Urban front gardens and flooding
Front gardens, hard landscaping, water butts and flooding
Do you get depressed by the paved over ‘gardens’ of urban streets? I know I do and its something that has bothered me for a long time. It’s not just their boring appearance and complete lack of biodiversity, but the fact it’s making surface water flooding so much worse and that affects the whole community.
I often walk from Salisbury station to the city centre via Mill Road and this takes me past the water meadows beside the River Avon. On the right are glorious views of the water meadows, gardens and the famous cathedral spire, but on the left is a row of classic Edwardian town houses. Only one has a ‘green’ front garden with lawn while its neighbour has a flower bed and a screen of espalier fruit trees around gravelled area. The rest have given over their front gardens to car parking. There’s so much hard landscaping, which together with a large area of roofs, it’s not surprising that the city suffers from frequent floods. You can see this road for yourself on Google Street View.
Yes, the water meadows are designed to flood and cope with excess water but when Storm Henk hit in January, areas of the city were flooded, despite quite a lot of flood protection work having been carried out in recent years. The volume of surface water pouring off the streets, is so large that the water meadows can’t cope as you can see in this drone footage around the cathedral
Front Gardens on the Front Line
Salisbury is typical of many towns and cities in the UK and further afield. The march of the paved over front garden continues, with the RHS estimating that one in four front gardens is now completely paved over. I joined a fascinating webinar last week, organised by CPRE London. There was an excellent line up of speakers including Wendy Allen, the rain garden guru whose course I have attended, Ari Cooper-Davis who works with Our Rainwater and Paul de Zylva of Quaggy Waterways Action Group.
The organiser, Alice Roberts, Head of Campaigns for CPRE London, said in her introduction:
“For years, homeowners have paved over front gardens – often for car parking – without realising they are harming their local area and the planet. Front garden loss is not a trivial issue, but one that can directly affect our lives. In fact, the explosion of paved areas is a major contributor to the misery of residential flooding, putting around one million properties in England at risk. Paving over even the smallest of front gardens also contributes to hotter cities, air and water pollution, and devastates the numbers of vital pollinators. Overlooked, apparently trivial, yet restoration of front gardens would be a simple but powerful tool to combat climate change. People often ask, ‘What can I do to help the planet?’ One answer is literally on their doorstep.”
You can watch the webinar here It’s well worth an hour of your time. https://www.cprelondon.org.uk/news/front-gardens-on-the-front-line/
The Ealing Front Garden project
I am going to highlight one research project that was mentioned in the webinar, the Ealing Front Garden project. Lots of research has been done on the front gardens of the Borough of Ealing, London’s third largest borough. In 2005, a hard surfacing survey found that the 74,300 front gardens occupied a total area of just over 3,00,000m2 representing 5.5% of the total area of the borough. Around 42% of these gardens were used to park one or more vehicles.
On average, a front garden was found to be 68% hard surface, with the hard surfaces ranging from the most popular concrete (50% of gardens) to bricks, paving, gravel and other loose chipping, quarry tiles and tarmac (5% of gardens).
It’s a pretty depressing story that’s repeated across London. If you add the area of roofs (estimated at 26,500 hectares in London), to the hard landscaped total, you get a very large area of impermeable surfaces from which water will just run off into the road and drains, taking along with it chemicals, weedkillers, microplastics, oil, soil, and other debris.
Why do people hard landscape their front garden?
You can probably guess them! Parking, easy maintenance, looks neat and tidy, while government policies, such as switching to EVs, encourage it. Hard landscaping is particularly popular with landlords because of the easy maintenance and tenants wanting parking.
The trend is upwards as there are more multi-car households, limited public transport and financial incentives coming from lower insurance costs for cars parked off road.
Depaving!
The best thing people can do if they have a hard landscaped front garden is to depave. It doesn’t mean that they can’t park their car, but they can replace some of the impermeable surfaces, such as concrete and tarmac, with permeable surface that allows water to soak into the ground. Examples include gravel, chippings, matrix paving, and some of the new permeable materials. There are some problems with these newer materials, but they are better options than the completely impermeable options.
As you will see from my Salisbury photo above, the front gardens lack a soak away or drain where the paved area meets the pavement, so all the water just runs into the road. Its good practice for contractors to include a soak away in the form of a simple French drain or grille into which water can run and soak into the ground. But where they are present, they need to be maintained so if you have one, don’t let it get covered by leaves or filled with debris.
Innovative front garden design
One of the most innovative front garden designs I have seen was this show garden at RHS Hampton Court in 2007, designed by Fern Adler and Heidi Harvey. Here there is still somewhere to park, a path to the door, plenty of different gravels for permeability and interest, plus a low maintenance planting scheme.
Water butts and slowing the flow
We think of water butts of harvesting water, but they have a vital role in slowing the flow in winter. Most gardens have space to install a water butt or two, however small. If you empty them before a storm, you will have capacity to capture a lot of the water that pours off your roof.
I have been talking about a clever water butt design in my talks for the last few years – it’s the slow drain water butt and its been trialled successfully on the Isle of Wight by Southern Water. The out pipe starts about one third down so the water butt never fills to capacity, the empty space at the top being called attenuation capacity. When it rains, the space fills up and then slowly drains away – and this slowing of the flow of water is enough to have a major effect. Even better, you could leave the tap slightly open so captured water drains away very slowly, leaving you with an empty water butt ahead of a storm.
I have read the maths on this and it is complex, but the bottom line is: if you had a classic 210 litre water butt and you left space to store 100l of water you would delay the delivery of that 100l into the drains or street by around 11 minutes. Now multiply that by the number of water butts in a road or village ….
If everybody installed a water butt and used it to slow the flow, just imagine how much water a row of houses or community could divert away from our streets and drains. I have been encouraging gardeners to do just this. It is such a simple idea and we all need to do this, rural or urban. The benefits are absolutely HUGE.
More to come
I don’t have space this week to delve any deeper into front gardens, but I have a lot of information still to share, around the issues of heat island effect, garden design, street trees, biodiversity and more, so I am going to return to this topic in the coming weeks. It would be wonderful if some of the garden designers who read this post could contribute a few ideas!
Please let me know if there is anything you want me to cover.
And finally its frosty!
We escaped the snow but had a hard frost, so I couldn’t resist a few frosty pix of the garden. I just love these frosty mornings with a low sun and photogenic flowers and leaves.
It’s been a pretty topsy turvy week weather wise. We’ve flipped from a balmy 16oC (61oF) to a chilly -2oC (28oF), the sun finally appeared and then we received 30mm of rain over a couple of days to end two weeks of dry weather.
Happy gardening
Sally
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Talks
I am talking at a number of venues in the coming weeks. Most of these clubs allow non members to attend for a fee.
21 November University of Bristol Botanic Gardens
23 November I am talking at the inaugural LandAlive conference at the Bath and West showground on Sat 23 November. The topic is on creating a climate resilient allotment.
4 December Castle Cary Gardening Club
Looking for a Christmas gift for a keen gardener? Did you know you can gift a subscription to Climate Change Garden
There was a nice piece about a Dutch Initiative / competition to encourage people to remove paving stones called Tile Whipping by Jo Thompson here: https://jothompson.substack.com/p/the-dutch-competition-to-green-gardens. Newcastle University did a study a few years back (after the Tyne Monsoon) about the difference it would make to storm water if more houses installed water butts - a significant difference they found. I now have a 2,000 litre one!
We bought a house where the front garden had been paved for parking as they had two cars. I'd like to change it but how expensive would it be? We have brick pavors and have no idea what is underneath, it might be tons of rubble and sand. We probably will alter it eventually but at the moment we are spending our money inside.
The other thing that occurs to me is having invested in a change any new owners could pave it all over again! Maybe we need legislation around this?