The large-scale evacuation of millions of people living across numerous jurisdictions is a crucial concern for government officials in preparation for the possibility of major flooding in Tokyo, officials and experts say.

As advanced planning will be important in coordinating the movement of such large numbers of people, the central and local governments in the Tokyo area launched a commission in June to consider how many people would actually need to evacuate and where they should go in the event a significant flood hits the capital.

The government says 1.76 million residents live in places below sea level, encompassing an area of 116 square km near Tokyo Bay and along the Edo, Ara and other rivers.

In March, a panel of experts under the government’s Central Disaster Management Council estimated in a report that up to 1.78 million people in five Tokyo wards — Sumida, Koto, Adachi, Katsushika and Edogawa, where the combined population totals 2.55 million — may have to evacuate before a major typhoon strikes.

That compares with the approximately 30,000 people who were forced to evacuate due to torrential rains in western Japan this month — an event which left about 200 people dead across 14 prefectures.

“Currently, each ward, city, town and village has its own designated evacuation areas based on local disaster management plans, but we need to figure out which places would have room to accept evacuees from other municipalities,” a Tokyo Metropolitan Government official said.

The commission is tasked over the coming two years with calculating exactly how many people would need to evacuate in case of major flooding or high waves in the metropolitan area. It also aims to identify which evacuation shelters outside the regions that are projected to be inundated will be available to take in evacuees from outside, and assign roles to related entities.

“If the evacuation goes beyond administrative districts, the number of people who must take refuge will inevitably be very big and there are many related issues that also need to be addressed,” he said. “We will have to determine the ability (of areas outside flooded zones) to accept evacuees and how many people they can take, also considering situations such as whether they themselves are located near minor rivers or whether they are likely to be vulnerable to landslides.”

The official also pointed to the need to arrange methods for the mass exodus, including via public transportation, and to consider how to mitigate the concentration of people at train stations and come up with ways to guide evacuees smoothly, especially in dangerous areas such as bridges above overflowing rivers.

Authorities will have to seek cooperation from railway operators to expedite the transfer of people away from hazardous areas as quickly as possible and have police officers dispatched to control traffic to make sure streets do not get congested.

The actions and awareness of individual residents are also important in ensuring their safety in the event of disasters.

The official recommended that people obtain hazard maps of the areas where they live from local government offices so that they can learn beforehand about what potential dangers there are in their respective neighborhoods when catastrophes occur and where the evacuation areas are in their community.

“If they need to evacuate, it is desirable for them to bring with them some food, clothes and water just in case — although they may be provided with them at the evacuation sites — so it’s a good idea to have some stocked regularly,” he said.

“It’s also important for people to have the latest information that would help them decide whether or not to evacuate when a disaster is actually about to happen, so they should do their best to keep informed,” the official said.

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