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INTRODUCTION Following increasing environmental concerns and the announcement of the proposed development for the Harrow and Wealdstone Opportunity Area in London, considering the future of Harrow has never been more important. Harrow offers a unique location for alleviating housing pressures in central London. It provides an easy commute into the centre whilst also delivering a more tranquil environment where individuals can feel closer to nature. This connection between humans and nature is becoming increasingly important to understand as environmental concerns bring growing risk the area. The reality of climate change means the UK is likely to experience more intense climates with increased rainfall, hotter summers, and colder winters. Risk from flooding on urban environments is due to increase and continuing with existing policies in urban design is no longer enough. This has been experienced in Harrow with a growing number of flood incidences. These are expected to rise without the introduction of more sustainable urban design. Since flooding cannot be eliminated, adaptation measures need to be taken to manage the risk from these unpredictable weather patterns. These can be integrated within urban design such as increased planting, using permeable paving, and creating flood catchment areas. This can help reduce the effects of climate change by increasing oxygen supply, slowing water runoff, and reducing the energy required to treat water as less water reaches the sewer system. Implementing these measures into the future development of Harrow would help ensure that the area meets the needs of both present and future generations. By addressing this concern of flooding through a sustainable lens, this strategy draws attention to the importance of bringing longevity to the Harrow and Wealdstone Opportunity Area beyond those proposed in the existing plans.
LOCATION Situated to the North-West of central London in the outer borough of Harrow, the Harrow and Wealdstone Opportunity Area sits in an enviable location. It includes part of London’s Green Belt and borders Hertfordshire to the North, whilst also offering direct links into centre of London. This balance between nature and the city make the area highly popular and it experiences wide cultural diversity. As a suburb in the South East of the United Kingdom, the area has a typically warm and temperate climate, with significant rainfall throughout the year. Rainfall often travels fairly rapidly across the contours of the borough as the ground is predominantly a mixture of clay and loamy soil. This type of soil is very dense and subsequently unable to absorb significant quantities of excess water.
Census data Children : 20.4%
London lost rivers
Families : 54.1%
Schools nearby Flood zones
The integration of primary schools is the foundation and the start for the social co-evolutionary behaviour of people. Students’ will be exposed to the important role of ecology from early on where it is integrated as a practical part of their curricula. The curricula of the school years 3 to 6 cover related topics in humanities and science varying from: life cycles of plants and animals to rivers and natural disasters. Therefore, with the help of the Harrow Teaching Schools Alliance (HTSA) in collaboration with UCL’s Institute of Education, these issues could be highlighted in a practical manner. Another scheme that will be initiated, in collaboration with SeedBank and London National Park City, is the seeds that are distributed for free to schools to be planted by students. The practical lessons from a young age in the suggested scheme should evoke the importance of ecology in them and offer them small roles, such as planting plants, to make a difference. The first targeted schools are Pinner Park Junior School, which is an existing member of HTSA, St. Teresa's Catholic Primary School and Nursery and Grim’s Dyke School since they are in close proximity to the chosen sites. This scheme should be developed by time to cover more primary schools around Harrow.
Catchment areas
PROBLEMATISATION Secondary schools
Green areas
Primary schools
Distances
Bus station
Green spaces
Rivers
The popular suburb also increases the extent of impermeable surfacing and many natural rivers have been covered with buildings and roads. Schemes such as Friends of the River Pinn have been introduced to help tackle this loss of natural riverways. These green initiatives are also emerging in schools and among the local community to help improve the quality of the urban environment, such as the horticultural group ‘Harrow in Leaf’.
Predicting weather patterns is becoming increasingly difficult following the rise of environmental concerns. By considering the increasing concerns with climate uncertainty, we decided to explore its potential impact on the Harrow and Wealdstone Opportunity Area. Our initial site visit revealed the area had high levels of concrete surfacing and little green or blue space. Not only did this create a bleak and harsh place, it also increases environmental risks. This becomes an even greater concern when considering the proposed developments for the Harrow and Wealdstone Opportunity Area which will bring a large increase in built infrastructure. Concrete is a highly impermeable building material and encourages water to sit and travel on its surface. Many developments in Harrow have been built over natural rivers and waterways. Obstructing the natural pathway of rainfall therefore needs to be addressed. As with most urban environments, Harrow and Wealdstone have positioned drains and pipes to avoid flooding problems. However, a high number of previous flooding incidences indicate there are issues with this layout and design. We considered these previous flooding events and the river catchment of the Harrow and Wealdstone Opportunity Area to try to predict where future flooding events might occur and how to mitigate them.
Location flooding accidents
SCHEMES & SITES After analysing the data in Harrow we focused our attention to an area just outside the northern borders of the existing Harrow and Wealdstone Opportunity Area. This location has experienced several previous flooding incidences which are largely focused around the River Pinn. The area is situated upstream on higher ground in the water catchment area and on the outskirts of dense urban land. It is located on gradually undulating ground which is predominantly open fields and farmland. Housing settlements and roads around the site tend to interfere with the natural water flow by having narrow and straight drainage systems and poor river maintenance. This means that waterfall from the higher ground is likely to travel faster, become more easily obstructed and cause more severe flooding downstream. In order to address this issue with flooding, we focus our urban design strategy on five main sites. These five sites were chosen to help address the wide scale effects of flooding and the need for site specific solutions. Therefore, each site addresses the problem of flooding in a slightly different way to respond to the surrounding influences. These five sites include; site one called the ‘Rainwater Garden’, site two called Grim’s Ditch, site three is a section of the River Pinn called ‘River Pinn’, site four is ‘the Reservoir’, and site five is called ‘Harrowing for Harrow’. Each site will be signposted at the beginning of the project to draw attention to their location and attract greater awareness of the flooding problem.
SITE ONE - ‘RAINWATER GARDEN’ Our first site is located on a large back garden pond where we introduce planting as a flooding strategy. It is positioned in the north eastern corner of our larger site area and is situated relatively high upstream in the water catchment area. This means we expect it to experience faster water flows. The existing body of water provides a useful precedent for understanding how quickly water flows and remains in this catchment area. It avoids expensive premature earthworks and ensures low disruption to local residents. Furthermore, it helps us to understand how the water, soil and plants might respond to each other following intervention. At this site we will plant trees, shrubs and plants which enjoy wet environments, have relatively large root networks, and are native to the area. This includes willow trees, oak trees, birch trees, gunnera, fern, hawthorn, geranium and fuchsia. Not only does this foliage help retain more water at the site and create more oxygen, it is also attractive to local residents as the native trees and flowers bloom and attract more wildlife. Birds and insects are likely to visit the site more frequently and this will encourage greater pollination at the site. A self-sufficient ecosystem is encouraged which requires low maintenance. Financing is therefore relatively low with initial costs estimated around £5000. Funding sources will include agencies such as the Woodland Trust and the Environmental Agency who have funded similar projects in the area. This interest in planting in London is further encouraged by The Royal Horticultural Society and its National Gardening Week in London.
SITE TWO - ‘GRIM’S DYKE’ Our second site is located on an existing recreational space with medieval decent where we introduce planting and create small levees as a flooding strategy. Benches will also be created on the levees to create a dual functionality for people to sit and enjoy the space. It is positioned in the north western corner of our larger site area and is also relatively high upstream in the water catchment area. The site is predominantly flat with a gently sloping gradient down to the south. Flooding in the area often occurs on Grim’s Dyke and also travels across the ground onto the surrounding roads and housing settlements. This is largely due to the clay based soil which becomes saturated rapidly. At this site we will also plant trees, shrubs and plants which have similar characteristics to those planted in site one, the ‘Rainwater Garden’. However, the trees will be slightly older to enable them to grow more successfully in an area with less existing root networks which help support new growth. The levee will be constructed around the perimeter of the playing field at 0.9m high. This accounts for the maximum anticipated water level at the site of 0.3m and allows additional space for the benches to continue to be used during a flood event. The use of both the planting and the levee system at the site will help slow and retain more water flow. Furthermore, it is also attractive to local residents as the new design will enable resting and play opportunities. Similar birds and insects from the ‘Rainwater Garden’ are likely to also visit this site and pollination is expected to spread. The potential of a wildlife corridor is anticipated to eventually emerge as more mammals become interested and seek sheltered routes to travel between sites. Financing is estimated around £30,000 to include the planting, earthworks and urban furniture. Funding sources will also include agencies such as the Woodland Trust and the Environmental Agency. Local property developers will also be targeted as there is a potential increase in local property values through the improvements made to public space. This includes companies such as Foxtons who currently have proposed new developments in the area.
SITE THREE - ‘RIVER PINN’ Our third site is located on a section of the River Pinn where we introduce planting, dredge the river, and build a permeable pathway alongside the river as part of our flooding strategy. The section we are targeting is in the western corner of our larger site area and covers approximately 3000m from the north to the south of Pinner Park Farm. The site is slightly undulating and flooding typically targets the northern part of the river. This flows over both Pinner Park Farm to the south east and over the housing settlements to the north west. Narrow and straight tunnels have been created in upstream housing settlements which exacerbate this flooding problem by encouraging water to travel faster. Poor river management has led to fallen trees, branches and uneven sediment accumulation which also encourages water to burst the banks. At this site we will also plant trees, shrubs and plants which have similar characteristics to those planted in the previous sites and also encourage more oxygen and increase soil permeability. Dredging of the river will enable water to travel with fewer obstructions and is expected to be required every 1-5 years. Careful monitoring is required to ensure water flow downstream does not increase excessively. Furthermore, permeable pathways will be added alongside the river to create access to the community, such as dog walkers and joggers. This creates a dual function to reduce flood risk and encourage healthier more active lifestyles. It is expected that birds, insects and mammals will also visit the site and water-based animals such as fish and newts. This encourages an aquatic wildlife corridor to emerge alongside more land based wildlife corridors. Financing is estimated around £175,000 to include the planting, earthworks and permeable paving. Funding sources also include local property developers such as Foxtons, alongside Thames Water who have an interest in managing water in London to avoid further costs from issues such as overflow and contamination.
SITE FOUR - ‘THE RESERVOIR’ Our fourth site is located on private farmland owned by Copse Farm where we introduce planting, create a natural reservoir, and build urban furniture along a permeable pathway as part of our flooding strategy. It is positioned in the north of our larger site area and upstream of Pinner Park Farm. The site is slightly undulating and covers a section of the the River Pinn. This upstream section of the river is expected to catch water from the wider catchment area before it travels downstream into the housing settlements. By targeting this site, we can reduce the risk of water bursting onto roads and around houses. At this site we will also plant foliage which has similar characteristics to those planted in the previous sites. A relatively shallow natural reservoir will be dug to contain excess water travelling down the river. This will avoid water traveling rapidly into the housing settlements downstream which have narrow and straight engineered river tunnels which struggle to cope with excess water. Finally, urban furniture and permeable pathways will be added alongside the reservoir to create a new green and blue space for the community to access. This dual functionality inspires new outdoor activities to emerge, such as bird watching, whilst also helping to contain excess water and reduce flood risk. Birds, insects and mammals are expected to visit the site, particularly water-based birds and fish. These are likely to travel along the river towards site 3 and further encourages an aquatic wildlife corridor. Financing is estimated around £375,000 to include the planting, earthworks, urban furniture and permeable paving. Funding sources include Harrow Council, local property developers, Thames Water, the Heritage Lottery Fund and the Wildlife Trust. This is inspired by the near Woodberry Wetlands in London which was awarded funding for a similar scheme.
SITE FIVE - ‘HARROWING FOR HARROW’ Our fifth site is located on council owned farmland called Pinner Park Farm where we introduce planting, create a natural reservoir, build urban furniture along a permeable pathway, and introduce urban agriculture as part of our flooding strategy. It is positioned in the south of our larger site area and is slightly undulating with predominantly grassland used for grazing cattle. This section of our overall larger site area experiences a significant amount of flooding due to its relatively flat profile, proximity to River Pinn and clay soil. The site has experienced significant divide between the area regarding its development, but the largely unanimous decision by the local residents is that they want it to stay as natural and accessible to the public as possible. As discussed in site three, this affects both the farm which is south east of the river, but also the housing which is north west of the river. By targeting this site, we can reduce the risk of water flooding in the areas and harness the potential of water more effectively. We will plant foliage with similar characteristics to the previous sites to ensure continuity and more effective seed dispersal between sites. A natural reservoir will be dug to contain excess water travelling down the river and a small ditch will also run parallel to the reservoir for farming purposes. This will be used as an allotment to grow vegetables and grains which enjoy wet environments, such as quinoa, lettuce, broccoli and butternut squash. These crops will provide the dual function of creating healthy and local food produce, develop agricultural knowledge, and also avoid water flooding the denser urban areas downstream. Finally, urban furniture and permeable pathways will also be added alongside the reservoir to provide access to the allotment sites for the community. This includes existing members of Harrow in Leaf, alongside new actants from schools through the Royal Horticultural Society ‘School Gardening’ programme. An array of wildlife is expected to visit the site and organic pesticides will be used to maintain the success of the crops, but continue to interest local wildlife species. Wildlife is expected to visit the site as it travels from within the site, along the wildlife corridors, and from other new areas around Harrow. Financing is estimated around £375,000 to include the planting, earthworks, urban furniture, permeable paving and agriculture. Funding sources also include Harrow Council, local property developers, Thames Water, the Heritage Lottery Fund and the Wildlife Trust. We also expect smaller scale funding interest from Harrow in Leaf and Capital Gardens with the provision of seeds for the new crops and gardening tools.
SITE ONE - ‘RAINWATER GARDEN’ Initial actants at site one include the local residents, the land owner, pond water, local flora and fauna, and the clay soil. We hope to interest these actants by signposting the location of the site and encouraging more people to acknowledge and visit it. This creates interaction with the site such as treading down grass and it might be visually monitored more frequently. To encourage a new set of dimensions to emerge we promote the National Garden Week in Harrow to raise awareness of its flooding problems and the benefits of planting on floodplains can have. This enroles new actants such as the Royal Horticultural Society who can encourage new seeds and plants to be brought to the site.
Birds
Newts Soil
Flora
Rainwater Pond Fish
People
SITE TWO - ‘GRIM’S DYKE’ Initial actants at site two include the local residents, recreational users, Harrow Council, English Heritage, Historic England, water, local flora and fauna, and the clay soil. We also hope to interest these actants by signposting the location of the site. This promotes interaction with the site such as more frequent visits, more visual site monitoring, and the creation of new paths. To encourage a new set of dimensions to emerge we promote a local precedent scheme to the north at Grim’s Dyke Hotel. This reveals how urban design can preserve and improve medieval sites through careful planting and landscaping. This enroles new actants such as visitors staying at the hotel who might also visit our site and spread awareness of the flooding problem.
Contractor and Engineers
Hotel
Soil
Schools
Heritage Site
Rainwater Grass
Flora Family leisure
Sports players
SITE THREE - ‘RIVER PINN’
Contractor and Engineers
Initial actants at site three include the local residents, Harrow Council, Thames Water, Friends of Pinn, local flora and fauna, water and the clay soil. We will also interest these actants by signposting the location of the site. This promotes interaction with the site such as treading down grass, the creation of new paths, and both visual and physical monitoring of the site through games such as ‘Pooh Sticks’. To encourage a new set of dimensions to emerge we promote a local precedent scheme at the River Brent in London. This educates actants in how river restoration can reduce flood risks, improve health and safety, and also provide opportunities for recreation and education. This enroles new actants such as local Harrow schools who might be interested in replicating the use of the river as a site for education.
Schools Rainwater
Friends of Pinn River Pinn Permeable Paving
Flora
Soil
Commuters
Cyclists
SITE FOUR - ‘THE RESERVOIR’ Initial actants at site four include the local residents, Harrow Council, the Environmental Agency, Thames Water, the Woodland Trust, local flora and fauna, water and the clay soil. We also interest these actants by signposting the location of the site. This promotes interaction with the site such as treading down grass, creating new pathways, and more close monitoring of the site. To encourage a new set of dimensions to emerge we promote a local precedent scheme at Woodberry Wetland’s in London. This educates actants in how reservoirs can reduce flood risks and encourages greater appreciation for green and blue space. This enroles new actants such as contractors and engineers who might be interested in implementing the same scheme at the site to reduce the flooding problem.
River Pinn Contractor and Engineers
Soil Reservoir
Neighbourhoods Flora
Rainwater
Schools
People
SITE FIVE - ‘HARROWING FOR HARROW’ Initial actants at site five include the local residents, farm machinery, Harrow Council, the Environmental Agency, the Royal Horticultural Society, Capital Gardens, local flora and fauna, farm animals, water and the clay soil. We also interest these actants by signposting the location of the site. This promotes interaction with the site such as more frequent visits, treading down grass, creating new pathways, and more close monitoring of the site. To encourage a new set of dimensions to emerge we promote the Royal Horticultural Society ‘School Gardening’ campaign in local Harrow schools. This supports actants in local schools to integrate gardening activities into the curriculum and boost awareness of how it can benefit flooding problems. This enroles new actants such as school children who might become increasingly inspired to garden and help solve the flooding problem in Harrow.
Local Markets
Hotel Community
Allotment Users
Crops Porous Walkways
Allotments
Soil
Reservoir Rainwater Schools
Contractor and Engineers
Co Evolutionary path Developed through the convergence of two main theories, co-evolutionary actor-network theory is a relatively new way of approaching urban design. This addresses the reciprocal aspect of time and progression in co-evolutionary theory and applies the intricate and complex network of actants which are illuminated in actor-network theory. It is useful to consider for sustainable urban design as design often has varying meanings between different actants and evolves during the process. Therefore, to deliver truly sustainable design, it is important to understand these complex relations. We explore co-evolutionary actor-network theory in this urban design strategy through the co-evolutionary pathways of problematisation, interessement, enrolment, mobilisation, and stabilisation. These pathways are both specific to their sites and also interlink with each other, which is seen most effectively in this project during the stabilisation stage. We also outline how our project will be implemented over the course of four phases.
Local intiatives Organisations
Fauna su
(e.g. Royal Horticultural Society, Chuffed)
HTSA
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att ra ct
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Local schools
School initiative
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le c t
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Levees
River
fr o
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Timeline
ro m
Soil
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a nt p la nt
Corridors
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Agriculture
Rersvoirs
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Plants
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e ipat rtic
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Residential initiative
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e ipat rtic
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s difie la mo rricu u
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People
Sign Posts
IoE UCL
(e.g. Friends of Pinn)
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Dog walkers, Runners Children join Harrow Residents Resident close to sites
Allotmetns
grow in
attracted by and use attract and facilitate movement Enrolment Add sign posts around the site area, where future natural corridors are planned
Enrolment Invite local residents around Rainwater Garden and Grim’s Ditch to participate in the National Gardening Week are planned
Enrolment Schools will start having workshops with children and families at Rainwater Garden and Grim’s Ditch about planting for flooding protection
Mobilisation Start building the levees in Grim’s ditch to be able to hold surface water
Mobilisation
Start planting vegetation in Rainwater Garden and Grim’s Ditch in collaboration with London National Park City and SeedBank For Schools
Mobilisation Plants grow and slow down the water runoff at Rainwater Garden and Grim’s Ditch
Stabilisation Create a green corridor between Grim’s Dyke Hotel, Rainwater Garden and Grim’s Ditch. (London Wildlife Trust)
Enrolment Friends of River Pinn (RRC) create an event with the chosen schools about lost rivers
Mobilisation Dredging river Pinn
Mobilisation Start rasing awareness by includingthe Chuffed Crowdfunding Academy about the need for reservoirs
Mobilisation Start building the paths along the riverbanks and start adding vegetation within the floodplain
Enrolment Collaborate with Harrow in Leaf to promote the availability of newallotment sites
Mobilisation Build the reservoir to slow down flash flooding upstream of river Pinn
Mobilisation
Plant vegetation around the reservoir to stimulate the habitat ecologically and help in flooding event
Mobilisation
Build the reservoir to slow down flash flooding upstream of river Pinn
Mobilisation Start connecting the 5 sites by building the blue block corridors
Mobilisation
Rent out allotments and peoplegrow their crops
Stabilisation Generating knowledige about floodingin Harrow, and including local interactionas part of the schools’ curricula
Stabilisation
Help residents maintain the Rainwater Garden through sessions from the RHS
Stabilisation Attracting wildife and their movement between the sites along the natural corridors
Prevention benefits
image source: https://ro.pinterest.com/pin/317081629991329262/
MASTERPLAN
image source: https://ro.pinterest.com/pin/321937073340261356/
Our vision for the Harrow and Wealdstone Opportunity Area is a place for the future generations to enjoy. We address the global problems with climate change and local problems in Harrow with flooding to bring a more sustainable solution to the existing development proposal. Our proposal in the upper water catchment area of the Harrow and Wealdstone Opportunity Area brings benefits to its immediate surroundings by improving access to green and blue space, reducing flood risk, and creating a greater community identity. A ripple effect emerges and the Harrow and Wealdstone Opportunity Area also becomes a place where humans and nature thrive off each other. Planted shrubs and trees spread their seeds to new sites and wildlife corridors emerge where animals seek shelter whilst travelling between the sites. Risk of flooding is reduced as root systems grow into the soil and absorb more water. Furthermore, excess water is captured in our reservoirs and levee systems where we have greater control of waterflow. By working with the natural environment through this sustainable urban design strategy, the new development plan for Harrow becomes more attractive and can be enjoyed by future generations. Not only does our proposal in the upper water catchment area alleviate sustainability problems in the immediate vicinity, it spreads to the Harrow and Wealdstone Opportunity Area to bring economic, environmental and social benefits. This includes the increase in housing prices by improving public facilities, the reduction of flood risk, and the rise in social interaction and physical mobility which has proven to improve individual health and wellbeing. Addressing these three sustainability pillars is arguably essential when designing for present and future generations to come.