Storm Surge: Lessons Learned from the 2018 Japan Floods
In June and July, parts of western Japan were hit by torrential rains, with some regions experiencing record-breaking totals of more than 1,000 millimeters (39 inches) of precipitation in only a few days. The heavy rains led to widespread floods and mudslides throughout the country as rivers broke through embankments and floodwaters reached more than 16 feet above normal levels in some areas, forcing millions to evacuate. At least 225 people were killed in the disaster, making it Japan’s deadliest flood in 36 years.
Catastrophe modeler AIR Worldwide estimated insured losses from the disaster to be between 284 billion Japanese yen ($2.6 billion) and 423 billion Japanese yen ($4 billion). These numbers only account for residential, commercial, industrial and automobile property losses, however, and do not factor in business interruption, losses to land and infrastructure, construction and erection all-risk, marine hull and marine cargo insurance losses, and demand surge costs—the true toll is likely much higher.
In the wake of the catastrophe, experts have sought to gain a better understanding of what went wrong and determine how such widespread damage can be prevented in the future.
The Need for Greater Awareness
Takashi Ohkuma, head of Niigata City Lagoon Environment Research Institute, has been critical about the lack of preventative measures taken by government authorities to prevent flood damage. Many overlook the fact that Japan is built in a disaster-prone area, he noted. “The residential areas around Hiroshima were created by floods,” he said. “Fifty years ago, this area was farmland, and through time it was developed as a residential area. Yet, the people who developed the areas hit by the disaster lack such awareness—both decision-makers as well as ordinary citizens. And so they approved the area for construction while forgetting the reality that it’s a risky, disaster-prone area.”
He believes it is crucial to increase awareness of this inherent level of risk. “I think it is important for people who live there to understand what caused the disaster in the first place,” Ohkuma explained. “First of all, if there is no major levee breach on the river, this big disaster wouldn’t have happened.” In the past 30 or so years, his institute has warned regional authorities responsible for the rivers to reinforce the dikes. “At that time, the methods and technology to do this were lacking,” he said. “But now we have a lot of reinforcement methods and technology. Despite the availability of such methods, the government didn’t implement the reinforcement for the dikes.”
Yukiko Kada, former president of the Japanese Association of Environmental Sociology and former governor of Shiga prefecture, agreed that more preventative measures should have been taken. “As governor of Shiga prefecture, we made a flood prevention policy,” she said. “From my own experience, I believe that, with proper watershed flood protection policies, areas could have been saved.” She cited the example of the city of Kurashiki, one of the cities hardest hit by the rainfall and flooding. “If you look at the Kurashiki hazard map, which shows the dangerous zones with higher risks for floods, it is remarkable that the areas covered by the map are almost identical to the actual floods,” she said. “The two completely overlap.”
This article oringally appeared in Risk Management on November 1, 2018. Continue reading here.