Managed realignment (MR) involves repositioning coastal or river flood defenses to re-establish tidal flooding and restore intertidal ecosystems in reclaimed areas. The restoration of intertidal ecosystems contributes to flood risk management and achieving nature conservation objectives. However, MR often faces resistance from local communities, potentially undermining its implementation. Previous qualitative studies have discussed the role of socio-psychological constructs in shaping public attitudes toward MR, but quantitative empirical assessments grounded in socio-psychological theory are scarce. In addition, the absence of comparative research across multiple cases limits the potential for generalization, making it difficult to apply findings to other contexts and populations. This study contributes to filling these research gaps by examining socio-psychological constructs that shape public support for MR in three case study areas in the Netherlands. We administered questionnaires among households (N = 324) and used multivariate and regression models to analyze the collected data. Results across the case studies point to three socio-psychological constructs that consistently explain public support for MR, including (i) trust in institutions, (ii) outcome expectancies and (iii) emotions. These constructs are intercorrelated, suggesting that they influence each other when collectively shaping support for MR. Strategies to enhance public support could be more effective when they address these constructs in an integrated manner. Moving forward, it is important to explore how public engagement and communication around MR policies could be tailored to leverage positive emotions better and how the design of MR can be aligned with location-specific priorities.

Increased climate impacts threaten coastal functions globally, highlighting the need for multifunctional coastal climate adaptation. Sand nourishment can adapt sandy coasts to sea level rise, mitigate erosion, increase flood safety, enhance ecological habitats and expand recreational space. Therefore, sand nourishment is increasingly regarded as a promising nature-based strategy for coastal climate adaptation. However, despite this growing recognition, the assessment of how sand nourishment design impacts multifunctional adaptation remains limited. In this perspective article, we argue for three key lessons for researchers to optimise assessing multifunctional coastal climate adaptation by sand nourishment. We conducted stakeholder workshops to scope and inform our perspective, performed semi-structured literature reviews to concretise and validate this for international applications, built a qualitative model to visualise our interdisciplinary overview of how nourishments impact coastal multifunctionality, reflected on this in expert workshops, and identified implications for researchers. In this manner, we assessed the effects of nourishment design on coastal morphology, ecology, socio-economics and ecosystem services in realising the key policy goals of flood safety, nature and recreation. We found that sand nourishment design can result in conflicts between policy goals, generate ambiguous outcomes and lead to system-wide feedback effects. As such, we identified three key lessons: (1) conflicts between policy goals require informing political decision-making on prioritisation between coastal functions, (2) concreteness is needed on otherwise ambiguous functions, and (3) ongoing, multidisciplinary system-wide monitoring is essential. We thus call for a holistic approach to sand nourishment design and encourage researchers from diverse expertise and localities to expand on and adapt our findings to optimise informing sand nourishment design for delivering multifunctional coastal climate adaptation worldwide.

Restoration engineering measures, such as managed realignments or building groins, modify the environmental characteristics of coastal intertidal ecosystems. Creating physical modifications that are beneficial to an intertidal system's ecology necessitates an in-depth understanding of the relationships between the abiotic and biotic components of a given intertidal habitat. In this study, we evaluate how hydrodynamics and sediment characteristics drive the development of the benthic macrofauna community during the first 5 years following engineering measures to enhance benthic macrofauna diversity at three locations. The creation of low-energy habitats through groins (Knuitershoek and Baalhoek) and a managed realignment dike breach (Perkpolder) led to the accumulation of fine sediments in all three impact sites. Biomass of benthic macrofauna quickly increased between 2016 and 2020, with successional processes being more important in Perkpolder, where the habitat was started completely from scratch due to a managed realignment, than at Knuitershoek or Baalhoek, where habitat conditions were improved by adding groins. In addition, the density of benthos-eating birds, especially oystercatchers, increased at some of the modified sites. While a low-energy habitat may harbor more diverse assemblages of benthic macrofauna than a highly dynamic one, the extremely high silt content, which is typical for low-energy habitats, may slow benthic community development. The observed increase of biomass at our impact sites highlights the value of the interventions, while the delays in the response of the benthic macrofauna community emphasizes the need for extensive monitoring both in time and space and the identification of underlying abiotic–biotic mechanisms.