Increasing population density in coastal regions raises the risk of catastrophic tsunami damage. Traditional protection measures like seawalls are effective but costly and may create a false sense of security. However, strategically placed buffer blocks along the coastlines can be a better alternative since such blocks reflect the incoming flow and induce turbulence, thus dissipating energy and reducing flood damage. This study, using DualSPHysics simulations, analyzed the optimal size and positioning of buffer blocks for maximum possible dissipation of flow during extreme events along the coast. Results show that two or three rows of blocks significantly reduce flow depth and momentum flux, to an extent of up to 30%. These findings enhance coastal protection strategies and improve safety.
Coastal regions are vital due to the dense populations and economic activities they support, with around 40% of the world's population living within 100 km of coastlines (WMO, 2022). This concentration translates to approximately 3.2 billion people, making these areas some of the most densely populated globally. In 2000, low-elevation coastal zones had a population density over five times the global average, and projections indicate this population could exceed one billion by 2050 (IPCC, 2019). Rapid population growth in these areas leads to infrastructure expansion, land use changes, and increased exposure to coastal hazards, such as tsunamis and storm surges, which can cause catastrophic damage (UNEP, 2006; Neumann et al., 2015).
To address the increasing risk of tsunamis, traditional mitigation strategies have been employed, including sea walls and early warning systems. However, these methods have limitations, such as high costs, ecological impacts, and potential sudden failure during extreme events. For instance, early warning systems can fail to provide timely alerts, as seen in the 2018 Palu-Donggala tsunami (UNDRR and UNESCO-IOC, 2019; Oetjen et al., 2022).
Recent research highlights the need for innovative, eco-friendly and more effective tsunami mitigation techniques. One promising approach is the use of buffer blocks, which not only act as wave energy dissipators but also can serve as seats for beach lovers. This concept is inspired by natural barriers like vegetation belts but offers advantages such as less maintenance and space requirements (Kathiresan and Rajendran, 2005; Tanaka, 2007; Baird and Kerr, 2008).