Flooding was identified as the top environmental risk to the UK over the next century by the recent UK Climate Change Risk Assessment (CCRA). Sarah Hutcheon, SNH’s Senior Adviser on Freshwater Policy, explains how we can manage this risk.
In the winter of 2015/16, the UK reported the highest 24-hour and 48-hour rainfall totals ever recorded with severe flooding in the Scottish Borders, Dumfries and Galloway and Aberdeenshire. These floods highlight the need for us to continually improve our understanding of flooding and how to mitigate against it.
Flooding is a natural process, inundating habitats and species, moving sediment and creating new habitats. But climate change is expected to increase the frequency and severity of flooding. In addition, some of the ways we manage land and build developments can exacerbate the impact of flooding. Flooding of people’s homes and businesses causes great distress and damage and we need to manage these risks with all of the tools that we have available to us.
In Scotland, understanding how catchments can help us manage flood risk is built in to our flooding legislation. Natural flood management (NFM) is the term often used for working with nature to manage flood risk. The Scottish Environment Protection Agency (SEPA), local authorities and other bodies are required to work together to develop strategies and plans to manage flood risk. As part of that process they have to consider the contribution that NFM can make to flood risk management. NFM measures aim to slow the flow of water or store it in catchments. Measures include tree planting, river restoration, blocking ditches in peatland and restoring saltmarshes. The range of NFM measures that can be used is described in the Natural Flood Management Handbook that was produced by SEPA last year.
More research is needed to help us understand the contribution that different NFM measures can make towards managing flood risk. But they can certainly help slow and store water during smaller, more frequent floods. They can also contribute towards managing larger flooding events in addition to the more traditional flood walls. As well as managing flooding, NFM measures can also store carbon to mitigate against climate change, improve water quality, improve habitats for biodiversity and create pleasant places for people to live and work in.
In our towns and cities, as well as flooding from rivers or the sea, flooding can also occur due to accumulated surface water. As more and more of our urban areas are paved over or built on, there is less opportunity for rainfall to soak into the ground and this can lead to flooding and also to pollution, as the drainage network becomes overloaded. But we can look to manage surface water run off by using green spaces in urban areas and creating sustainable drainage systems (SUDS). Space can be made to keep water above ground, slow down runoff and allow it to safely soak away, rather than overwhelming the drainage network or flooding buildings. Using these spaces in our urban areas for this purpose is often referred to as green infrastructure.
As part of our work in this area, SNH is supporting a Royal Society of Edinburgh conference on flooding on 15 March. This conference, How can we learn to live with floods – challenges for science and management, covers a wide range of topics including the impact of climate change and how we can plan our cities and manage our catchments to help us manage flood risk. There will be a series of presentations during the day and there is a free panel discussion in the evening. You can find more detail on the programme and how to book a place on the RSE website.