About this Research Topic
Tropical coral reef-lined coasts are becoming increasingly vulnerable to wave-driven marine flooding due to climate change and the degradation of coral reefs. While progress has been made to increase flood resilience on sandy shorelines, coral reef-lined coasts need special consideration due to their unique characteristics. Firstly, coral reefs are living bio-geomorphic systems whose structure and roughness is highly dependent on their ecosystem health. Reef health is globally under threat due to local stressors, ocean acidification, and global warming, and it is anticipated that the decline of coral reefs will diminish their ability to protect the coast. Secondly, reefs are typically fronted by steep foreshores and backed by steep beaches, which typically give way to flat, low-lying hinterlands. The maximum elevation of atoll islands is often less than 3 m above sea level, which makes these islands highly vulnerable to marine flooding events. Even on high islands, practically all critical infrastructure is located on low-lying coastal plains.
Disaster Risk Reduction (DRR) measures will become increasingly important on coral reef-lined coasts to manage flood risk. Early Warning Systems (EWS) are powerful DRR tools, which allow local authorities to issue warnings, coordinate preparedness and evacuation measures, and reduce risk to life and assets. Short-term forecasts (typically up to 7 days) of extreme high sea level events produced by an EWS are primarily dependent on the atmospheric and ocean dynamics such as storm waves and seasonal and interannual variability in regional and local sea level. Although these extreme events can cause damage to both natural and built infrastructure, frequent marine flooding will also cause salt-water contamination of the fresh water lenses, leaving them unusable for human consumption and/or agriculture. With increasing frequency and severity of such extreme events predicted in the coming decades, particularly along low-latitude coastlines, other forms of adaptation will be required to support island communities. Building resilience into natural, built, and socio-economic environments requires adequate time for planning and implementation. Furthermore, for coasts where adaptation is not feasible, communities will be forced to migrate landward or relocate entirely, likely leading to significant cultural and societal impacts. Long-term projections of future changes are therefore key to coastal adaptation and need to account for changes in coral reef biogeomorphology and anthropogenic interventions, including engineering structures, along with trends in climate, waves, and sea level. Thus, the development of accurate EWS and long-term modeling capabilities are important for the current and future management of flood risk on coral reef-lined coasts.
To advance our understanding and skill at predicting flooding on coral reef-lined coasts, a concerted effort from a number of disciplines, including climatology, oceanography, geology, and ecology, is required. This special issue focuses on advancements in understanding and predicting local sea levels, offshore wave climates, wave transformation and water levels across reefs, and linkages between coral reefs and island dynamics. Summaries of current local or regional-scale studies, including modeling exercises, are encouraged, especially if they evaluate responses to changes in sea level or the impact on infrastructure, habitats, agriculture, freshwater availability, etc.
Keywords: coral reef, coasts, flooding, sea level, waves
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