Experts divided over anti-tsunami sea walls being built along Japanese coast
Construction continues on 400km-long concrete barrier designed to protect against tsunamis
Four years after a towering tsunami ravaged much of Japan's northeastern coast, efforts to fend off future disasters are focusing on a nearly 400km chain of cement sea walls, nearly five storeys high in some places.
Opponents of the 820 billion yen (HK$53 billion) plan argue that the massive concrete barriers will damage marine ecology and scenery, hinder vital fisheries and actually do little to protect residents who are mostly supposed to relocate to higher ground. Those in favour say the sea walls are a necessary evil, and one that will provide some jobs, at least for a time.
In the northern fishing port of Osabe, Kazutoshi Musashi chafes at the 12.5-metre-high concrete barrier blocking his view of the sea.
"The reality is that it looks like the wall of a jail," said Musashi, 46, who lived on the seaside before the tsunami struck Osabe and has moved inland since.
Pouring concrete for public works is a staple strategy for the ruling Liberal Democratic Party and its backers in big business and construction. Local officials tend to go along with such plans.
The paradox of such projects, experts say, is that while they may reduce some damage, they can foster complacency. That can be a grave risk along coastlines vulnerable to tsunamis, storm surges and other natural disasters.
"There's a bit of an over belief in technology as a solution, even though everything we have learned demonstrates that people's own insights and instincts are really what makes a difference, and technology in fact makes us a bit more vulnerable," said Margareta Wahlstrom, head of the UN's Office for Disaster Risk Reduction.
Tsuneaki Iguchi was mayor of Iwanuma, a town just south of the region's biggest city, Sendai, when the tsunami triggered by a magnitude 9 earthquake just off the coast inundated half of its area.
"We don't need the sea wall to be higher. What we do need is for everyone to evacuate," Iguchi said.
A 7.2-metre-high sea wall built years earlier to help stave off erosion of Iwanuma's beaches slowed the wall of water, as did stands of tall, thin pine trees planted along the coast.
But the tsunami still swept up to 5km inland. Passengers and staff watched from the upper floors and roof of the airport as the waves carried off cars, buildings and aircraft, smashing most homes in densely populated suburbs not far from the beach.
The city repaired the broken sea walls but doesn't plan to make them any taller. Instead, Iguchi was one of the first local officials to back a plan championed by former Prime Minister Morihiro Hosokawa to plant mixed forests along the coasts on tall mounds of soil or rubble, to help create a living 'green wall' that would persist long after the concrete of the bigger, man-made structures has crumbled.
While the 'Great Forest Wall' being planted in some areas would not stave off flooding, it would slow tsunamis and weaken the force of their waves. As waters recede, the vegetation would help prevent buildings and other debris from flowing back out to sea.
Such projects would also allow rain water to flow back into the sea, a vital element of marine ecology. Despite pockets of opposition, getting people to agree to forego the sea walls and opt instead for Hosokawa's 'Great Forest Wall' plan is a tough sell, says Tomoaki Takahashi, whose job is to win support for the forest project in local communities.
"Actually, many people are in favour of the sea walls, because they will create jobs," said Takahashi. "But even people who really don't like the idea also feel as if they would be shunned if they don't go along with those who support the plan," he said.
