Mangroves as coastal defense: A model assessment 

With climate change and rising sea levels, coastal hazards, such as erosion and flooding are increasing in intensity and frequency, posing significant threats to coastal areas. Traditional protection strategies including the construction of seawalls, breakwaters, and revetments have been adopted over the years. However, these approaches present challenges such as the high cost of construction and negative environmental impacts. Consequently, there is a drive towards the adoption of Nature-based Solutions (NBS), such as the use of mangroves. With the use of Digital Twin of the Ocean (DTO), the effectiveness of such NBS can be simulated through advanced models. In this study, we explore the What-if Scenarios (WiS) using mangroves as NBS to curb coastal erosion. This research explores WiS by testing mangroves as NBS for mitigating coastal erosion in the Volta Delta region, an area that is particularly lacking in comprehensive observational data. The integration of the DTO framework helps bridge this data gap by providing high-resolution simulations and predictive capabilities. Instead of relying on simplified modeling approaches, this study employs a robust model chain integrated within the DTO to simulate different configurations and densities of mangroves, The work explored three (3) WiS which include: the beach without mangroves, mangroves positioned at the back of the shoreline, and mangroves placed within the intertidal zone. The model validation against measured coastal profiles shows strong agreement with observed erosion trends, providing accurate predictions of sediment volume changes. The results demonstrate a significant reduction in erosion, with mangroves at varying densities offering protection between 18% and 100%. In scenarios with high densities of mangroves introduced in the intertidal zone; the shoreline was fully stabilized. The results of these simulations demonstrate the potential of mangroves as a dynamic coastal defense strategy, with DTO applications providing a valuable tool for testing and optimizing NBS interventions. This study contributes to the ongoing development of mangroves as an NBS for coastal defense strategy demonstrating how DTO applications can effectively test and optimize intervention. By addressing the scarcity of observational data, the DTO framework enhances our understanding and predictive capacity for coastal dynamics. These findings support the broader goals of the UN Ocean Decade by aligning with global efforts to enhance resilience through sustainable, data-driven coastal management strategies and inclusive science-policy-society interfaces.