Media reported that although there are other options, seawalls have become an important defense tool for coastal communities to protect themselves from tsunami damage. A new study highlights that well-designed seawalls not only provide safety from tsunami damage, but also better protect key industries such as fisheries and tourism.
Japan is a good example, and the seawall has become an important pillar of the country’s coastline defense. Since the 2011 earthquake and tsunami, Japan has spent more than $12 billion on hundreds of miles of coastal buildings. But not all tsunami-prone countries have the same resources as Japan, and for them, a natural-based solution might lead to a more viable proposition.
Forest-covered coastal areas have long been part of measures to mitigate the extent of tsunami damage in many parts of the world, often combined with some other form of engineering barrier. But according to the international research team behind the new study, the guidelines are more aesthetic than science.
“At the moment, our design is not strategic enough,” said Jenny Suckale, senior author of the study and an assistant professor of geophysics at Stanford University. “
The researchers analyzed how a row of hills absorbed large amounts of energy from tsunami waves using numerical models. Finally, they found that hills of a certain size were as effective in reducing the destructive power of tsunamis like standard seawalls, especially when the shape of the hills matched the shape of the coastline and the direction in which the tsunami might strike.
According to the team’s analysis, it is important to establish a large buffer zone because these hills can cause the flow of water to accelerate and cause damage to the surrounding infrastructure. For this reason, the team points out that an optimal design should include staggered hills, of which the larger hills should be located on the coast and smaller inland.
“Our research shows that design is very important… You shouldn’t design this by aesthetic standards. “
Another interesting finding of the study is that vegetation appears to play a secondary role in the tsunami mitigation effect. Although vegetation plays a vital role in preventing erosion and maintaining the shape of the landscape, the main reason is that the mountain itself absorbs the energy of the upcoming waves.
While this type of tsunami mitigation is likely to be cheaper than building seawalls, the more far-reaching benefits may come from the more access they provide to the coastline.
The study was published in Proceedings of the National Academy of Sciences.