The Yomiuri ShimbunIt is hoped that the latest flood control-related draft report will serve as an opportunity to strengthen precautions against flood disasters.
A working group at the Central Disaster Management Council has compiled a draft report regarding how a wide-area evacuation should be carried out in the event of a large-scale flood disaster.
As a particularly serious case of flood damage, the report presumes a flood disaster in a large city area. It outlines measures to transfer as many as 1 million residents to safe locations in as short a period of time as possible.
Flood disasters have taken human lives almost every year in this country. There are many sea-level zones vulnerable to flood damage in such major urban areas as Tokyo, Nagoya and Osaka. Nagoya and other areas were inundated for a long period of time due to the 1959 Ise Bay Typhoon.
It is indispensable to formulate disaster damage prevention plans that give consideration to wide-area evacuations if huge typhoons and storm surges strike.
If a large number of residents stay in a disaster-stricken area, there will be concerns about a greater possibility of secondary damage resulting. That is why a large-area evacuation is desired in such cases.
Many people think they will be safe if they evacuate “vertically” to such places as upper floors in buildings. However, precedents both at home and overseas show there is a good possibility of buildings being flooded for more than two weeks.
During that time, water supply, sewerage, electricity and gas supply would be halted, and it would be difficult to secure food supplies there. An evacuation could change to a “siege.”
Work with residents
When Hurricane Katrina struck the southern part of the United States in 2005, it took more than one month to drain the water from New Orleans. Sanitary conditions deteriorated and infectious diseases spread there.
To prevent such a situation, the draft report lists residents in flood-prone areas — where all rooms are forecast to be submerged or buildings are expected to be flooded for as long as three to seven days — as people subject to wide-area evacuations.
The council will now go on to formulate relevant guidelines and urge pertinent local governments to consider destinations and methods for evacuation.
Local governments have a heavy responsibility to ensure that residents in their areas understand the importance of wide-area evacuations, and to organize necessary arrangements in cooperation with residents.
The draft report makes tentative calculations, citing five Tokyo wards in coastal areas, including Koto and Edogawa, as model cases. The number of residents subject to evacuations stands at 1.78 million, including voluntary evacuees. It would take them as long as 17 hours to finish evacuations by train, on foot and by car.
The report also states that effective evacuations would be made possible by traffic regulations and through such measures as ensuring that residents first gather at nearby schools and other buildings and then go to train stations, depending on the level of congestion.
The five ward offices have already set rules requiring a wide-area evacuation advisory to be issued 24 hours prior to the arrival of a typhoon and other disasters. However, there has been a lack of significant progress in considering methods for leading people to evacuate and securing places for evacuations.
To facilitate smooth wide-area evacuations, there are tasks to be tackled in many fields. City, ward, town and village governments should promote close cooperation with the police, fire stations, the Self-Defense Forces, railway companies and others. The central and prefectural governments should possess the capabilities to conduct necessary coordination in this respect, too.