Monday, September 4th, 2017
Weather patterns are shifting and our city’s infrastructure is struggling to cope. Are rain gardens the answer?
Life in 21st century London is different in countless ways to that experienced by previous generations. Technology has made what was science fiction in the 1960s part of everyday life today, the skyline has evolved into a dramatic combination of futuristic glass and historic buildings that have stood unchanged for years, and as for the climate – however much some might try to deny it, there is empirical evidence that flash flooding is on the increase due to rain falling in shorter, heavier bursts than it used to.
Yet one of the few things that has changed very little over the past century is the capital’s drainage network. As urban drainage specialists, we know that London’s sewerage and drainage systems are already stretched to capacity, and as the population grows larger and the floods grow heavier, it seems inevitable that more damaging floods will result.
It is easy to assume that the answer is to create bigger and better drains with larger capacities, but this is easier said than done. The underground labyrinths that have been in place for so long underpin the entire city, and cannot be simply swept away and replaced with a modern alternative – to attempt to do so would take decades, cause widespread disruption and cost an astronomical sum of money.
However, there could be a far more attractive solution, in every sense of the word. Rhiannon Williams is a landscape architect who studied under UK climate change guru Professor Nigel Dunnett, and her Urban Rain Garden, which featured at the recent RHS Hampton Court Palace Flower Show, provided a tantalising glimpse of how effective garden design can incorporate sustainable rainfall management, providing a 21st century solution to a 21st century problem.
The garden is designed with a focus on capturing and utilising rainfall to the maximum effect via a system of planters.
One of the biggest problems with a traditional garden is that when the rain falls heavily, the ground cannot absorb it all, leading to large amounts of run off and the subsequent risk of flooding. The idea of the planters is to slow the progress of rainfall in its journey to the ground, thereby giving the soil more chance to absorb it.
The process begins with the downpipe from a domestic guttering system. This leads directly into the first planter, and when that is full it drains off into the next one and so on, down a terraced slope. Each planter is effectively an independent raised bed – the first is naturally the wettest and is home to aquatic and pond plants, while subsequent planters can be home to a choice of plants, flowers or even vegetables.
Like so many great ideas, the theory is so simple that when seen in action, it leads you to wonder why nobody thought of it years ago. And even better, it gives the opportunity to bring some much needed natural beauty to the UK’s concrete jungles.