All language subtitles for PBS.Sinking.Cities.Tokyo.1080p.HDTV.x264.AAC.MVGroup.org.eng

-Very frightening moments
unfolding in eastern Japan

along the Kinugawa River.

-Japan has been pounded
with heavy rain

for two days in a row.

This is the 18th typhoon
to hit Japan this year.

-September 2015.

20 inches of rain pelts
down on Joso City

just outside Tokyo, Japan.

The river that flows
through the city

can't contain this
unprecedented rainfall.

The river floods,
and 65,000 people

find themselves
trapped in a watery nightmare.

♪♪

This, despite the fact
that Tokyo has the most advanced

flood prevention system
in the world.

-Japan is prone to so many
different types

of natural disasters,

including the flooding
and potential for mud slides

that we are seeing right now.

-But that system
did not anticipate

the changes
this century brings --

rising sea levels and stronger,

more frequent rainstorms
than have ever been recorded.

-[ Speaking Japanese ]

-Tokyo's defense line
is constructed to endure

a certain amount of rain.

The reality is the embankment

is not strong enough
to withstand such force.

-[ Screams ]
[ Helicopter blades whirring ]

-The world's great cities
face threats

they have never before
encountered.

New York.

Tokyo.

London.

Miami.

The threats come from the sea...

from above...

and from below.

These are the problems
and their solutions...

♪♪

...for when the water comes.

♪♪

-More than 170,000 people
received evacuation orders,

and we know dozens of them
were stranded in their homes,

even a man holding
onto a light pole

waving for the Japanese
military helicopters

to come and rescue him.

-From June to October,

an average of 20 typhoons
approach Japan each year.

But the typhoon that hit
Joso City in September 2015

was different.

The area had seen
stronger typhoons,

but never before had
the rain fallen so hard.

[ Birds chirping ]

[ Door closes ]

-[ Speaking Japanese ]

♪♪

[ Speaking Japanese ]

-This is the Kinu River.

In Chinese letters, the name
is spelled as angry demon.

-[ Speaking Japanese ]

-My father-in-law was also here.

He came with me
because he was worried.

And as soon as he said,
"Watch out!"

the water came rushing in.

-[ Speaking Japanese ]

-Hiromi Shinozaki
and her father-in-law

were among the people swept away
in the sudden deluge.

They clung to a floating piece
of timber to avoid drowning.

Torrential waters washed
everything away

in residential neighborhoods.

Hiromi was one of dozens
of stranded residents

rescued by helicopters that day,
as these people were.

-[ Speaking Japanese ]

-Holding onto the timber,
we hoped that as long

as our faces were above
the surface of the water,

we would be okay.

We held on as best we could.

But we weren't able to keep
a hold on it,

so we had to swim
for our lives.

-They finally made it to shore
where they were still trapped.

♪♪

[ Announcement in Japanese
over P.A. system ]

[ Siren wails ]

-[ Speaking Japanese ]

-People were stuck
and needed help everywhere.

They were waving to helicopters,
calling for help.

-[ Speaking Japanese ]

[

Helicopter blades whirring

]

-[ Speaking Japanese ]

-They were hovering above us.

One rescuer came down, but
because of the fierce current,

he got washed away.

-[ Speaking Japanese ]

-I tried to hold on in spite
of the strong wind.

It was really hard, but they
finally pulled me up to safety.

-Her father in law
was also rescued.

In fact, only two people died.

7,000 homes and buildings
in Joso City

were damaged
or destroyed in that flood.

Joso City was hit with
20 inches of rain in 24 hours.

If that much rain had fallen
on Tokyo, just 30 miles away,

the results would have been
even more catastrophic.

♪♪

Tokyo is the largest city
in the world

with 38 million people
in the Greater Tokyo Area.

Without this vital city,
Japan's economy would collapse,

which is why protecting
this city matters.

-Tokyo is like the Rolls-Royce
of city and engineering.

It has most of
the high tech system

that you can find in the world.

-Dr. Christopher Gomez
of Kobe University studies

the threat Tokyo faces
from the rising sea.

-Tokyo is the economic engine
of Japan,

and Japan is one of the major
engine of the world economy.

So all of this
is interconnected.

If you start to have
a major flood on Tokyo,

we're all going to pay it,
and very directly, actually.

[ Birds crying ]

-[ Speaking Japanese ]

-Many insurance companies
around the world,

such as Lloyd's or Swiss Re,

have assessed Tokyo

as the most dangerous city
in the world.

And in their assessment,

they say Tokyo's preparation
for flooding is not enough.

♪♪

-[ Speaking Japanese ]

-So the true risk to
Tokyo lies in people believing

that they are protected
and safe

when they are not at all.

♪♪

-Understanding Tokyo begins
with a picture

of the city's relationship
with the sea.

It sits on the shore
of Tokyo Bay,

which connects
to the Pacific Ocean.

To the city's East
is the Edo River,

and its western border
runs along the Tama River.

In all, 107 rivers
run through the city.

Water is the heart
and veins of Tokyo.

♪♪

Though some areas
are below sea level,

the city sits 130 feet
above it on average,

compared with New York
at just over 30 feet

or Miami at 6 feet,

Tokyo's higher ground
suggests relative safety

as oceans rise around the world.

But the difference with Tokyo

is the wide range
of threats it faces --

more than any other city
on the planet.

[ People scream ]

Earthquakes.

Tsunamis.

A unique quicksand phenomenon
called liquefaction.

And, above all...
[ Thunder rumbles ]

...powerful rainstorms
that come with typhoons.

Typhoons pound Tokyo with rain
from June to October every year.

The city gets 60 inches
of rain per year,

three times the legendary
rainfall of London.

But this isn't new.

♪♪

-32 inches of rain deluges
heavily populated Kyushu,

Japan's
southernmost major island.

Low-lying areas
where cities and towns

are concentrated
were hardest hit.

The record torrents brought

the island's streams
and rivers to overflow,

a surging tide of destruction

swept through the area
near Nagasaki,

leaving in its wake
a sea of mud, debris, and death.

-In the half century
since that 1954 deluge,

the heavy precipitation
from these storms

has become 30 percent greater

and more intense
than ever before

in the city's
recorded history.

In 2018, typhoon Maria
strikes Japan's southwest,

bringing the country's
worst flooding and mudslides

in 35 years.

Millions of people are
displaced from their homes,

throwing Japan
into a state of emergency.

Over 200 people are dead,

and the damage is estimated
in the billions of dollars

with roads, bridges,
and railways destroyed.

The people of Japan reel
from the disaster,

but fear worse is still to come

from even more powerful
typhoons.

-[ Speaking Japanese ]

-The behavior of the typhoons
around Japan in recent years

shows that they are
clearly different

from the ones in the past.

-Dr. Tomoya Shibayama has been
studying typhoons

and their rainfall
for nearly 40 years.

-[ Speaking Japanese ]

-Until recently,
it was common for a typhoon

to lose its intensity
as it got closer to Japan

because the sea surface
temperature was colder.

One of the recent changes
is that typhoons

continue to grow
as they approach Japan

because the sea surface
temperature is warmer,

so the typhoon does
not lose its power.

-Sea surface temperatures
around Japan are expected

to rise by almost
4 degrees Fahrenheit by 2100.

This means storms will increase
in intensity

as they approach
the island nation.

-[ Speaking Japanese ]

-Until now, we have been
referring to the Ise Bay Typhoon

as our benchmark.

-The Ise Bay Typhoon
is also known as Typhoon Vera.

In 1959, it hit Japan
with 20 inches of rain

and a 13-foot storm surge.

Some 5,000 people died,
and Vera did

over $2 billion of damage --

Japan's deadliest
and costliest typhoon.

-[ Speaking Japanese ]

-But in the future, I think
we need to be prepared

for even bigger storm surges.

♪♪

-Flooding is a problem
Tokyo has endured

for four centuries.

In the 20th Century
after Typhoon Vera,

the city found solutions
through elaborate engineering.

Water is diverted to rivers

through a series
of canals and pipes,

which all flow back
into the sea.

And the city's main rivers
are contained by levees,

which have been
built up over decades

to prevent flooding
in low-lying areas.

-[ Speaking Japanese ]

-The limit of the Arakawa
River's defense

is rainfall of 20 inches
in 3 days.

The levees are built
based on such a plan.

[ Helicopter blades whirring ]

So if the same kind of rain
that fell on the Kinu River

would fall on Tokyo,

I have to say
that the reality is,

the embankment is not strong
enough to endure such force.

-[ Speaking Japanese ]

-Tokyo is defenseless
against such rainfall.

-[ Speaking Japanese ]

-The moment the embankment
breaks,

a high wave, like a tsunami,
would hit residential areas.

♪♪

-Stronger, wetter typhoons are
just one of Tokyo's problems.

Another is tsunamis,
triggered by earthquakes.

Japan is situated
on the Pacific Ring of Fire,

a tectonic plate
that is responsible

for 90 percent of
the world's earthquakes.

Japan records more of them
every year

than any other country
on earth -- 1,500 earthquakes.

With sea levels rising,

the aftershocks of tsunamis
are deadlier than ever.

In 2011, an earthquake
triggered a tsunami,

leading to meltdown

at the Fukushima Nuclear
Power Plant.

The tsunami set off the worst

nuclear disaster
since Chernobyl,

and it woke the world up to the
constant danger Japan faces

from the sea.

-[ Speaking Japanese ]

-People realized that they had
to recognize

the destructive power
of the water.

If the river embankment
in Tokyo breaks,

residential areas
would be hit by waves

as large as the tsunami
which destroyed Fukushima.

[ Helicopter blades whirring ]

♪♪

-The 2011 earthquake did impact
Tokyo 150 miles away.

Yoshitaka Udagawa owns
an exotic fish shop in Urayasu,

a city on Tokyo's outskirts.

-[ Speaking Japanese ]

-I felt a massive jolt
with a giant thud.

We have many earthquakes
in Japan,

so I thought,
"It's an earthquake again."

But I had never experienced
such an intense earthquake.

It continued, "Boom! Boom!
Boom!"

-Udagawa fled his store,

into the street
and the earthquake's fury.

♪♪

-[ Speaking Japanese ]

-It was difficult to walk.

The poles were really swaying
in all directions.

The ground was shaking.

-[ Speaking Japanese ]

-I continued walking

and heard a noise
when I got to this point.

You see that dark part
over there?

There was something shooting out
of it like oil blowing out.

-[ Speaking Japanese ]

♪♪

-The water's gushing out
everywhere.

The ocean seems to be coming up.

-The dark liquid gushing
from the ground was not oil,

but water and mud.

A process called liquefaction
was causing the groundwater

to push up to the surface.

About 10 percent of Tokyo
is built on low-lying sediment

along the city's coast.

The shaking effect
from the earthquakes

creates a form of liquid earth,
like quicksand.

Liquefaction is now
a regular side effect

of earthquakes in Tokyo.

-Under your feet, you have up
to 125 meters of soft sediment

mixed with water.

The problem with it is

that mixture between
water and sediment,

each time you have a shake,

the water get expelled
from the ground,

so it leaves hole in the ground
in some ways,

and then the ground goes down.

♪♪

-Shinji Sassa of the Port
and Airport Research Institute

created a shake table
to demonstrate

the process of liquefaction
in the laboratory.

♪♪

-3, 2, 1...

Okay.

[ Table whirring ]

-So when you look
at the map right here,

you can see that
all the blue areas here,

this is already below sea level.

We are minus one,

minus two meters
below sea level.

And Tokyo is not any other city.

You have a major quake
waiting for you,

so all of that can actually
go down by an extra meter.

What you have to remember

is that all the sediments
below the city,

a lot of them are a mixture
of water and sand,

and once all this gets excited,
you get liquefaction.

The water comes out,

and what remains
is the land going down.

-Liquefaction is a new
phenomenon in Tokyo.

It, too, is linked
to the rising sea levels.

-The groundwater of Tokyo
is connected to the sea level,

so if the sea level goes up,

then the groundwater
will also go up.

It's like a pie chart --
we have been dividing that pie.

So those slices can be
the river floods.

Another one can be

the liquefaction
during an earthquake

that brings the land down.

Another one
can be the storm surge.

Another one will be, again,
the sea level rise.

And all of those elements that
are looked on separately

will, at some point,
happen together.

♪♪

-Tokyo has one last
unique problem.

Entire neighborhoods are
slowly sinking below sea level.

Decades of pumping ground water
for domestic use

has left massive cavities
below the city's foundations,

and some areas are now sinking.

-100 years ago,
Tokyo was just a village,

just a few people,
called Edo, actually.

And during the 19th Century,
this village became the capital.

So on top of the marshlands,

on top of silty sediment
mixed with water,

they started to drain this land
and build this huge capital.

But it means that underneath
the ground,

you still have the mud flats.

What you have below your feet is
a mixture of water and sediment.

Until the 1960s,

people used to drink water
from the ground water,

meaning that they pumped
the water out of the ground.

So where the water was,
then just a void remains.

So the land sinks slowly.

-30 percent
of Tokyo's population

now lives below sea level,

and some homes have sunk as much
as 15 feet due to subsidence,

the caving in of land.

As sea levels rise,

the gap between
these low-lying neighborhoods

and the waters above them
becomes ever more dangerous.

-[ Speaking Japanese ]

-The sea level rise is now
producing the same effect

as the ground subsidence.

-[ Speaking Japanese ]

-The danger is getting
greater and greater.

-[ Speaking Japanese ]

-You have a city which is just
at the zero level,

so any increase in sea level
is already a problem.

So this map here
is the map of Tokyo.

So what you can see
in the white here

is the bay where the water is,

and everything else
is supposed to be land.

But if you look at it,

you can see
that all the blue areas here --

and they are blue
for a good reason.

It's because it's already
below the sea level.

If you add 50 centimeters
of sea level,

you can see
that a large part of the city

already,
in red here, is under water.

And then if you add
75 centimeters and one meter,

you almost have 100
square kilometers of water

covering your land.

-If the sea rises by 3 feet,

60 square miles
of Tokyo will be submerged.

Japan's problems are compounded
by an economic challenge.

Its population is expected
to shrink by a third

in the next half-century.

In the past, a growing
population and a booming economy

helped pay for megaprojects

to prevent and combat
natural disasters.

Those days are ending.

40 percent
of Japan's population

is projected
to be over age 64 by 2050.

The country's birthrate
is plummeting,

and it isn't expected to rebound
to present levels

for another 45 years.

-So, Japan has been very good
at facing its issue so far.

They've been working very hard
on all of this.

You have a lot of engineering
systems that are top notch.

But in a country
where the population

is increasingly aging

and where money's going to be
scarcer and scarcer,

how do you maintain
all the system?

The population, which is aging,
plus the climate change

is a real
ticking bomb for Tokyo.

How do you build new dikes
and new levees

when you don't have
the fund for it?

So it's a real challenge.

-Kamaishi is 350 miles
up the coast from Tokyo.

It's an extreme example of
Japan's plummeting population.

Less than 40,000 people
live here,

25,000 fewer than in 1980.

The city is home to the
largest seawall in the world.

-[ Speaking Japanese ]

-The north wall was 3,200 feet.

The southern wall
was 2,200 feet,

and the part where the ships
go through was 1,000 feet long,

so as a whole,

it was 6,500 feet --
over a mile long.

-[ Speaking Japanese ]

-Kamaishi's breakwater
is constructed

at a depth of 200 feet
below the surface.

It's in the Guinness Book
of World Records.

-The breakwater cost
$1.6 billion

and took three decades
to complete.

In 2009,
the job was finally done.

[ Sirens wail ]

Just two years later...

-[ Shouts in Japanese ]

[ People scream ]

-...Japan's tsunami crushed this
marvel of engineering like a toy

and swept through the town.

The bodies of about 1,000
people were never found.

[ Birds chirping ]

Akiko Iwasaki runs a hotel
outside Kamaishi.

She witnessed the horrific
32-foot-high tidal flood

that destroyed her city.

She was also personally struck
by tragedy.

One of her relatives
was among those killed.

-[ Speaking Japanese ]

-One of my family members
tied herself to a pillar

at the entrance of her house
with a rope.

She was a senior,
and when the firefighters

urged residents to evacuate,
she probably didn't think

the tsunami
would come up that high.

She didn't run away.

When she was found,
her son said that,

in the time she took
to tie herself to the pillar,

she could have run
to safety.

♪♪

-[ Screams in Japanese ]

-Sadness turned to outrage.

How could this expensive
megaproject

that was built
to protect the city

fail so catastrophically?

The seawall
is now being rebuilt.

And how to make it certain
not to fail again

is Yussai Itoh's job.

-[ Speaking Japanese ]

-Since we're in the midst
of construction,

we see some different heights.

However, they will be covered
with concrete,

and they will all be level.

The tsunami came from offshore,

crossed the mouth
of the bay breakwater,

and moved into the city.

It was about 33 feet high.

-[ Speaking Japanese ]

-The seawall had been designed
to withstand

a wave of that height.

The engineers who designed
the seawall

were determined to figure out
why and how it failed

with such loss of life.

-[ Speaking Japanese ]

-Before the tsunami
in Northeastern Japan,

we didn't understand exactly
how barriers were destroyed.

♪♪

-In his hydraulics lab
at Waseda University,

Dr. Tomoya Shibayama is trying
to solve the mystery.

-[ Speaking Japanese ]

-This is the simulator
for the waves

caused by the tsunami
or the storm charge.

From the back of this waterway,
the storm charge comes this way.

This structure here
simulates the breakwaters.

The waves go beyond
the breakwater

and reach the towns near Tokyo.

We observe how the water behaves
in this area

using this hydraulic simulator.

♪♪

-Using the simulator to recreate
a storm surge,

Shibayama
and his research assistants

record it
on a high-speed camera.

A colored dye allows them to see
the water's behavior in detail.

-3, 2, 1, go.

-Once the experiment
is complete,

Shibayama can look at the data
collected by cameras and sensors

to determine the water's motion
after it hits the barrier.

He concludes that the storm
surge washed over the wall,

putting weight on the top,

and then dealt
a vicious backwards blow

to the support structures
underneath.

-It gets really fast here.

We must check
the velocity field

and pressure field.

[ Metal clacks ]

-Once it gets past
the breakwater,

powerful vortices push and pull

at the concrete
in all directions

with a force the wall's
designers did not anticipate.

Still, some experts believe

that even Japan's most
advanced engineering

is no match for
the increasing power of the sea.

-The hard solutions that people
talk about --

various gates, levies,
walls, and so forth,

I'm not sure it's practical

because sometimes,
it's just not clear to me

that the science is there
that says

it's really gonna do the job
it's meant to do.

-Vishaan Chakrabarti
is a New York architect

specializing
in storm resilience.

-It's a basic
Albert Einstein thing.

Matter doesn't just disappear.

The water just doesn't magically
go away when you build a wall.

It gets redirected
to someone else's doorstep,

and I think that's
a fundamental issue that,

again, I can't solve
as an architect.

I think most people who deal
with this can't really solve.

-No wall is fail-safe.

So I think it does
tend to encourage people

to live behind the wall
in a way that's not resourceful,

in a way that trusts the wall
to never fail.

And, uh, that's not good.

-Urban designer
Kristina Hill warns against

what in her specialty are called
"hard solutions."

The water always wins.

-When you build a wall,
you size the foundation

for the height of the wall.

If you -- you can't just add
more bricks to the top

and have it be
structurally sound.

So future generations,

if that's not big enough,
have to actually replace it.

-Dr. Shibayama also knows
no seawall is invincible.

The revised plan is not to build
higher or even stronger.

Rather than try to deflect
the storm surge,

the new breakwater is designed
to absorb its energy

and in extreme cases
allow water to flow over top

without ripping it apart.

-[ Speaking Japanese ]

-The role of such hard
structures as breakwaters

and tsunami storm surge walls
isn't a complete defense,

rather, as with
the case of Kamaishi,

they delay the storm's impact
by reducing its energy.

-[ Speaking Japanese ]

-What we need to change
moving forward

is that we are in the era
in which each one of us

must think about
how we are going to survive

and how we are going
to protect our families

even if water
goes over hard structures.

♪♪

-Typhoons, tsunamis,
earthquakes,

rising seas, liquefaction,
sinking neighborhoods.

Tokyo, the world's most
populous city,

has the world's largest
set of problems.

-So when you pile up all of
those elements together --

so the sea level will rise
one meter, plus the quake,

that's two meter.

Plus, eventually, a typhoon
that can bring the water level

a meter higher,
so that's three meters.

And if you are unlucky
at that time

that you have flood
from the rivers

or you have a small tsunami

that are predicted to be
between 1 and 1.5 meter,

all piling
those elements together,

well, you're in deep trouble.

It's not a question
of is it going to happen.

It's a question of
wh

en

it is going to happen.

♪♪

-Nonetheless, Tokyo may be one

of the very few cities
in the world

seriously grappling with
the challenge of climate change.

It's figured out
engineering solutions before,

and with sea levels rising,
Japan now needs to do it again.

In 1993, before climate change
was much discussed,

Tokyo decided to tackle
its existing flood problem

with a megaproject
that many believe

was decades ahead of its time.

♪♪

♪♪

Japan built a futuristic cavern
to protect itself against water

from above, below,
or from the surrounding sea.

-[ Speaking Japanese ]
-We are in the surge tank.

We have come down
to 65 feet the ground.

On the left hand side
is Shaft #1.

Further down the tunnel,
we also have Shaft #2, 3,

4, and 5.

The overflow from flooding

is collected
through these shafts

and goes through the tunnel

to come up through Shaft #1
gradually.

-[ Speaking Japanese ]

-The water then flows

into the Showa Drainage
Pump Station

through this surge tank.

-[ Speaking Japanese ]

-When water floods Tokyo,
this is where it all goes.

-[ Speaking Japanese ]

-The accumulated water
will rise,

and eventually,
it will reach a certain level.

Then, it gets forced
through the four pumps

of the Showa Drainage
Pump system

to be drained out
to the Edo River.

-[ Speaking Japanese ]

-We have the water flowing
into our facility

about seven times a year
on average.

Out of those 7 times,

for about 60 percent
of the time,

the water flows into here

and is forced out
to the Edo River.

For the remaining 40 percent
of the time,

we store the water here

as it can hold
up to 670,000 tons,

and then the water gets returned
to the river it came from.

-The system can hold up
to 65 million gallons of water

and can pump it out
as quickly as it comes in.

Lewis Makana
is a UK-based engineer

focused on the problem
of storm water management.

-For the mind's eye
to capture the scale

and size of these silos,

you can take
the Statue of Liberty

and place it inside
one of those silos.

That's how big it is.

It's quite impressive.

Flooding in Tokyo
is a big challenge.

If they didn't have
that type of protection,

they would be gone.

♪♪

-[ Speaking Japanese ]

-It took 13 years to construct
this facility --

from 1993 to 2006.

In actual figures,
it cost 230 billion yen.

-That's more
than $2 billion.

-Some domestic and international
evaluations

consider this to be expensive.

However, the flood damages
in this region

have been reduced
to approximately one-tenth.

Therefore, I think
it is not that expensive

when you take the flood
damages into consideration.

-In 2015,
after a record rainfall,

this temple to engineering
was filled to the brim.

But the heaviest of those rains
missed Tokyo,

with the greater impact outside
the city to the northeast.

Kuniharu says the giant
Showa Drainage Pump system

could not have coped if that
storm had directly hit Tokyo.

-[ Speaking Japanese ]

-I heard it was the greatest
amount of inflow and drainage

since this facility began
its operation.

Our facility has four pumps,

and we usually use
one or two at a time.

2015 was the first time
all four pumps operated

at full capacity simultaneously
for more than a week

to drain the water
in an effort to mitigate

flooding in the region.

-Once the tank is full,
it drains into the Edo River

at a rate of 53,000 gallons,

the capacity of an Olympic size
swimming pool,

every 12 seconds.

It's the most advanced flood
mitigation system on the planet.

But recent record rainfalls
are too much

for even the massive
reservoirs to handle.

-[ Speaking Japanese ]

-We do get questioned
about what happens

if we had a rainfall
of a similar scale,

and we must admit
that we are not fully certain.

To build a facility
in the first place,

there is an expected amount
of water that will flow into it.

This facility was designed
to cope with that amount.

But if there is a rainfall
or water flow

that is above this upper limit,

we will not be able
to take it in nor drain it out.

It is unavoidable
that the local communities

will pay the price
in such a case.

-With increased rainfall
and rising seas,

engineers like Dr. Makana
believe

the facility is no longer
100 percent effective.

-Even with this amazing
superstructure,

they still recognize that
because of climate change,

because of the rising sea level,
and because of the potential,

using scenario modeling

and looking
at the worst-case scenario

of what potentially could be
the worst-case type of tide,

tidal surge, in addition
to maybe a typhoon event,

they recognize this protection
that is currently in place

will not be fit for purpose.

That will be something for them
to discuss and feature

in their future
planning for Tokyo,

but it will need
to be put in place,

or else Tokyo will be submerged
by flooding.

[ Water sloshes ]

♪♪

-Tokyo is protected by a series
of 44 flood gates

along the city's many rivers.

They are designed to stop storm
surges as high as 26 feet.

The highest ever recorded
in Tokyo is only 10 feet.

♪♪

-[ Speaking Japanese ]

-In the event of tsunamis
or storm surges,

we are supposed to close
the gate

when the water reaches
a certain level.

-Even with sea level rise,

the floodgates offer
substantial protection

to over a quarter of Tokyo.

-[ Speaking Japanese ]

-You see that there are seawalls
all around the gate,

and the walls look high.

But inside the walls,
it's actually fairly low.

So if we don't close the gate,

the area inside the walls
would be submerged.

-If the water overflows
the riverbanks,

pumping stations are activated.

-[ Speaking Japanese ]

-When the water level
on the inner side

of a closed water gate
rises with rain,

you use this pump
to move the water

accumulated inside the gate
to the other side of the gate.

-[ Speaking Japanese

♪♪

-The next line of defense

is what's called super levees,

which are currently being built
all around Tokyo.

Dr. Kristina Hill believes
the levees are Japan's

best long-term solution
against the rising sea.

-What they did was they piled up

all this earthquake-safe
material,

so that means carefully
sorted gravels and sands,

um, and then they extended
everybody's property lines

up into the air
through that new material,

and gave
the original property owners

rights to redevelop
buildings on top

that now have water views
in some cases.

So I think
it's a fantastic idea.

Even if the dike is overtopped,
if water comes over the top,

they've built terraces
on the backside

that should slow that water down

as it moved towards
highly populated areas in Tokyo.

So important
to slow flooding down.

-Nobuyuki Tsuchiya
is lead engineer

on the super levee project.

-[ Speaking Japanese ]

-With the ground subsidence,

we had to reinforce the levees
by adding height.

That's why this one looks
a bit steep.

When it was originally made,
it was more gradual.

Because we added the height,
it's a bit unbalanced.

-[ Speaking Japanese ]

Because it's such
a serious problem,

we've been working on
this super levee project,

which would make this
residential ground

as high as the levees

and defend the community
from water.

-[ Speaking Japanese ]

-The super levees
were planned to run

for 540 miles along 6 rivers
to a height of 30 feet.

But that plan was so expensive,
it was scaled down to protect

only the most vulnerable,
low-lying areas.

Still, it comes at a cost
to Tokyo's landscape

and for residents who
have to leave their homes

as their entire neighborhoods
are elevated.

-And then we fill the land
and raise the ground level.

Then we build roads, parks,

and rebuild
the town from scratch.

Then the residents
can come back.

♪♪

-The people of Tokyo
have come to realize

that they have few good options.

It's either evacuate
for a short time for rebuilding

or abandon their homes for good.

-It's going to be challenging,
but if this levee breaks,

it's not only these houses
that get destroyed,

but also the water would overrun
the whole Tokyo area.

If you think about that,
then asking for some cooperation

and time from the residents here

would make the most sense
for the safety of Tokyo.

-[ Speaking Japanese ]

♪♪

[ Siren wails ]

♪♪

[ Birds crying ]

-Tokyo has to seek
a whole array of solutions

and keep re-engineering itself

for a future of rising seas.

-So the coastal defenses
in Tokyo

are some of best in the world

by a long range.

And Tokyo City has been
rising up their differences

to meet those challenges.

Does it mean that
it's going to be enough

for the future challenges?

That's another question.

-The city may have to consider
ideas from outside of Japan.

Kunlé Adeyemi is an architect
whose focus is on building

near, and even on, water.

Faced with climate change,
he believes

humanity has to adapt its
thinking before it's too late.

-I am a realistic optimist.

[ Laughs ]

And what I mean by that

is that I'm realistic
in the sense that,

you know, I go to Tokyo,

and I see the impact
of sea level rise,

climate change, or simply water.

I just see places
that used to be land

are now covered by water.

That is the real fact.

I don't want to see that
as a problem.

I want to see that
as an opportunity.

And how do I deal with this
opportunity

where I have to learn
to live with water

as opposed to fighting it?

And that's what I see --

we're producing infrastructure
for water culture.

-Adeyemi has proposed
an experimental design

for temporary,
low-cost floating habitats

that can be used for housing,
office space, or schools.

-Well, so, the idea is that
we're trying to create

a building system

where the components
are easy to fabricate

in any kind of local region

and assemble.

No matter where you are
in the world,

you can find
a particular class of timber

that will be suitable for
the production of the structure.

-Adeyemi's design has been
considered for several cities,

including Tokyo.

It can easily be adapted
to Tokyo's unique environment.

Temperatures
rarely drop below freezing,

and the structure can be made

to ride out
heavy rains and waves.

-We've used two systems so far,

the first being just very basic,
recycled plastic barrels

that are used
in industrial areas

and second, has been uh,
the expanded polystyrene,

which is used in construction.

We know there are
different technologies

for creating floatation devices

that would enable this to work
in different parts of the world.

♪♪

-Engineer Toshio Nakajima has
an even more ambitious idea.

He's proposed an entire
floating city in Tokyo Bay.

-[ Speaking Japanese ]

-The concept
of this floating city

is to make the lowest land
as safe as possible.

So we dig it out to make
the low land even lower,

and then we flood it.

After putting the water in,

we build
the floating foundation,

and we live on it
so that when it rains

and the water level goes up,

the city itself is raised
with the water

and protects itself
from water disasters.

-Nakajima based his design
on the Mega-Float --

a floating airplane runway
in Tokyo Bay --

that has proven
to be very effective.

Nakajima's city would use
the same technology,

basically a gigantic
modular floating dock.

-[ Speaking Japanese ]

-This water is taken
from the Arakawa River,

and the water
goes through the city

and goes out into the sea.

So the city controls the water.

-[ Speaking Japanese ]

-The energy we need to move
the water through the city

is generated in this area here
by using the solar panels.

-[ Speaking Japanese ]

-We would have a big tank
underwater,

located below the city,
to store rainwater, too.

-[ Speaking Japanese ]

-We won't need anything
difficult technology-wise.

If we're serious about it,
we can build it anytime.

-Nakajima's floating city
would look

something like
this video simulation.

It would be able to withstand
sea level rise, storm surges,

and extreme rainfall.

But Tokyo's
cash-strapped government

has not approved
the plan so far.

-I think it's not only Tokyo,
but in all of Japan,

people want to keep
their conventional ways.

-[ Speaking Japanese ]

-I have the impression that many
people are conservative

and not open to new ideas.

-Tokyo has to survive
the rising waters.

The future of Japan
depends on it.

Yet that may mean
reshaping the city

by retreating from the areas
in the greatest danger.

-One of the cheapest solution
and one of the easiest solution,

at least on paper,
might be the retreat

from the most
floodable areas of Tokyo.

[ Thunder rumbles ]

-By the end of the century,

Tokyo's world-famous
Shibuya district

could be one place
to be abandoned to the waters.

-We're going to see
the population shrinking,

so less people in the city.

And that's maybe a chance

to remodel the city
in which we live.

How can we concentrate people
in safe areas

and abandon slowly and naturally

areas that are
too dangerous to live in?

-I think the question's
not just about

whether we retreat
or we stand our ground

because that sets
this opposition

between humanity
and the environment.

It's a reconsideration

of how to ensure
that there's coexistence.

So there needs to be a balance,

and I think where we've always
created walls

between us and the environment,

now we need
to let go of the walls

and find new ways
of bridging the gap.

-Some believe solutions may be
rediscovered from history.

"Resiliency" is now a buzzword

of climate change engineering
and design.

But it perfectly describes
what the people of Tokyo

have been doing for centuries.

-[ Speaking Japanese ]

-Our ancestors made the city
here on a low, flat land,

good for agriculture,
and developed the city.

-[ Speaking Japanese ]

♪♪

-People learned
to live with the water

when there was flooding.

It's like a city in the water.

In order to live there,

people made
their residence higher.

We call it constructing
a "Mizuya" or "Mizuka,"

a shelter from the flood.

But when you go to work,
you go on a boat.

-[ Speaking Japanese ]

-When the water recedes,
you just hang your boat

under the floor of your house.

So people lived flexibly
with the water.

It was not about fighting
the risk,

but predicting it, accepting it,
and living with it.

-Tokyo is facing a huge amount
of challenges,

but people are still here,
rising to those challenges.

And the way they look at it,
human beings are part of nature,

part of the environment.

Those hazards and disasters

also part of the environment
we live in,

and we have to be able
to live with it.

-Those who lived through

the most recent disasters
to strike Tokyo

are still adapting
to their changing world,

but they know
they face challenges

previous generations never did.

-[ Speaking Japanese ]

-It's over there.

This is the manhole
that popped out of the ground.

It's left as a monument.

This is it.

♪♪

It got pushed up
out of the ground.

It reminds me
that this happened,

and it makes me think

that we don't want
something like this again.

My view now is that
this is a place to pray

for no more disasters.

-Despite his prayers,
sea levels continue to rise,

typhoons grow stronger,
and it rains more than ever.

-[ Speaking Japanese ]
-Yes.

I'm worried so much
that I can't sleep.

That's why at this moment, too,
we're trying to defend the city

as much as possible
against the water.

-[ Speaking Japanese ]

-We're building super levees,
strengthening seawalls,

improving pumping stations,
and so on.

-Human beings need
to see danger.

They need to know the world
they live in

in order to become
more resourceful over time.

We have a long haul here
with climate change.

It's not going to be over
in 50 years.

We need multiple generations

to become courageous
and resourceful

and smart with their money
and technology

and care about each other.

-With today's level of funding,
today's engineering,

there is no clear answer

on how to engineer our way
out of this problem.

But we're thinking about
50 years',

100 years' time from now.

And the engineering systems
are going to progress, as well.

Nobody can tell
what kind of solution

we're going to be able to create
or build in 100 years.

-I would definitely say it is
the Godzilla of all problems,

and I believe a lot of
the problems we are facing

from climate change will require
engineering-led solutions,

and whether an engineer
can take on Godzilla

is what we are
trying to find out.

[ Laughs ]

-It scares the bejesus
out of me.

Living near the water, I think,

is something that is so core
to the human spirit.

And even people who don't
live near the oceans,

they go to lakes,
they go to rivers.

I think this is just --

we come from water as a species.

And so I just...
To me, it's just so tragic,

the idea that we now have
to think of water as the enemy.

What we have right now
is we have a tool kit

that can help us make things
better in the short term.

That's only
going to buy us some time

as we figure out this problem
on a global level,

but it's at the global level
that it has to be figured out.

-Engineers, planners,
and civic leaders in Tokyo

are addressing
their epic challenge

with technology,
engineering, and imagination --

seeking solutions to protect
the city for decades to come.

-[ Speaking Japanese ]

-Tokyo is trying to keep
the water away

because it's being conventional.

They're trying to fight
against the water.

But we can't keep doing that

because the water is something
more powerful than us.

There's no way we would win.

-The more we learn
to evolve and adapt

to what seems to be,

at least in the next 50,
100 years, the path,

the better we are in creating
more livable environments.

And I think the human species

is an incredibly
intelligent species,

and Tokyo will learn
to live with water.

-[ Speaking Japanese ]

-Even though we have been
trying our best,

I don't think we can say

that we are fully prepared
for disasters.

♪♪

-Next time
on "Sinking Cities,"

London has been plagued
by flooding for centuries.

-London probably has
one of the longest

flood histories of
anywhere in the world.

-They built the Thames Barrier

and believed flooding
was a thing of the past.

Now a city that thought
it was safe

is facing a new reality --

sea levels are going up.

-A thousand properties
got flooded

not from the tides, but the sky.

-You could get
such a severe weather event,

it could overwhelm our defenses.

[ Indistinct conversations ]

♪♪

-To order "Sinking Cities"
on DVD,

visit ShopPBS or call
1-800-PLAY-PBS.

This program is also available
on Amazon Prime Video.

♪♪

♪♪