Mangrove forests are vital for flood reduction, yet their failure mechanisms during storms are poorly known, hampering their integration into engineered coastal protection. In this paper, we aimed to unravel the relationship between the resistance of mangrove trees to overturning and root distribution and the properties of the soil, while avoiding damage to natural mangrove forests. We therefore (i) tested the stability of 3D-printed tree mimics that imitate typical shallow mangrove root systems, mimicking both damaged and intact root systems, in sediments representing the soil properties of contrasting mangrove sites, and subsequently (ii) tested if the existing stability models for terrestrial trees are applicable for mangrove tree species, which have unique shallow root systems to survive waterlogged soils. Root systems of different complexities were modeled after Avicennia alba, Avicennia germinans, and Rhizophora stylosa, and printed at a 1:100 scale using material densities matching those of natural tree roots, to ensure the geometric scaling of overturning moments. The mimic stability increased with the soil shear strength and root plate surface area. The optimal root configuration for mimic stability depended on the sediment properties: spreading root systems performed better in softer sediments, while concentrating root biomass near the trunk improved stability in stronger sediments. An adapted terrestrial tree resistance model reproduced our measurements well, suggesting that such models could be adapted to predict the stability of shallow-rooted mangroves living in waterlogged soils. Field tree-pulling experiments are needed to further confirm our conclusions with real-world data, examine complicating factors like root intertwining, and consider mangrove tree properties like aerial roots. Overall, this work establishes a foundation for incorporating mangrove storm damage into hybrid coastal protection systems.

ΔENIGMA is a national research infrastructure with various work packages (WP) studying the water and sediment dynamics for nature-based, flexible, and adaptive flood risk management in the Dutch Delta's river-estuary-coast continuum. WP6 joins efforts between TUDelft, Wageningen, Twente, and Deltares Labs to study and facilitate interactions bridging related knowledgecommunication- action gaps. The WP6 designs various tools, such as serious games, using digital and physical interfaces to facilitate collaborations between societal and academic actors while joining efforts within, across, and beyond WPs. Collaborative interactions are considered productive when achieving individual, group, and societal learning about the problem and proposed solutions, the norms and values behind, and the necessary (collective) action f (Barth et al., 2023). This paper presents the TU Delft Game Lab+’s prototype, developed with ΔENIGMA WP2 and TU Delft Serious Game Design students (Kontaxopoulou et al., 2024).