Inundation damage Rural Chofu and Futakotamagawa… October 15th at 22:00 on the Tama River

The Tama River flowing through Tokyo and Kanagawa flooded under the influence of Typhoon No. 19, and the residential area of ​​Denenchofu, Ota-ku, Tokyo and the area around Futakotamagawa Station in Setagaya-ku were also inundated. How did the flooding occur and what damage did it cause?

Flooding around 10:00 on the 12th

According to the Keihin River Office of the Ministry of Land, Infrastructure, Transport and Tourism, the water level began to rise sharply after 6 am on the 12th at the station data about 100 meters downstream from Futako Bridge in Tamagawa, Setagaya-ku.

Heavy rain of over 30 mm per hour continues and the water level rises by about 50 cm.

Usually, the water level of about 2 meters exceeded 6 meters at 2 pm and exceeded 8 meters at 6 pm and continued to rise, reaching 8 meters and 67 centimeters at 9 pm.

The flooding occurred around 10:00 pm, and the Ministry of Land, Infrastructure, Transport and Tourism and the Japan Meteorological Agency announced “flooding information”, which is the highest level among the five warning levels at 10:20 pm, to ensure safety. Called for vigilance.

Rural Chofu Residential Area Water up to the waist ...

Tokyo Metropolitan Police Department's riot police in a residential area in Denenchofu, Ota-ku, Tokyo, in a photo taken after 1 am on the 13th, the members of the Tokyo Metropolitan Police Department ’s riot police in a blue and yellow wetsuit You can see that you are heading to the place where you requested the rescue.

The height of the water reached the waist.

And in the photo taken 30 minutes later, you can see the residents coming back on the boat, illuminating the direction of travel with the lights.

It flows from the undeveloped part

It has been understood how the water flowed in near the Futakotamagawa Station in Setagaya Ward, the Tama River.

According to the Keihin River Office of the Ministry of Land, Infrastructure, Transport and Tourism, the southwest side of Tokyu Denentoshi Line / Futakotamagawa Station has a portion of the levee that has not been maintained for more than 500 meters. I found that water was flowing in.

The river office was taking measures such as putting sandbags in front of the approach of the typhoon, but the water seems to have flowed in over the sandbags.

The undeveloped section is along the river in the lower part of the Tama River in Setagaya-ku, Tokyo, southwest of Futakotamagawa Station on Tokyu Corporation.

According to Takeyoshi Chibana, an associate professor at the University of Tokyo who specializes in river engineering and served as a member of the Tama River River Improvement Project Expert Committee, there was a plan to develop a dike along the river during the Taisho period. The restaurant at the eaves objected that they could not enjoy the scenery when there was a dike, so the dike was constructed along a road about 100 meters away from the river.

Later, houses and condominiums were built between the dike along the road and the river. About 10 years ago, the embankment on the downstream side of the station was built, but there was a debate about about 500 meters upstream of the station.

Associate professor Chibana said, “While there is an opinion that the river is protected with hardware, there is a variety of opinions, such as“ I want to see the river ”, and there is a lot of opinion. It is necessary to think about how to evacuate, how to live along the river and how to develop the town. "

In response to this flooding, the Keihin River Office says that “I want to listen to the opinions of the residents and proceed as soon as possible”.

Inundation damage in Tokyo 23 wards is almost the same as the hazard map assumption

When we interviewed about flood damage to buildings in Tokyo's 23 wards, it was found that as of noon on the 15th, there were 637 cases of flood damage on floors and under floors of houses, mainly in Ota Ward and Setagaya Ward along the Tama River. It was.

Specifically, in Ota Ward, 583 cases centered on Dencho Chofu 4-chome and 5-chome, and in Setagaya Ward, 44 cases were observed in Tamazumi and Tamagawa districts, 8 in Itabashi Ward, and 2 in Toshima Ward. It is that it was done.

The inundation damage is almost consistent with the hazard map assumptions released by the local government, and each district will verify how the damage has expanded in the future.