Nature-Based Solutions to Mitigate Coastal Floods and Associated Socioecological Impacts

Abstract

Despite its importance in supporting the global economy and to accommodate an ever-growing population at the coast, many of the coastal ecosystems such as mangroves, reefs, seagrass meadows, salt marshes and dunes had in the recent years an accentuated decrease in their coverage. The loss of coastal ecosystems, among other problems, leads to the loss of natural capacity for flood mitigation and coastal erosion. Since a considerable share of the coastal population is living in flood-prone areas, the loss of capacity of the ecosystems to mitigate the impacts of floods and coastal erosion can increase the vulnerability to natural hazards such as storm surges, hurricanes and typhoons. This is especially relevant in a context of increasing sea-level rise and intensity and frequency of extreme weather events, both increasing the risk to lose lives and assets. Coastal flood mitigation has been done primarily through the use of hard grey infrastructures. However, these types of structures can have long-term impacts on coastal ecosystems, require continuous maintenance and, in the face of extreme events, may represent an inefficient way to prevent coastal degradation. This called the attention of scientists and decision-makers towards the role of nature to mitigate the impacts of coastal floods through nature-based solutions (NBS). NBS, under the framework of ecosystem-based management, are interventions that aim to reduce the impacts of coastal flooding and erosion and simultaneously enhance ecosystems, biodiversity and natural resources. NBS can use (1) natural solutions (e.g. marine protected areas), (2) soft engineering and ecological restoration (e.g. beach nourishment) and (3) hybrid solutions, which integrate natural and grey infrastructures. Recently, NBS are gaining popularity and are part of coastal management strategies in many countries. Despite their efficiency, it is still a new practice, and therefore concerns are raised regarding their environmental and anthropogenic impacts. Also, there are some drawbacks and pitfalls that need to be overcome to increase NBS implementation. In this chapter we make an overview on the need for NBS for coastal flood mitigation, its implementation in a worldwide context, their impacts on the coastal social ecological economics systems, drawbacks and opportunities to improve their acceptance.