A case history of co-design and co-deployment of a nature-based solution (NbS) against erosion and slope instability

Abstract

Nature-based solutions (NbS) are increasingly seen as the most sustainable option for addressing climate change challenges such as erosion and landslides. Live slope grid is a NbS used for protection and mitigation of shallow landslides and erosion; it involves a timber grid construction which covers the slope at risk of landslide/erosion with live vegetation planted within the cells of the grid which stabilises the uppermost soil horizons. Live cribwall is another NbS used for retention of unstable soil mass. Vegetation is planted and grows in between the cribwall layers and it anchors the wall to the soil behind while, at the same time, strengthening the backfill. The aim of this case history is to detail the co-design and co-deployment of a live slope grid installed above a live cribwall on a coastal slope in Scotland. The design and construction process is detailed over the range of project stages and will outline stakeholder engagement during this process. Because the NbS structures failed during this process and repair work had to be carried out, this study focuses on sharing the ‘lessons learned’ from the design and construction processes over a timeline of several years. The climate change effects leading to failure of the structure as well as the reactions of the stakeholders are highlighted in this case study in order to help practitioners and other stakeholders in managing similar projects within the framework of sustainability and resilience, especially when the funding is limited. The main conclusions from this study are justification of the urgent need for standardising the design and construction of NbS for slope protection as well as the importance of upskilling and training of the relevant stakeholders in order to incorporate the peculiarities of designing and constructing with vegetation.