Landscaping To Prevent Flooding

 In Landscaping, Uncategorised

A waterlogged garden is an absolute misery, but with careful landscaping, you can prevent flooding – or at least make sure it doesn’t last for long. Here’s how.

Living on the western side of the UK means that I’ve learned to expect periods of high rainfall. In fact I still remember the chaos in October 2020 when over 120mm of rain fell on Somerset in just 42 hours.  So knowing what the weather is capable of inflicting on a garden, how can landscaping prevent flooding?

Of course, no amount of planning or infrastructure can stop the rain from coming. But what landscaping CAN do is make sure that your garden is fully equipped to cope with heavy rainfall. For that, I take a two pronged approach.

First, make sure that as many surfaces as possible are as absorbent as possible.  And secondly, ensure the garden infrastructure makes it as easy as possible for excess water to escape.  I’m talking getting the levels right and installing a good drainage system. These are all things that you’ll barely notice once a garden has been landscaped…but you’ll certainly notice when they’re not there.

gravel border between patio and retaining wall

Landscaping features such as this gravel border around a patio all help excess water to run freely away from a garden.  They look good too!

Flood Friendly Surfaces

At this point I feel its important to point out, that no matter how well you design and build your garden to prevent it flooding, if the ground around you is saturated and the drainage systems overwhelmed, you might find that your garden is wetter than you’d like.  So if the water has nowhere to go, you’ll find yourself waiting for the waters to subside.  BUT if you can capture some of that rain and release it slowly onto your garden, you’ll reduce the risk of flooding.

One way of doing just that is green roofing.  Have you ever noticed just how much rainwater pours off your garden shed, log store, bin store, summerhouse etc? I’ll wager that even if you have water butts ready to catch it, there’s still quite a lot that escapes into the drainage system.

Green Roofing

A green roof, or a blue-green roof system will vastly reduce the amount of rainwater runoff.  I’ve yet to install one myself so haven’t got any past project photos to share with you but please take a look at the Green Roof Organisation website to find out more about green roofs and how they work.  

Permeable Surfaces

Elsewhere in the garden, it’s been a condition of planning for some time now that front gardens that are used for parking, should have a water permeable surface.  But why stop there? If you know your garden is likely to flood, why not think about having absorbent surfaces in the back garden as well as the front?

Natural lawns are the obvious choice, but how about gravel? Or perhaps you could install patios and paths with the same permeable base layers as you’d use for your driveway?  And don’t forget that your beds and borders are brilliant at soaking up water. So the more planting places you install, the better.

Have you ever heard of rain gardens?  They’re something that you see more and more in commercial developments but there’s no reason why they won’t work in domestic gardens too. In a nutshell, runoff from hard surfaces is directed to a specially constructed sump which is beautifully planted with species that don’t mind if the soil is waterlogged from time to time.  The RHS explains rain gardens beautifully in this article.  

flower garden planted with herbaceous perennials

The beds and borders surrounding this patio and walkway do an excellent job of absorbing excess water

Garden Drainage

There’s more to landscaping than just laying slabs. A good landscaper will take the time to design gardens that direct excess water to an area where it can’t be a nuisance.  Paths and patios will be laid with a slight fall so that water rolls straight off them. 

We do need to be careful where we direct that water though.  Even if the garden naturally slopes towards your house, a good landscaper will adjust the slope of your patio and set the levels so that the rain is directed away from your building.

Next we use drain channels to take the water away to a soakaway, a pond or a designated ditch.  NEVER to your neighbours property, because that can really upset folks.

Gravel borders around the edge of a patio will also help manage excess water.  

The other thing to consider, is retaining walls.  If your garden is terraced, then every retaining wall needs to be engineered so that excess water can escape. If not, then you end up with an awful lot of weight pressing against the wall which in time, may lead to collapse.  Behind each retaining wall will be a drainage system using aggregates, permeable membranes and drainage pipes leading to weep holes.  If you are building your own retaining wall, please please please consult a structural engineer first. It will save you a lot of heartache in the long run.

creating a retaining wall

Retaining walls are carefully engineered with discreet drainage solutions to ensure stability.

Finding A Landscaper Who Understands Drainage

There are people who call themselves landscapers, and then there are actual landscapers.  When you are looking for somebody to help with landscaping to prevent flooding, please make sure that you only get quotes from reputable landscapers who really do understand drainage.  

Landscapers who are members of the Association of Professional Landscapers are carefully vetted before and during their membership to ensure that they always work to high standards.  If an APL member was unsure of any aspect of a garden build, they will always seek specialist advice rather than do a bodge job.  If you are investing money, hope and enthusiasm into your garden makeover, the last thing you want is disappointment.

Visit the APL website here to find a professional landscaper in your area.  

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