Mott MacDonald’s team investigated 12 coastal sites on the west coast of the Western Isles including the islands of Benbecula, South Uist, Barra and Vatersay
Following devastating storms in the Outer Hebrides in January 2005 Mott MacDonald has been working on a range of local coastal protection schemes to offer greater protection to the community and shoreline. We were commissioned by Comhairle nan Eilan Siar, the Western Isles Council, to help assess coastal erosion impacts and mitigations measures required to protect vulnerable communities and infrastructure on the coast.

The storm which occurred on 11th and 12th January 2005 caused wide scale damage across Scotland. On the Western Isles the storm was manifested by hurricane force winds, which caused a severe wave climate and a large storm surge. Many parts of the coastline experienced coastal erosion and inundation and ultimately, lives were lost.

The Western Isles are particularly prone to severe storms due to their exposed position on the fringes of the Atlantic Ocean. This position is also becoming increasingly precarious due to the effects of climate change. Many roads were affected by erosion and flooding during the storm, this lead to vital escape and emergency routes becoming severed. As the islands are relatively remote, emergency planning and the provision of escape routes should be key priorities.

The majority of the west coast of the Western Isles is dominated by Machair, an extremely rare habitat in Europe. Machair is characterised by vegetated calcareous sands and is known to occur on the north-west coasts of Scotland and Ireland. Machair supports a wealth of biota and is recognised world-wide for its ecological importance.

Peter Phipps, Head of Geomorphology and Coastal Management for Mott MacDonald explained the importance of the coastal defence issues in this area “The sites investigated pose a unique range of challenges. It is particularly interesting working in the Western Isles because the population density is low but the existing infrastructure is vital to the way of life of the population. We feel that the issues surrounding sea level rise and increasing storminess with climate change are particularly acute in this area owing to its remote location and low-lying nature. The sensitivity of the Machair is also a critical issue as it is one of the rarest habitats in Europe and home to numerous rare species of flowering plants and birds.”

Mott MacDonald’s team investigated 12 coastal sites on the west coast of the Western Isles including the islands of Benbecula, South Uist, Barra and Vatersay. The team found that six of these sites were vulnerable. It was of sufficient significance to the wider community that funding was applied for on behalf of the Comhairle. As a result of the wave impacts from the storm, sites were not only severely damaged, they were also left particularly vulnerable to further erosion and inundation by the sea.

Following the application for funding, five of the six applications to the Scottish Executive were awarded grant aid of £6 million. Mott MacDonald is now looking forward to moving on to detailed design for the five sites. Each site poses unique issues for design in an area with such severe sea conditions, varying needs from the protection of homes or roads to the sensitivity of the natural environment.

Technical direction on developing the project appraisal reports was driven by the coastal team in Foundations and Geotechnics. Project management and environmental assessment was provided by Mott MacDonald’s office in Inverness. This challenging project has highlighted the specialist nature of our coastal management team with further contributions coming from our maritime and environmental experts.

Peter continued, “We are delighted that Comhairle nan Eilean Siar gave us the opportunity to assist on this very important project. It is extremely fulfilling to know that our expertise in coastal management will hopefully be contributing to the longer term sustainability of communities and the environment in the Outer Hebrides.”