adequately explored and accounted for (Cortinovis and Geneletti, 2018).

Nonetheless, Blue-Green infrastructure are often promoted on their multifunctionality potential compared to grey infrastructure (Hansen and Pauleit, 2014). The multifunctionality of green infrastructure is mostly traded-off for locational/technical/physical factors which influences the multiple benefit areas among urban communities. The question is whether such multiple benefits are located where they are needed the most or located in technically suitable areas.

While the quality and quantity of green infrastructure is important, the Natural Capital Committee also argues that its distribution and equity is of equal importance as it is usually the poor who lack access to good quality green infrastructure and associated multiple benefits.

Research aim and case study area

The aim of this research is twofold;

1. To investigate how different Blue-Green infrastructure investment pathways and future land use change scenarios affect the dynamic evolution of natural capital in the London Borough of Sutton.
2. Compare the technical suitability location of Blue-Green infrastructure to where the multiple benefits from such interventions are needed the most (demand areas) in a locality as identified by local stakeholders.

The case study area in the London Borough of Sutton is primarily a residential area which has significantly expanded over time, with plans to further introduce more housing units in the next three decades. As a result of such growth, the existing drainage network has exceeded its capacity and recent extreme rainfall events have led to increased flooding incidents. To address these challenges, the local authority intends to integrate Blue-Green infrastructure with existing grey infrastructure to reduce the flood risk.

Methodology overview

The natural capital assessment approach for this research is outlined in Figure 2.

Figure 2: Methodology overview.

This study will utilise tools such as the Natural Capital Planning Tool (NCPT) and the Benefits of SuDS Tool (BeST) (CIRIA, 2015) to assess the impact score of proposed developments on natural capital and ecosystem services. A GIS based analysis will be used to evaluate current and future natural capital spatio-temporal changes associated with different Blue-Green infrastructure investment pathways. There is growing interest in using practically applicable analytical tools that link the natural environment and society. A wide range of tools have recently been developed to analyse ecosystem services, natural capital and green infrastructure (see Tool Assessor).

Conclusion

This research focusses on natural capital assessments and opportunities associated with different Blue-Green infrastructure systems for urban resilience and sustainability in light of future uncertainties associated with climate change, demographic changes etc. When undertaken as part of wider environmental assessments, natural capital assessments could ensure that natural capital is considered alongside built, financial, social and human capital in sustainable urban development. Such an assessment could also aid planners and decisions makers to further understand the interdependency between the natural environment, economy and society in the planning process.

Dr Skhue Ncube is a Research Associate at Heriot-Watt University, and part of the Urban Flood Resilience research consortium.   

The source of the figures used in this blog are cited. The featured image is labelled for non-commercial reuse.

References

• CIRIA. 2015.  Benefits of SuDS Tool (BeST). CIRIA, UK.
• Cortinovis C and Geneletti D. 2018. Ecosystem services in urban plans: What is there, and what is still needed for better decisions. Land Use Policy, 298-312.
• Costanza, R., de Groot, R., Braat, L., Kubiszewski, I., Fioramonti, L., Sutton, P., Farber, S. & Grasso, M. 2017. Twenty years of ecosystem services: How far have we come and how far do we still need to go? Ecosystem Services, 28: 1-16.
• Grêt-Regamey, A., Altwegg, J., Sirén, E. A., Van Strien, M. J. & Weibel, B. 2017. Integrating ecosystem services into spatial planning—A spatial decision support tool. Landscape and Urban Planning, 165, 206-219.
• Guerry, A. D., Polasky, S., Lubchenco, J., Chaplin-Kramer, R., Daily, G. C., Griffin, R., Ruckelshaus, M., Bateman, I. J., Duraiappah, A., Elmqvist, T., Feldman, M. W., Folke, C., Hoekstra, J., Kareiva, P. M., Keeler, B. L., Li, S., Mckenzie, E., Ouyang, Z., Reyers, B., Ricketts, T. H., Rockström, J., Tallis, H. & Vira, B. 2015. Natural capital and ecosystem services informing decisions: From promise to practice. Proceedings of the National Academy of Sciences, 112, 7348-7355.
• Hansen, R. & Pauleit, S. 2014. From Multifunctionality to Multiple Ecosystem Services? A Conceptual Framework for Multifunctionality in Green Infrastructure Planning for Urban Areas. Ambio, 43, 516-529.
• Hein L, Bagstad K, Edens B, Obst C, deJong R, Lesschen JP. 2016. Defining Ecosystem Assets for Natural Capital Accounting. PLoS ONE 11(11): e0164460. doi:10.1371/journal. pone.0164460
• Holt, A. R., Mears, M., Maltby, L. & Warren, P. 2015. Understanding spatial patterns in the production of multiple urban ecosystem services. Ecosystem Services, 16, 33-46.
• Lennon, M., & Scott, M. 2014. Delivering ecosystems services via spatial planning: Reviewing the possibilities and implications of a green infrastructure approach. Town Planning Review, 85(5), 563–587.
• Meerow, S., and Newell, J.P. 2017. Spatial Planning for multifunctional green infrastructure: Growing resilience in Detroit. Landscape and Planning, 159, 62-75.
• Millennium Ecosystem Assessment. 2005. Ecosystems and Human Well-being: Synthesis. Washington (DC): Island Press.
• Morgan, M. and Fenner, R. 2017. Spatial evaluation of the multiple benefits of sustainable drainage systems. Proceedings of the Institution of Civil Engineers – Water Management, 0, 1-14.
• Natural Capital Committee. 2015. The state of Natural Capital: Protecting and improving natural capital for prosperity and well-being, Third Report to the Economic Affairs Committee, England.
• Natural Capital Planning Tool. 2018.
• O’Donnell E, Woodhouse R and Thorne C. 2017. Evaluating the multiple benefits of a Newcastle surface water management scheme. Proceedings of the Institution of Civil Engineers – Water Management, http://dx.doi.org/10.1680/jwama.16.00103.
• Rouquette, J.R. 2016. Mapping Natural Capital and Ecosystem Services in the Nene Valley. Report for the Nene Valley NIA Project. Natural Capital Solutions.
• UK National Ecosystem Assessment. 2011. The UK National Ecosystem Assessment Technical Report. Cambridge (UK): UNEP-WCMC.

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