Typhoon victims felt worst was over; then floods came

Sadly this is the one problem that will always occur following storms of this size. Not to mention that the only places people can build their homes in these areas are on natural flood plains.

Preventing floods like these from happening is next to impossible.

Time to stop building so close to rivers...

Alas, most residents that live in natural floodplains in Japan have no objective idea of how bad the flooding can get. They can only depend on their own experience. There certainly are resources available, but not readily available.

Indeed, many cities are loath to publish flood maps because of the implications for land prices, etc. Or, in many cases, they may not actually have such things.

At least, that is my understanding.

Preventing floods is impossible. However, it is possible to rebuild on stilts above previously known water marks.

"warmer-than-usual sea temperatures"?

I'd like to know their source of data. The current sea surface temperature is below average.

https://www.seatemperature.org/asia/japan/tokyo.htm

Time to stop building so close to rivers...

There was talk of communities relocating to higher ground in Tohoku after the tsunami. Did it happen or were the communities rebuilt in the same place?

Houses built on stilts means stairs, which are bad for old people. If the flooding risk is that high, it's probably best to move to higher ground.

If the flooding risk is that high, it's probably best to move to higher ground.

Even moving to higher ground poses risks, like landslides. But perhaps there should be a legal limit distance from the river where houses are allowed to be built. This will only happen more in the future so we need to come up with some solution.

With Climate Change, this is the new norm.

The flooding from Chikumagawa went several kilometers inland, distance from the river probably doesnt matter so much. Stilts means stairs... But almost all houses in Japan are at least 2 stories high, so old people will have stairs regardless. Plus there are lifts and those wheelchair lifters to help you get up stairs like that.

Previous articles state that about 7 dams would be releasing water during the typhoon. Was this action attributable to the water level? I think an incremental dam water release days prior to the typhoon making landfall could have been a help. The video of the devastation is unprecedent and I hope for the best possible outcome for everyone affected.

There was talk of communities relocating to higher ground in Tohoku after the tsunami. Did it happen or were the communities rebuilt in the same place?

no, of course it didn’t happen. And it’s frustrating because the government has spent millions of dollars trying to rebuild some of those towns they were destroyed by the tsunami, but it’s only a matter of time before they get wiped out again whether it’s a tsunami or a normal flood.

Previous articles state that about 7 dams would be releasing water during the typhoon. Was this action attributable to the water level?

Minimal. They were releasing water in order to prevent the dams from collapsing entirely.

Normally they adjust the amount of water that released to prevent flooding, but in this case the rivers would have overflowed regardless.

Japan needs to reinforce river embankments with cement pillars, driven deep in the ground.

My prefecture completed that years ago. It's on the the Shinanogawa.

The engineers placed the many pillars on the weak river stress points.

This is similar to what we did, thinking that we would just wait for the ongoing alerts to let us know when to go to higher ground. Probably not a good idea to do next time. Luckily the rivers near us didn't breach. We live 5km from the Arakawa which was really high and just 1km from a smaller river that was threatening to breach just 2.5 km up river.

Time to stop building so close to rivers...

That would make most of the Kanto plain uninhabited, except for the hilly parts downtown. According to google, we live 6-9 meters above sea level which is 3-6 meters above the roads next to the rivers that would flood. Not much leeway.

Do people in Japan sandbag dike during typhoons or potential flooding situations? I just saw people tape board up windows (With cardboard!) in Tokyo that is about it but I figure Sandbags might have helped a few places?

How about claiming 25 meter along the levee and make a 2nd levee but of lower level ? This way if the river go past the first one it is still blocked. \in between the levee they can put : road, fields, play gound, sport facility, ... .

They could even try wavy levee, I wonder if that could not help canalizing water by orienting it if the first levee collapse. The water force will be send back to the water coming, so perhaps that can reduce the force send against the 2nd levee. They will obviously be crazy splash and wave but this amount of water going past the levee should be better than the levee collapsing. I do not know if wavy levee was ever tried somewhere.

How about claiming 25 meter along the levee and make a 2nd levee but of lower level ? This way if the river go past the first one it is still blocked. \in between the levee they can put : road, fields, play gound, sport facility, ... .

First, while ideas are great, the problem is risk assessment and probability of need to justify the costs involved with taking what is mostly private land, to build these levees.

Does an event that will possibly only happen once every 100 years, justify the costs?

Easy to answer this after the fact, but this is the problem here. Prior planning does not exist, people forget, and history repeats itself.

Case is point, if the people had not built their homes, schools, and businesses in the path of the tsunami those lives would have been save right? But they and the people that run those districts, forgot the warnings that generations ago were placed as warnings for future generations.

People will talk about these measures, nothing will happen, and maybe in a generation or so, it will happen again, maybe sooner, maybe later, but it will happen!

Firstly,

I wish to express my deepest dymathy and condolences to all those affected by the typhoon and flooding, it looked terrible and brought back awful memories of the massive earthquake and tsunami.

Secondly, I could not find any reference to my PM (Scott Morrison) of Australia, expressing condolences to the people of Japan and offering money and help.

That is disgraceful, I am ashamed!

I keep thinking of mister Saito checking to see if there was flooding outside his home after the storm past his area and he said there was no water. I have done the very same thing during a category 2 twice, the difference is I live on a manmade lake that is fed via the river by ocean water. My backyard has a 50 foot incline that floods during the hurricane, which is no problem, because it has not reached the house. The devastation of this typhoon is shocking, at how long a distance the water traveled and how high the water level is after the storm had left the area possibly hours earlier.

Now for my cunning plan to help avert and/or reduce damage by flooding, for those living in a flood plain.

Build houses etc on strong steel and cement pylons, so the house is one storey above the ground. Cars could have ramps up to that level, or park in a carpark for local residents, again one storey above ground level.

Costs; it would be a financial benefit to councils, insurance companies and government in damages savings alone.

It would also reduce trauma and hardship to those affected.

So, governments could contribute by removing taxes and making financial donations. Insurance companies and councils could waive fees until the houses are built

I AM personally very sorry. Somethings must be not functioning in Japan.

Build houses etc on strong steel and cement pylons, so the house is one storey above the ground. Cars could have ramps up to that level, or park in a carpark for local residents, again one storey above ground level.

One building houses on stilts in a country that is prone to massive and frequent earthquakes is not the safest idea in the world. The costs to building such a house would be exorbitant.

Costs; it would be a financial benefit to councils, insurance companies and government in damages savings alone.

Costs would not benefit anyone but the construction companies

So, governments could contribute by removing taxes and making financial donations. Insurance companies and councils could waive fees until the houses are built

Governments remove taxes? You gotta be living in Utopia to think that any government would remove taxes. and there is no way any of these businesses or corporations are going to stop collecting profits to allow a person to build a potentially unsafe house or building.

Governments remove taxes? You gotta be living in Utopia to think that any government would remove taxes.

Not really. It is well know that when some government want their people to spend money on house improvement they made it so that it can be partly deduced from income tax : solar panel, two layered glass for windows, ...

Build houses etc on strong steel and cement pylons

On this one, I thought more of boat like house. Having house on some pillar, not one level high with anchor end if water were to rise releasing the house. But that is not suitable to all area. Still should be a option to study.

People will talk about these measures, nothing will happen

Perhaps stuff will happen. Everybody is not the same. It is why politics is important because sometimes you got lucky and elect someone which care.