Devise measures to deal with heavy rains exceeding expectations

Editorial

12:17 JST, August 8, 2022

Record-breaking heavy rains are frequently occurring in various parts of the Japanese archipelago, causing serious damage. The central and local governments need to rethink their flood control measures.

The Tohoku and Hokuriku regions have been hit by torrential rains, causing floods from many rivers, including the Mogami in Yamagata Prefecture. There have also been a series of flooding of homes, power outages and water outages.

It is believed that a stationary front was among the factors that caused cumulonimbus clouds to form one after another, creating linear precipitation bands that dumped heavy rainfall in a short period of time. With more than 500 millimeters of rain in a 24-hour period, parts of Niigata Prefecture were among the areas seeing the most rain since records have been kept.

The rainfall, which exceeded expectations, also caused mudslides, bridge collapses and other damage. Recovery from such damage is expected to take time. The central and local governments should first do their utmost to support the victims.

Linear precipitation bands have caused extensive damage in many areas, as seen in disasters such as the 2020 Kyushu torrential rains when the Kuma River flooded and the western Japan torrential rains in 2018.

Although progress is being made to raise and repair levees, such efforts alone will not be enough to cope with increasingly severe torrential rain disasters. The central government, local governments and businesses should work together to promote regional flood controls, such as creating reservoirs in river basins, to mitigate damage throughout each region.

In a civil lawsuit brought by residents who suffered flood damage in 2015 from the Kinu River in the city of Joso, Ibaraki Prefecture, the plaintiffs sought ¥358 million in damages from the central government, and the Mito District Court ruled last month that the government’s river management was flawed and ordered the payment of ¥39 million in compensation.

In some parts of the river basin, soil and sand had accumulated in forming natural riverbanks on privately owned land, but excavation work by a solar power generation operator lowered the ground, leading to flooding in those parts. The ruling noted that if the government had designated this area as subject to regulations regarding excavations, the damage could have been mitigated.

Natural riverbanks exist throughout the country. It is important for the central and local governments to accurately assess the risks associated with such banks and take safety measures.

A survey last year by the Board of Audit of Japan found that half of the 500 river sluice gates, drainage pumping stations and other such facilities nationwide are inadequately managed. About 40 critical pieces of equipment, including backup engines in case of power outages, are said to have been left out of order for more than a year.

Besides preventing rivers from causing floods, sluice gates and drainage pump stations also prevent smaller waterways from inundating in inhabited areas. Local governments and other organizations are urged to inspect and repair these facilities as soon as possible.

Efforts to have each family member write down on a sheet of paper each person’s own evacuation plan to be taken in the event of heavy rain are also spreading. It is also important for families to discuss in advance how to evacuate when torrential rain is expected.

(From The Yomiuri Shimbun, Aug. 7, 2022)