Surface Water Flooding in the Garden

There have been a few roof leaks appearing over the last few weeks.

I’ve known about the one in the tunnel for a while, these were caused by pesky birds standing outside on top of the plastic and pecking at the insects inside with their sharp, pointy beaks. 

The shed roof probably needs recovering. The flat roof in the kitchen and water stains on the living room ceiling will need to be addressed at some point too. These can’t really be fixed in a rush in between rain showers, so we’ll have to put up with the plopping noise water drops make in the buckets as the roof drips. 

Thankfully, most of my garden has survived waterlogging or flooding. Others aren't so lucky.

The worst-case scenarios are gardens that get washed away by flash floods when rivers burst their banks.

The majority of flooding and waterlogging in our gardens is less damaging and dramatic and comes from something called “surface water flooding”.

Surface Water Flooding

Surface water flooding happens when water is unable to drain away from the surfaces it has fallen, or sitting in.

It can appear as large puddles, water sitting on paved surfaces outside the house, flowing water and sometimes hidden just under the surface of the lawn.

In cold, winter soils, roots and soil microorganisms need less oxygen, so waterlogging is much less damaging than during warm seasons. This isn’t to say that the plants aren’t affected, it might just take a while longer for the leaves to turn yellow.

Heavy, consistent rainfall is the main culprit although melting ice and snow can contribute.

Normally, if rain falls onto a hard surface, like roof tiles or concrete, it will roll away and find the nearest drain. If it falls onto grassy surfaces, planted areas or bare earth it will be absorbed until the land is saturated. Surface water flooding happens when water that has fallen onto a hard surface cannot roll away or find a drain. It also happens when water falls onto a vegetated or soft surface that is already saturated so it can’t soak up any more water.

When surface water flooding occurs, it can damage plants and also create hazards on paved areas and encourage slippery moss to grow. If it’s particularly persistent the water can cause structural problems for paved surfaces, fences, sheds and outdoor buildings.

There are a few preventative things we can do to help the water along it’s slow meander to the sea.

Clearing Gutters and Outside Drains

Gutters play a key role in channelling excess water away from your home. Regularly check that they’re in good repair and replace any parts that have deteriorated or broken.

Repair Roofs

Keeping an eye on your roof is an important part of protecting your home from heavy rain and snowfall. Rainwater will rely on a smooth, sloped surface to find its way into the gutters and downpipes. Tiled roofs can be checked for loose tiles at least once a year as well as after extreme weather. Pay close attention to any flat or felted roofs as they don’t fare well in Ireland. They are more at home in drier climates.

Water Butts

 It’s a great idea to make good use of it by installing water butts at the base of your downpipes. They’re ideal for capturing water for outdoor use but can only collect a small amount in the grand scale of things.

Driveways

Driveways and parking spaces can be one of the trickiest spaces when it comes to surface water. Whilst it makes an ideal surface for your car, paving these areas with concrete, asphalt or block paving can make it hard for water to soak away.   

Planning

Choose surfaces that allow water to permeate through or run easily off them when garden planning. In addition, take into account that the surface will need a slight fall, or slope, to allow water to drain away from your house and any outdoor buildings.

Drains

It’s not just gutters that need to be kept clear to keep water flowing. Have a look at uncovered drains in the spring and autumn and after big storms.

French drain

If all else fails and you find that you have a more serious water logging drainage problem in the garden, you could have a ‘French drain’ installed. This system is essentially an extra underground drainpipe.

A healthy lawn does a great job of allowing rainwater to flow through the water table.  Plants and trees also play an important role throughout your garden as they will absorb groundwater through their roots.