Response of saltmarsh recreation by managed realignment to climate and coastal community drivers

Managed realignment is an effective solution in coastal management. This typically involves breaching existing coastal defences, allowing flooding of previously protected land and creation of intertidal habitat, and relocation of the line of actively maintained defences inland. In the UK, creation of intertidal habitat by managed realignment is recommended by strategic plans, yet the uptake of schemes is not keeping pace to meet self-selected targets. The underlying reasons for this slow uptake are complex, span multiple interacting disciplines and are not fully understood. A critical aspect relates to the long-term sustainability and success of the scheme. We explore here how the response of managed realignment to climate drivers leading to intended and unintended consequences intersect with community perceptions.

We focus on a case study in the UK (Hesketh Out Marsh in the Ribble Estuary) where we integrate community co-production with quantitative modelling and long-term environmental datasets. We bring together outcomes from co-creating a shared understanding of the managed realignment system with stakeholders and the local community, with results from downscaled hydrodynamic modelling of the Ribble estuary under present and future sea level, and with LiDAR and Sediment Erosion Table datasets for Hesketh Out Marsh.

Our results show that the managed realignment have both positive and negative influences on the overall social-ecological system. Hydrodynamic modelling results show significant spatial variability in the effect of the managed realignment scheme, which is amplified by sea level rise. In some areas, managed realignment is beneficial but in others it is not. The newly created saltmarsh is slowly accreting, which is beneficial against sea level rise and its long-term viability, but impairs drainage of its terrestrial hinterland. Workshops with local stakeholders revealed entrenched and conflictual perceptions of the process, goals, and effectiveness of the managed realignment scheme. Altogether, this demonstrates the complexity inherent to managed realignment social-ecological systems. Transdisciplinary approaches are critical to better incorporate this complexity into management approaches by enabling to bring together multiple voices and knowledges and to co-create a clearer, more complete shared understanding of the system.