Demonstrating the value of beaches for adaptation to future coastal flood risk

This paper presents a method for quantifying the benefits of beaches in reducing storm and long-term coastal flood risk. This method can contribute to cost-effective decision-making on climate change adaptation in many of the world's coasts. Cost-effective coastal flood adaptation requires a realistic valuation of losses, costs and benefits considering the uncertainty of future flood projections and limited resources for adaptation. Here we present an approach to quantify the flood protection benefits of beaches accounting for the dynamic interaction of storm erosion, long-term shoreline evolution and flooding. We apply the method in Narrabeen-Collaroy (Australia) considering uncertainty in different shared socioeconomic pathways, sea-level rise projections, and beach conditions. By 2100, results show that failing to consider erosion can underestimate flood damage by a factor of 2 and maintaining present-day beach width can avoid 785 million AUD worth assets from flood damage. By 2050, the flood protection and recreational benefits of holding the current mean shoreline could be more than 150 times the cost of nourishment. Our results give insight on the benefits of beaches for adaptation and can help accelerate financial instruments for restoration.

Automated summary

This paper presents a method for quantifying the benefits of beaches in reducing storm and long-term coastal flood risk. The method is important for cost-effective decision-making on climate change adaptation in coastal areas. It considers the dynamic interaction of storm erosion, long-term shoreline evolution, and flooding to quantify the flood protection benefits of beaches. The results show that considering erosion is crucial for accurate flood damage estimation and that maintaining present-day beach width can significantly reduce flood damage.