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How Garden Wetlands Could Tackle Surface Water Runoff

In the UK, one of the biggest water-related issues facing the country is surface water flooding, something that will become increasingly problematic as time goes on and climate change brings with it an increase in intense periods of heavy rainfall.

Surface water flooding occurs when there’s too much rain too quickly, with both the ground itself and the sewage network becoming overwhelmed by the sheer volumes of water. The problem is then exacerbated when the weather is dry and the ground becomes hard and baked – as we saw earlier in the year, during the heatwave in July.

Estimates from the Department for the Environment, Food and Rural Affairs suggest that there are 3.2 million households in England at risk of this kind of flooding.

Furthermore, it costs more than hundreds of million each year in damages caused by surface water flooding – and it’s expected that this will increase in the future, in line with climate change and a growing population.

Increased urbanisation will put even more pressure on the sewage network, with impermeable surfaces like paving and tarmac unable to absorb water and help reduce runoff.

What’s the problem with surface water runoff?

Surface water runoff is a big source of water pollution. As the water makes its way from the highways and byways, it picks up trace metals and hydrocarbons, as well as other organic pollutants, which then eventually make their way into rivers and other water sources, which can have a devastating impact on local biodiversity and ecology.

Pollution is just part of the problem, however, and surface water runoff can lead to soil erosion, flooding, public health risks through drinking water contamination, dirty water, foul odours, widened stream channels, damaged fish and aquatic life, and reduced recreational opportunities, such as swimming, boating and fishing.

Less water overall will also be seen over time if it is unable to soak into the ground. This means that underground aquifers and other vital resources are not replenished – which could spell disaster later down the line.

The importance of sustainable drainage

Sustainable drainage systems are those that have been designed to manage stormwater and surface water runoff, with the aim being to manage both flood and pollution risks, while enhancing the local environment.

The benefits of such systems include flood risk management, improved water quality, improved biodiversity, more resilient water resources, better communities and better quality of life, more recreational opportunities, education and learning opportunities, and more chances for development.

There are various different solutions that can be employed where sustainable drainage is concerned, but something that has just been put forward as a particularly good option – and something that can be achieved by one and all, it seems – are wetlands.

What are wetlands?

Wetlands are simply areas of land that have been flooded on purpose, either permanently or season by season, to help support the species that live there.

What’s particularly interesting about them is how scalable they are and wetlands can both be found covering millions of square kilometres and small domestic gardens.

This latter idea, in fact, is something that has just been put forward by Tony Juniper, the head of Natural England, as a way to help mitigate the effects of drought and drive down biodiversity loss.

As Mr Juniper asserts, front and back gardens that boast lots of concrete, paving and other impermeable surfaces aren’t able to hold much water, which means they could potentially contribute to sewage spills into the nation’s rivers, lakes and streams thanks to surface water runoff.

According to the Guardian, he’s now suggesting that gardens should perhaps be flooded in order to create these wetlands on a domestic scale to help hold water and prevent runoff, as well as creating habitats for a range of different species.

He was quoted by the news source as saying: “It’s looking at the extent to which you might be able to interrupt water flow before it gets to the sewage and into the rivers. And that’s an interesting way of engaging people who actually don’t see a connection between their house and the river, by going down this route of making gardens wilder to hold more water.”

How to create a garden wetland

The good news for businesses and individuals alike is that it’s relatively easy and cost-effective to make your own wetland, either at home or on a suitable site at a commercial premises.

In fact, you don’t even need to have any diggable ground to speak of… you can make a miniature version by using a tub or container of some kind and positioning it beneath a drainpipe. Even doing this will help make a difference and increase biodiversity in your local area.

Anywhere that water collects can be turned into a wetland, either big or small. Wildlife species typically prefer ponds with a surface area above four square metres, but smaller sites will still prove very attractive and help ease runoff over time.

The best place to position your wetland is perhaps in a corner or near a fence or shed to help protect it from extremes of temperature in winter and summer. Sunlight is a necessity, however, so make sure that your pond isn’t in total shade.

Positioning it near a building can also be useful, as this means you’ll be able to divert the water flowing out of your drainpipe into your wetland area.

Once you’ve selected your preferred site, you can start digging! It doesn’t need to be particularly deep and it can be useful to keep the bottom of the pond within arm’s reach in case something gets dropped in accidentally.

Once the hole has been dug, you can install some liner and start filling your pond. It’s better to either wait for rain to fall from the sky and fill it that way or use water from a water butt rather than tap water, as this can potentially cause harm to wildlife and lead to algal blooms thanks to the nutrient content.

Want to find out more about water efficiency? Get in touch with the H2o Building Services team today.