The Netherlands (Part 1): Rainproofing
Whilst on a trip visiting a garden I designed in Gouda (around an hour’s drive south of Amsterdam), I took the time to explore both cities to try to understand the Dutch approach to gardens, planting, and public spaces. In this first article on the Netherlands I will look at water - what problems it causes and how plants can provide solutions.
In The Netherlands, water is so closely embedded into everyday life that it has become part of the culture. Much of the country resides at around sea level, and the extensive canal system means that you are never far from a waterway. It appears this closeness to water has become a normal, accepted part of everyday life. An unintentional virtue of the canals is that it provides empty space between buildings, these voids becoming a visual breathing space. This makes for a more relaxing and pleasurable experience, especially as a tourist.
Canal in Gouda
The elevation, and abundance of water makes the likelihood of flooding far greater in this part of the world. Furthermore, the onset of climate change has accelerated this risk dramatically. ‘The sea level on the Dutch coast can now best be described by a trend of 1.8 mm/year until thirty years ago, and an increased average annual rise of 2.9 mm/year during the past thirty years. This acceleration is consistent with what we know about global trends in sea level rise.’ [Deltares Mar, 2023]
Cities are having to look at the problems of increased and extreme rainfall and deciding how to deal with excess water. One tactic in this battle is to ‘rainproof’ the urban environment. Rainproofing describes the ability to capture, store, and drain water, so that even during a storm, all water is retained. This capture and slow release is the key to preventing floods, putting less pressure on drainage systems to remove water from the city.
So what does this have to do with garden design?
Careful garden and planting design can play a key role in the slow down of water run-off, easing the increasing pressures on the sewer system, and helping to reduce the threat of flooding.
The most common design initiatives include green roofs that absorb large amounts of rainfall before it can hit the drainage system; rain gardens that slow down and absorb stormwater often holding it for up to 48 hours before it percolates through to the subsoil or drainage system; and permeable paving which allows water to drain into the subsoil rather than directly to the sewer system.
Spaarndammerhart, Amsterdam
To take a recent example from my visit, the Spaarndammerhart is an apartment complex in the west central district of Amsterdam, built in 2021.
Aerial image of Spaarndammerhart showing the green roof and solar panel array [Photo: Martijn Sandberg]
Its green roof collects and retains rainfall, whilst at the heart of the complex is a garden with paved walkways around its perimeter. The paved areas feel generous though have been minimally proportioned to reduce run-off. The central garden acts as a rainwater buffer, made up of 100mm deep infiltration crates covered with a growing substrate, allowing plants to be planted upon them.
Inner courtyard of Spaarndammerhart
Low-maintenance plants such as rosemary, fennel, salvia are planted here, perhaps able to tolerate periods of drought, in between downpours. A number of trees have also been planted in the garden.
Monarda and salvia planting of the inner courtyard
The plants of course bring other benefits other than slowing down run-off and absorbing water. The increase in biodiversity and the cooling effect of trees have a positive microclimatic effect. Not least, the emotional and relaxing human response to plants has a great effect on the residents.
Small trees, rosemary, fennel, and other planting in Spaarndammerhart
Rain Garden, Gouda
In Gouda I came across some great planting for the public space and this one caught my eye as something a little different. This is a great example of a city rain garden. A rain garden is a garden of shrubs and perennials planted in a depression in the ground so that water runs into it from the surrounding hard landscaped surfaces, roofs, or lawns. The plants in the rain garden help to absorb water but also remove pollutants and nutrients from run-off water. They absorb 30% more water than lawns and remove 90% of chemicals from it, making them very effective against flash floods or stormwater.
Rain Garden in Gouda
Rain gardens are not wet all the time and have to withstand dry periods. This rain garden has a raised drain, allowing excess water to drain away should the bed become too overwhelmed with water.
Raised drain in rain garden
The planting found in rain gardens often must be resilient, enduring periods of high volumes of water followed by prolonged dry spells. The UK Rain Gardens Guide suggests that a ‘very wide range of plants can be planted in rain gardens, however you should avoid using plants that do not withstand occasional flooding - for example species which are usually associated with dry Mediterranean style gardens, like Lavender.’ Other plants to avoid are those that are susceptible to root rot such as azaleas and Juniper. It is also unwise to plant trees as they absorb water too readily, hindering the progress of neighbouring plants.
In our rain garden in Gouda, there are bullrushes planted in the deepest central part of the bed, water mint and a variety of grasses.
Bullrushes and other mixed planting
Water and play
Speelwater is another way in which water is used in design by the Dutch. Children’s playgrounds have been developed around and incorporating water and nature like nothing I have seen in the UK.
I have read about stormwater playgrounds in places like Berlin, where run-off water is diverted into play areas to be dammed, or played in by children, thereby slowing the water’s route to the drainage system. However, I’d never seen the playgrounds created in The Netherlands to encourage children to play close to water and nature.
In the below play area, situated next to a ‘70s housing estate, water is pumped via solar power, running down a rill into a pond. The pond runs off into a nature reserve.
A water playground in Steinse Groen, Gouda fed by a rill
The playground is surrounded by nature. Having been once marshland, then used for agriculture, it is now returning to something like its natural state. But at its centre, water is where the fun is at.
The water playground in Steinse Groen
Rope bridge over water
Another example of a water playground is the ‘el Dorado’ Natuurspeelplaats at Goudse Hout. Here, nature and water play are interlinked by this playground. The play area is situated within the fens of the nature reserve. What better way of getting children out and into nature.
The water playground stepping stones at Goudse Hout
Rope bridge
Further playground elements
SuDS (Sustainable drainage systems), and rain gardens in particular, have become a personal interest to me ever since covering them when studying garden design. It’s a subject that is going to be increasingly important in the future with the problems caused by climate change. Wherever possible I try to design gardens with SuDS in mind, from using permeable paving to employing green roofs. If my trip to The Netherlands has taught me anything, it is that small changes to our gardens can have a great effect on the local environment, and can still be beautiful, relaxing, playful spaces that we all long for.
References
https://www.deltares.nl/en/news/sea-level-rise-on-the-dutch-coast-has-increased
https://www.rainproof.nl/english
https://www.wwno.org/latest-news/2020-03-11/water-ways-the-dutch-are-rainproofing-their-big-cities
https://korthtielens.nl/en/architecture/spaarndammerschoollocatie/
https://groundwater.org/rain-gardens/
https://raingardens.info/wp-content/uploads/2012/07/UKRainGarden-Guide.pdf
