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To protect "Jurassic Beach" of Amami Oshima from erosion and tsunamis

I have visited several islands during my eleven years in Japan, and Amami Oshima is my favorite due to its unspoiled nature, friendly people, and cultural heritage. Japanese people have a somewhat different attitude toward the sea than Mediterranean people. The swim season is very short in Japan, and most beaches are desert for most of the year. This fact has contributed to keeping the naturality of some coastal areas, primarily located in the southern part of the country. Nonetheless, recently, those pieces of paradise have been spoiled to create massive seawalls, "officially" adopted to protect the coast from erosion and tsunamis.

Katoku beach – all images: Matteo Belfiore

The case of Katoku beach – the so-called "Jurassic Beach" of Amami Oshima – shows the risks and challenges of this outdated approach for coastal protection and invites us to find sustainable alternatives to protect the local communities while safeguarding the natural biotopes.

"Saving Japan from Seawalls" is the title of a recent press conference at The Foreign Correspondents' Club of Japan. The discussion - moderated by the Italian journalist Pio D'Emilia – featured an exciting speech of Jean-Marc Takaki, Director of the "Association for the protection of Amami's forest, rivers, and coastal ecosystems."

I met Jean-Marc in 2020 during my first trip to Amami. He kindly brought my wife and me to visit Katoku beach. This magical place immediately became one of the best memories of my life. Entering the beach through the Kami-Michi (God's path), we had the feeling of traveling back in time. Katoku is a paradise out of this time, out of this world. Possibly, it is also one of the few remaining pieces of authentic pristine nature in Japan. Its unique biodiversity includes four hundred shellfish types, black rabbits, Ishikawa frogs. It is also the only beach in Amami where giant leatherbacks lay their eggs.

According to Takaki, the beach features a rare geomorphological process that generates constant changes in the beach profile. Crossing the entire coast, the river's flow helps accumulate sand during the winter to protect the seashore and the village during the typhoon season. Nature protects itself until we block its processes with our arrogance.

For ages, the Japanese have been prone to live and work in harmony with nature. The traditional house, for example, was designed to relate harmonically with its natural context. Even the kanji used for "home" (家庭) stem from the words house (家) and garden (庭). This concept of 'nature architecture' shaped the Japanese landscape for millennia, creating a blurred line between nature and the built environment.

The traditional Japanese gardens were conceived to reproduce nature in its pure essence. Here, the highest level of artificiality generates the strongest impression of naturality. This tension between the will to dominate nature, and the awareness of being overwhelmed, contributed to developing the finest cultural and natural heritages in Japan. Then, the concrete arrived.

Since the 1950s, Japan started promoting sizeable civil engineering projects to fuel the nation's economic development after the war. Something similar also happened in Italy in the same period, until the middle 80s, when landscape constraints started to be imposed. Unfortunately, Japan seems still not aware of the importance of protecting the coastal heritage, lacking proper integrated coastal management.

People often don't even realize this problem. Most hadn't seen the natural beach environments before the concrete structures were installed, blocking the ocean's view and limiting the access to the shoreline.

Giovanni Masucci - Italian marine biologist at the University of the Ryukyus – has studied the impact of Coastal Armoring and its contribution to shrinking the beaches. "If we fix the coastline with hard structures, the beach is not free to shift backward or forward, and this leads, in many cases, to beach disappearance," says Masucci to describe the process of passive erosion.

Especially after the big earthquake and tsunami that affected eastern Japan in March 2011, huge landfills and massive seawalls have buried thousands of kilometers of coastlines. People of the northeast coast have rebuilt their lives alongside massive sea walls. The actual effectiveness of such barriers has long been debated.

Some critics argued that the walls offered little protection against major tsunamis, with failures that can become catastrophic. Many experts have also pointed out that the walls provide residents with a false sense of security, discouraging a quick evacuation.

Seawalls in Amami Oshima

Last but not least, the well-being of coastal communities shall also be taken into consideration.

'It feels like we're in jail', says, for example, one of the locals affected by the giant seawalls. "Everyone here has lived with the sea, through generations. The wall keeps us apart - and that's unbearable." Locals are now feeling like prisoners separated from the sea with a wall that they didn't ask.

Seawalls in Amami Oshima

In ancient times the villages were set close to the sea but primarily for functional reasons, for example, to access the fishing boats quickly. Nowadays, the risks of living on the seaside, in tsunami-prone areas, are far higher than the benefits. Therefore, it is evident the necessity to move homes and infrastructures behind a broad buffer zone. Many coastal villages have already been transferred to higher grounds to avoid tsunami-related risks.

When relocation is not an option, bioengineering can help. Several academic studies have demonstrated its efficiency in reducing erosion, storms, and tsunami damages. For example, scientists concluded that "mangroves can be as effective as concrete seawall structures to reduce tsunami effects".

This sustainable approach has already been adopted with success in Japan. It is the case of the Eco-DRR (Ecosystem-based Disaster Risk Reduction) promoted by the Nature Conservation Bureau, Ministry of the Environment. The main strategies promoted by the document are to avoid exposure through buffer zones and to reduce vulnerability through tailored bioengineering.

According to Stanford researchers, "a careful engineering of low, plant-covered hills along shorelines can mitigate tsunami risks with less disruption of coastal life and lower costs compared to seawalls."

The Japan Times recently documented the 350 kilometers of seawalls built-in Tohoku since 2011, posing an interesting question. Are the walls a premonition, a dystopian future under climate change?

The rise of sea level due to global warming is now indisputable. Coastal protection worldwide will become a crucial issue in the following years and a vast economic opportunity. Governments will have the opportunity to shift those massive investments, currently absorbed by the concrete lobby, toward more sustainable approaches. The Eco-DRR could be a good alternative, but only if accurately tailored to each specific context and biotope.

Raising awareness in the local communities will be the key to achieving sustainable development and cultural sustainability.

Katoku Jurassic Beach is one of those rare jewels on Earth that has it all: Pristine rainforests, pristine rivers and waterfalls, natural delta and river mouth, a wide sandy beach, and an amazing biocultural diversity worthy of World Heritage classification. Preserving Katoku and applying Eco-DRR (Ecosystem-based Disaster Risk Reduction) methods could make Katoku a case model for all of Amami and Japan. As the last concrete-free beach-village in Amami, its potential as a symbol of hope and change is immense and extremely valuable going forward.

www.amamiworldheritage.org