EDITORIAL : Prioritize safety in disaster damage prevention, urban development
TOKYO (The Japan News/ANN) - It is necessary to implement disaster damage reduction measures even at the stage of community development, with a view to preparing for a succession of disaster risks.
The Land, Infrastructure, Transport and Tourism Ministry is set to reinforce restrictions on urban development in areas where great damage could result from disasters caused by sediment movement, among other things.
One feature of the plan concerns areas designated as “red zones” on hazard maps that indicate the extent of danger from disasters. As a general rule, these zones will be excluded from the list of residential sections in compact cities, where housing and commercial facilities are concentrated in the central area. The sections in question are specified as areas where people are encouraged to live.
Another case concerns “yellow zones,” which can expect to be inundated despite a rather low degree of danger. If a zone designated as such is marked on a hazard map, the plan will require local governments to lay down guidelines for preventing damage resulting from a disaster, such as boosting preparedness for evacuation, and building and reinforcing embankments. The ministry has submitted to the current Diet session bills aimed at revising the Special Measures for Urban Renewal Law and other legislation.
Once a disaster erupts, people’s lives are at risk. Given this, the plan’s purpose of restraining urban development in high-risk areas is understandable.
Of 275 local governments that have already devised compact city plans, 13 municipalities still include red zones in the areas in which people are encouraged to live. More than 90% of all local governments have yellow zones in these sections.
Although it is important to pursue convenience in city planning, the safety of residences must be secured first and foremost.
In fact, during Typhoon No. 19 last October, there was a succession of cases in which damage occurred in places designated as inundation hazard areas on hazard maps. The lesson learned from this must be utilized for new community development efforts.
New flooding risks
However, more than a few local governments find it difficult to cope with this task.
Many people live on slopes that are highly susceptible to sediment disasters in places close to mountainous areas, as well as in low-lying areas expected to suffer damage from floods and tsunami.
In accordance with the circumstances of each community, it is important to first of all promote such efforts as setting guidelines for disaster risk reduction, thereby striving to reduce the impact of disasters.
Typhoon No. 19 highlighted new flood-damage risks in urban communities.
There were protracted power failures and water cutoffs at a high-rise condominium in the Musashi-Kosugi area of Kawasaki, as its underground electrical installations had been inundated in the typhoon.
At high-rise condominiums, as much living space as possible is allocated to aboveground floors, making it likely for power distribution and other equipment to be installed underground.
It is worth considering measures to promote disaster damage reduction, such as relaxing regulations on the floor-area ratio for tall condominiums where equipment such as that for power distribution has been installed aboveground.
There was also a lot of flooding inside drainage facilities, when rainwater poured into sewage pipes in excess of their drainage capacity then flowed back out onto the ground and caused flooding. About 60% of building floods caused by Typhoon No. 19 were attributable to drainage inundation.
It is advisable to promote such efforts as the construction of underground facilities to temporarily store water. Some areas have produced hazard maps that include drainage flooding forecasts. The central and local governments should make these efforts fully known to residents.
(From The Yomiuri Shimbun, Feb. 12, 2020)