Rain Gardens London
Rain Gardens Sussex
Why have a rain garden?
The UK is considered a temperate climate, but we have occasional heat waves and downpours (2012 was one of the wettest years on record), and both can cause problems.
Existing drainage systems are designed to remove water runoff as quickly as possible, however this deprives the natural water table of the ‘top up’ it needs for drier months. Also, drainage systems often can’t cope with heavy rainfall and this can cause localised flooding.
Rain gardens capture rainfall from any building or sealed surface, such as a road or driveway. The collected water is stored and released into the landscape, draining away into the soil and natural water table. This helps prevent flooding and means water is available in dry periods. It also causes less pollution as when rain water flows across the surface of a road or pathway it is contaminated with salt, heavy metals, oil, antifreeze and other substances. This can end up in streams and rivers where it can damage the aquatic organisms. Rain gardens help prevent this as the plant roots absorb and break down these contaminants.
As well as being functional, a well designed and planted rain garden will be aesthetically beautiful, providing both visual and sensory pleasure. It will attract local wildlife and encourage biodiversity, of birds, butterflies, insects and more. As long as the correct plants are used, rain gardens are easier – and cheaper – to maintain than conventional gardens. In all respects rain gardens are truly sustainable and as we become more aware of the need to create sustainable environments, rain gardens are likely to increase in popularity.
No area is too big or too small to be a rain garden. From private gardens, to super market car parks and industrial estates, rain gardens have the potential to make a real – and pleasing – contribution to the environment. If you already collect rainwater into a butt then you have made a great start. Think about extending this to create subsequent water capture stages and your very own rain garden.
Green Roofs – Putting a layer of soil and appropriate plants on a roof can reduce annual rain water run off by 60 –80%. They look attractive too!
Disconnecting down pipes – Water is diverted into water butts or cisterns, then allowed to overflow into rills, filter strips, or planted depressions and linked to other stages of the water chain.
Storm water planters – These above ground planters sited directly against buildings catch rainwater from the roof. Any excess water not taken up by the soil or plants is collected by overflow pipes that either link into conventional storm drains, or the next stage of the designed water chain.
Landscape swales – These are excavated depressions or channels that are heavily planted and can temporarily store and remove run off water. They are suitable for areas where there is likely to be higher levels of water.
Swales using a mixture of meadow like native grasses and flowering plants have shown a reduction of water flow of up to 41%, compared to a 27% reduction in swales that were just mown grass.
Retention ponds are impermeable basins that will permanently retain water. They are usually the final stage of the storm water chain.
Rain garden plants are selected to cope with extreme weather for short periods of time. They are mainly flowering perennial and grasses together with scattered shrubs, heavily planted to maximise moisture retention.
The result should be a landscape that maximises water infiltration back into the water table, promotes wildlife and biodiversity and has a strong visual aesthetic. This becomes an integral part of an outdoor space, planned with the end users needs in mind.
We would love to share our enthusiasm, so please contact us for more information.
These images do not represent work by Elemental Designs. For more information please visit www.nigeldunnett.info