Chelsea Flower Show 2013 with irrigation channels
Concept sketch
Climate change and extreme seasonal temperatures are an increasing concern as the planet reaches a critical tipping point. The Met Office identified in 2022 that in the last decade, the UK has recorded eight new high-temperature records which is a worrying trend.
Our maritime climate and typical British summer with mild temperatures and light drizzle has allowed people to garden to great effect over the years. This has been replaced by hot and dry Spring and Summer weather followed by extreme storms with strong winds and heavy rainfall.
As often cited, we receive the “wrong kind of rain” which means that water supply needs better management to tackle the increasing demand, pollution and lack of new infrastructure. The UK currently has 273 major reservoirs that store about 90 per cent of our stock. However, no new reservoirs have been built since 1991 despite the UK population increasing by 10 million during that time.
Rain gardens are an important part of a larger jigsaw aimed at slowing the transit of water from storm cloud to sewers.
Government legislation (Flood and Water Management Act 2010 ) outlined guidelines that all new projects require Sustainable Drainage Systems (SuDS) to help prevent the of flooding homes and businesses. Construction projects therefore require a more considered approach to the management of rainfall to ensure that the natural stages of the Water Cycle are not impeded and water is either re-absorbed or transported to be stored in a controlled manner.
Climate change projections suggest that water shortages will become more frequent, especially in the South-East of England where demand is rising due to a growing population. This will increase pressure on our existing water supplies and we will need to find ways to be more efficient and creative in capturing and using the rainwater that falls on our urban areas.
As well as contributing to more surface water runoff, increasing urbanisation has also reduced wildlife in urban areas. Where green spaces exist, these are often isolated from each other, which means that wildlife habitats become fragmented, preventing some species from being able to move between them. Eventually, this leads to some species being lost from our green environment, to the detriment of the local ecosystem and the human population.
The Landscape Institute promotes, “Water Sensitive Cities” which outlines an integrated approach to water management. This requires landscape / urban designers, architects and engineers to work together with a common understanding. In practice, this concept can be difficult to deliver due to budget constraints and site conditions but mostly outdated thinking.
However, if a project is designed from the outset with SuDS as a central aim then the benefits are huge. There are numerous examples of this new integrated approach being built in the UK which seek to provide the following benefits:
1. Water Quantity: Controlling the amount of surface water runoff and reducing flood risk to maintain the natural water cycle.
2. Water Quality: Filtering runoff to improve water quality and reduce pollution entering our water systems.
3. Amenity Spaces: Using SuDS as an opportunity to create more green and natural places for people to enjoy; towns and cities incorporating urban wetlands, streams, new planting and lakes.
4. Biodiversity: Creating and connecting habitats for wildlife with green corridors and watercourses.
These aims apply to projects of all sizes, so any changes, even within a small courtyard garden, will create a more diverse wildlife habitat whilst contributing to the wider ecological value of the local area. The new goal of many people is to leave a positive legacy, and applying several simple techniques can be a big step towards ensuring our gardens are contributing towards a better environment.