Limitations of Natural Flood Management measures for Musselburgh

At the full Council Meeting held on 31 October 2023, elected members were advised that Natural Flood Management on its own will not be capable of protecting Musselburgh against its flood risk from a major flood event.

A report was presented that provided a comprehensive update on the use of Natural Flood Management to reduce flood risk in Musselburgh. The report also provided recommendations on new actions that are considered the best way to advance Natural Flood Management, and also Nature-Based Solutions, over the long-term in the River Esk Catchment which were noted and approved.

It was further noted that the council will continue to work to deliver significant sustainable flood risk management, natural flood management, and nature-based solutions both within the Musselburgh Flood Protection Scheme and across the Esk catchment, however it confirms that Musselburgh cannot achieve its flood protection without new physical defences in the town.

East Lothian Council Leader, Norman Hampshire, said: “While we are disappointed that Natural Flood Management measures on their own are not capable of dealing with future flood risks in Musselburgh, I am pleased an approach has now been mapped out that will allow for the advancement of Natural Flood management in the wider Esk catchment above Musselburgh to supplement the flood protection scheme over the years and decades ahead. We look forward to working with partner organisations, and other interested groups, so that together we can continue to prepare for the future impacts of climate change relating to flooding and also deliver actions that will address the needs of the Biodiversity Crisis.”

The report was presented by Alan Stubbs, the council’s Project Executive for the Musselburgh Flood Protection Scheme and was compiled further to nearly six years of consideration and appraisal by the project team on these matters. The report was also able to draw-in the best available information from the Scottish Government’s Natural Flood Management Research project on the Eddleston Water, above Peebles in the Scottish Borders.

The report highlighted that there is often confusion relating to the terms Natural Flood Management, Nature-Based Solutions and Sustainable Flood Risk Management. It clarified these terms and detailed how they applied to reducing the flood risk in Musselburgh.

The Musselburgh Flood Protection Scheme, as currently envisaged, contains a number of major Sustainable Flood Risk Management measures in the river Esk catchment, and specifically:

• Modification of Rosebury Reservoir to hold large volumes of water during a flood event;
• Modification of Edgelaw Reservoir to hold large volumes of water during a flood event; and
• The provision of a large debris catcher on the river Esk by Whitecraig.

The report confirmed that these measures are expected to reduce the flood waters reaching Musselburgh by in the order of 10%. These measures were part of the Preferred Scheme in January 2020 and currently remain a core part of the Outline Design. They are a key part of the Scheme’s approach to having lower new physical defences in the town of Musselburgh. They will also deliver flood risk reduction benefits along a length of the river South Esk.

Nature-Based Solutions is an overarching term that covers a wide range of natural solutions that may bring benefits relating to, for example: flooding, biodiversity, tree planting, habitat renewal, rewilding, peatland restoration, land-use management, river ecology etc.

The report confirmed that the Scheme would continue to work to deliver maximum Nature-Based Solutions within the Outline Design that is currently being developed. This design will next be presented to a full meeting of East Lothian Council in January 2024.

Natural Flood Management is a more specific term and relates to one type of Natural-Based Solution. Specifically, it must deliver tangible flood risk reduction. Often it will deliver many other natural benefits, but fundamentally it needs to deliver flood risk reduction.

The lesson learned from the Eddleston Water research project was that Natural Flood Management had been demonstrated to reduce peak flow by in the order of 5%. In contrast, the Musselburgh Flood Protection Scheme would require in the order of 50% reduction in the peak flow of the river Esk to protect against the present-day risk of a 1 in 200 year flood event. This is before any further allowance for climate change is added.

The report reaffirmed the position of the Scheme: that Natural Flood Management on its own would not be able to protect Musselburgh without the need for new physical defences in the town along the length of the river Esk.

Cllr Hampshire added: “Councillors clearly understand the important part that Natural Flood Management has to play within any strategy for reducing flood risk, and that the use of this approach is a key part of the current Scottish Government guidance. We also recognise that there is a significant desire from members of the public to see a flood protection scheme developed based on the use of maximum Natural Flood Management and both of these considerations are being taken into account in the development of the final design.”

The report identified: (i) that the science relating to Natural Flood Management does not provide evidence that Natural Flood Management techniques are capable of providing the levels of flood risk reduction that are required in Musselburgh; (ii) highlighted that there remain significant challenges relating to the deliverability of such techniques; (iii) that Natural Flood Management techniques often take many years, perhaps decades, to grow and / or mature; and (iv) reported that in some instances assumed Natural Flood management techniques do not end up delivering the flood risk reduction benefits that it was assumed they would deliver.

New actions recommended by the report that will allow the council, alongside its partner organisations, to advance both Natural Flood Management and also Nature-Based Solutions in the river Esk catchment over the long-term were approved:

• That further investigation of the potential for Natural Flood Management is advanced through the processes of the Local Risk Flood Management Plan (for the Forth Estuary); and
• That East Lothian Council works to establish a new independent body for the river Esk catchment that will be capable of advancing both natural Flood Management and Nature-Based Solutions.

Conor Price, Senior Project Manager, commented: “This report was prepared to update councillors on these matters given the levels of misunderstanding and confusion that exist in Musselburgh relating to the ability of Natural Flood Management to be used to avoid the provision of new physical barriers in Musselburgh.”

“I am hugely excited that East Lothian Council have approved these new actions to advance Natural Flood Management and Nature-Based Solutions. It is my assessment that in order to advance these in the river Esk catchment, and simultaneously to advance the Musselburgh Flood Protection Scheme itself, that we need to be honest about what benefits we can expect to achieve from these natural techniques. It is not reasonable to keep saying we want to protect Musselburgh by using nature if the scientific evidence does not back up this position, and / or after years of looking at this matter suitable sites and specific activities cannot be identified.”