Mangrove forests as a nature-based solution for coastal flood protection:Biophysical and ecological considerations

Nature-based coastal protection is increasingly recognised as a potentially sustainable and cost-effective solution to reduce coastal flood risk.It uses coastal ecosystems such as mangrove forests to create resilient designs for coastal flood protection.However,to use mangroves effectively as a nature-based measure for flood risk reduction,we must understand the biophysical processes that govern risk reduction capacity through mangrove ecosystem size and structure.In this perspective,we evaluate the current state of knowledge on local physical drivers and ecological processes that determine mangrove functioning as part of a nature-based flood defence.We show that the forest properties that comprise coastal flood protection are well-known,but models cannot yet pinpoint how spatial heterogeneity of the forest structure affects the capacity for wave or surge attenuation.Overall,there is relatively good understanding of the ecological processes that drive forest structure and size,but there is a lack of knowledge on how daily bed-level dynamics link to long-term biogeomorphic forest dynamics,and on the role of combined stressors influencing forest retreat.Integrating simulation models of forest structure under changing physical(e.g.due to sea-level change)and ecological drivers with hydrodynamic attenuation models will allow for better projections of long-term natural coastal protection.

Aggregated morphodynamic modelling of tidal inlets and estuaries

Aggregation is used to represent the real world in a model at an appropriate level of abstraction.We used the convection-diffusion equation to examine the implications of aggregation progressing from a three-dimensional(3D)spatial description to a model representing a system as a single box that exchanges sediment with the adjacent environment.We highlight how all models depend on some forms of parametric closure,which need to be chosen to suit the scale of aggregation adopted in the model.All such models are therefore aggregated and make use of some empirical relationships to deal with sub-scale processes.One such appropriately aggregated model,the model for the aggregated scale morphological interaction between tidal basin and adjacent coast(ASMITA),is examined in more detail and used to illustrate the insight that this level of aggregation can bring to a problem by considering how tidal inlets and estuaries are impacted by sea level rise.

Ecological impact of land reclamation on Jiangsu coast(China):A novel ecotope assessment for Tongzhou Bay

China’s continuous and rapid economic growth has led to the reclamation of large sections of the intertidal mud coast in combination with port construction,such as that of the proposed Tongzhou Bay port on the Jiangsu coast.These reclamations threaten the local ecosystem services.An ecotope distribution map was created and a hydrodynamic numerical model of Tongzhou Bay was set up to quantify the impacts of reclamation on the ecosystem.Based on the field data and model results,several abiotic features were classified into 11 ecotopes and visualized in an ecotope map of the Tongzhou Bay ecosystem.Validation with spatial distributions of two threatened shorebird species(bar-tailed godwit and great knot) showed confirmation with the mid-range and low-range littoral zones(inundated from 40% to 100% of a tidal cycle),indicating the importance of the areas with these conditions to these populations.Overlaying the ecotope map with recent and proposed land reclamation schemes revealed a loss of ecotopes,composed of the high-range(42%),mid-range(48%),and low-range(38%) littoral habitats,corresponding to a 44%-45% loss of the most important ecotopes for bar-tailed godwit and great knot(mid-range and low-range littoral zones).These results confirm the applicability of the novel ecotope assessment approach in practice.

Youth Participation at the Third UN World Conference on Disaster Risk Reduction

This article summarizes and analyzes the Children & Youth Forum and youth participation in the process during and leading up to the Third UN World Conference on Disaster Risk Reduction(WCDRR) in2015. An organizing committee consisting of international students and young professionals brought together around200 young professionals and students from around the globe to exchange ideas and knowledge on reducing disaster risk, building resilient communities, and advocating for the inclusion of youth priorities within the Sendai Framework for Disaster Risk Reduction 2015–2030(SFDRR). The knowledge exchange during the Forum was structured around a Toolbox for Resilience that connected to the SFDRR section on Priorities for Action. This article presents the outcomes of these young people’s participation in the disaster risk reduction capacity building eventsand policy-making, as well as the follow-up actions envisioned by the young participants of the Forum. The voices of the younger generation were heard in the SFDRR and young people are ready to expand their actions for the framework’s effective implementation. Young people call on technical experts, donors, NGOs, agencies, governments, and academia to partner with them on this journey to create a more resilient tomorrow together.