Scientists to capture flooding information in rain garden



Flooding experts from Heriot-Watt University are helping the Royal Botanic Garden of Edinburgh (RBGE) tackle flooding with the creation of a rain garden.

The new rain garden will be planted on the Birch Lawn, which can often become waterlogged and flooded after heavy rain.

Rain gardens are shallow planted basins that allow rainwater to drain naturally into the ground using free-draining soil. Their planting includes native shrubs, wildflowers and grasses that can withstand occasional flooding while also improving biodiversity.

David Knott, curator of living collections at RBGE said: “The climate is changing, and in Scotland heavy rainfall is becoming more frequent and intense.

“We are creating a rain garden in partnership with Heriot-Watt University to reduce the impact of heavy rain in the garden.

“We will be investigating which native Scottish plants, shrubs and wildflowers are best placed to help the rain garden hold and slowly release rainwater into the soil, as well as cope with drier conditions.

“Not only will the rain garden provide a simple, attractive and wildlife friendly way of reducing flood risk, it will also provide inspiration and knowledge for visitors and other institutions who may need to solve a similar problem.”

Dr David Kelly from Heriot-Watt University, whose research focuses on finding nature-based solutions to rainwater flooding problems, has been studying the Birch Lawn site for months to begin designing the rain garden.

Dr Kelly said: “We will be using the new rain garden at RBGE as a living laboratory so that we can monitor how well it performs during different rainfall events and what impact it has in reducing localised flooding.  

“So that we can tell how well the rain garden works, we are carrying out rainwater surface flow simulations to map where rainwater currently flows following heavy downpours. We are also carrying out soil infiltration tests to check current soil conditions.

“We'll then enhance the infiltration capacity of the soil by adding gravel so that more of the rainwater flowing into the rain garden can be captured and stored by the soil and planting.

“Once the rain garden is in place we will use sensors to monitor rainwater flow volumes and depths, soil moisture levels and more.

“We will also monitor the health of the native planting to check how well they cope within the rain garden. The most critical test will be monitoring its impact on localised flooding in this part of the garden.

“Scotland can expect more episodes of intense rainfall in the years to come, and it is vital that we start to adapt our local landscapes and communities to help improve resilience to this change.”

The rain garden is currently under construction at the RBGE. Once complete, visitors to the RBGE will be able to learn more about the rain garden from interpretation around the site, and information on the RGBE website. Heriot-Watt University and RBGE are working together as part of the Edinburgh Adapts Climate Change Adaptation Action Plan, which aims to help the city adapt to the challenges of a changing climate.