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

♪♪

-Summer 2016, Canning Town,
East London.

-I was sitting here,
just working away,

and it was raining,
so I went outside

and opened the door, had a look.

I thought, "My God,
this is tropical."

It was a lot of rain.
[ Rain pouring ]

You know, you just don't see

that kind of rain
here in London,

and the water
just started coming in.

It was crazy.

In over two hours, there was
almost a meter of water in here,

sewage everywhere.

Drum kits were floating
about in the water.

Amps was just under the water.

Things that survived
were things that are on tables.

The roads were impassable
because the roads flooded.

The trains couldn't run because
it was basically a stream.

The amount of water that was
falling filled all the sewers,

and the water is going
to find its lowest point

below ground level here.

At the end of the day,
how can you cope?

-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.

[ Waves crashing ]

-So, underneath here is

the pump chamber with the pumps.

I know for a fact
it's going to happen again.

It will happen again.

It's just a matter of when.

Rebuilding it took
a good 10 months.

God forbid it should happen
like that again

and for some reason
the pumps don't work.

If it happened again,
I would just pack up.

-Flash flooding has become
commonplace in London.

In 2007, one incident left 1,400
properties in the city flooded.

-There's so much regeneration
going on in London

at the moment where any kind of
open space has been built on,

so where does
all that rainwater go?

It's not being soaked
into the ground anymore.

-London faces three challenges.

Summertime rainfall in the UK

has increased 20%
in the past decade.

The city is densely developed

along the Thames River
floodplain,

meaning all that rain
has no place to go,

and the legendary Thames
is handling more water than ever

as sea levels rise
all around the island nation.

The Thames has always been
at the heart

of London's prosperity,

linking the city
to the outside world,

but it has also posed a threat.

-London probably has one of
the longest flood histories

of anywhere in the world.

There's records of events
going back thousands of years.

I mean, there's hundreds of
major storms that have occurred

that have killed
several thousands of people.

-London has a population
of eight million people,

and the initial city
was designed

for four million people,

so it's actually doubled
over the course of,

we could say, 125 years.

If London stops functioning
and London is flooded,

this country, as far as you know
it, will stop functioning.

-While the Thames is widely
thought of as London's river,

it's actually part
of a 215-mile-long series

of tributaries and wetlands
throughout southeastern England.

The Thames flows east
from Greater London

into the North Sea
50 miles away.

Robert Muir-Wood is a resiliency
scientist in the private sector.

-So what we're looking at here
is a map

of the Greater London area,

and at the western end here,
we have the river,

which comes in
from the countryside

to the west of London,
comes in,

and the river
is getting wider now.

You can see it's also getting
a bit muddier

because the tides
are very strong.

They're carrying a lot of mud
with them,

swings around here and passes
into the Westminster area

so the center of government
quite close to Hyde Park.

Up here, we get to the city
of London, the old center,

which is actually
on a slight hill,

so it's actually protected
from flood risk.

In the aftermath of every flood
or near-miss flood,

the walls in Central London,

which protect Central London
from the river,

have been raised.

-As oceans rise,
the Thames is affected

because its estuary flows
into the North Sea,

and that poses further
challenges for London.

-The North Sea
has been described

as the perfect
storm-surge basin.

It's very shallow.

The shallower it is,
the more effect the wind

can have on
raising up sea levels,

but the North Sea
also funnels as well.

-When wind and storms make the
waters of the North Sea rise,

they funnel west
into the Thames Estuary

and up the river to London.

-And that wall of water
has only one place to go,

and we know what's at the end
of this big corridor --

London.

-These storm surges
have flooded London

throughout history.

-1928 in the middle
of the night,

there was high flow
on the Thames

coming into London on the river,
and also,

there was a storm surge
came in from the North Sea.

In fact, the term "storm surge"
was coined

in the aftermath
of what happened

because people didn't have
a word at the time

to describe
what kind of flood this was,

but it actually flooded
the areas of Central London,

of Westminster, in particular,
drowned, I think, 14 people,

caused several thousand
to lose their homes.

-The storm that was London's
wake-up call hit the city

with a massive blow
in January 1953.

-People went to bed that night

with no idea
they were going to flood.

Some people unfortunately
didn't wake up the next day.

-The storm began with high
winds over the North Sea

battering its shores from
Scotland to the Netherlands.

Combining with the rising
spring tide,

a mammoth surge
powered up the Thames.

-The country was different
in those times.

There wasn't any warning system.

There weren't really
any defenses, per se.

-At the mouth of the Thames,

the people of Canvey Island
had no idea what was coming.

Only 11 years old at the time,

Ray Howard remembers being woken
in the middle of the night.

-We were upstairs
tucked in bed when,

all of a sudden, my sister
came into the bedroom and said,

"Quick, there's water
gushing down the street."

-Hundreds of millions
of gallons of water

swept through the town.

-People were clinging
to their roofs

and just hanging on because of
the force of the breach

and the force of the tide
and the heights of the tide.

-The storm tide reached London
around midnight.

As water rose higher
in the Thames,

the BBC issued a warning,

and cars equipped
with loudspeakers

were dispatched
to rouse the sleeping city.

The east end of the city
was flooded

from the Royal Docks
into Canning Town.

At London Bridge,

the water reached
its highest level ever recorded,

threatening to breach
the embankment

and inundate Central London.

-In fact, in center of London,
the river was actually brimful.

It was a major event.

-Then the wind turned
unexpectedly,

and the surge receded.

The center of London was spared,

but still,
the destruction was immense.

-Helicopters, too,
have played their part,

flying in supplies
for the survivors

and helping to maintain
the central services in areas

not yet evacuated.

-Poor people just had
no chance.

59 people lost their lives
on Canvey Island

in that terrible,
terrible evening

but 309 people along
the whole east coast of the UK.

-160,000 acres of land

were inundated across the UK.

The damage was the equivalent
of nearly $2 billion today,

but it could've been
even worse for London,

and the city decided to act.

-That was the foundation as to
why London should be protected.

The flood was quite severe,
and they realized

that if we carry on
in this fashion in the future,

we won't be able
to protect ourselves

from this ongoing problem
of a tidal surge

leading to the riverbanks,

overtopping and actually
flooding the floodplain

all the way down
to Central London.

-The options considered were,
"Do we do nothing?

Do we move London
because the risk is too great?"

Or the third,
"Do you build a barrier?"

-London set about bolstering
its flood defenses

with nearly 200 miles
of embankments,

gates and barriers along the
Thames and its tributaries...

...but it would take $2 billion
and nearly 30 years

to create the crown jewel
of their new system,

the Thames Barrier.

A 600-yard-long floodgate

that runs from New Charlton
to Silvertown

across the Thames
was finished in 1982.

-Tower Bridge,
the last major bridge,

and then the river,
still getting wider,

swings around again
past the old docks going south

and then north again
in a big meander.

This is where Canary Wharf,

big new high-rise
financial center, is.

Further towards the east,

the river is
getting still wider.

We're heading more out to sea,
and then, finally,

we come to the line
of the Thames Barrier itself,

so everywhere to the west
of that is actually protected

by the Thames Barrier

from the storm surges coming in
from the sea.

-Normally, the barrier remains
open so boat traffic

can reach the Port of London,

but when a storm surge
approaches from the North Sea,

10 curved steel gates
rotate up from the riverbed.

This forms a solid wall against
millions of tons of water

that would inundate London.

♪♪

Since its installation,
it's been used 182 times,

and London has not
been flooded once.

Andy Batchelor has been
the manager of this marvel

of flood engineering
for nearly 20 years.

-The barrier is referred
to as the sleeping giant

because if we do our job well,

no one needs to know
because London is protected,

so the tides can come and go,
the barrier close,

and they don't get
their feet wet.

That is the art of good flood
risk management.

-For three decades, the barrier
has kept the city safe

from storm surges.

-The Thames Barrier has been
designed

for a 1-in-a-1,000-year event.

What that means is that there's
a 0.1% chance of London

being flooded as a result
of that barrier.

That is why it works.

-But while it's been doing
its job of keeping London dry,

the climate has been changing,

so now the Thames Barrier
faces a new challenge.

-The barrier was designed
in the '60s.

Climate change, global warming
weren't phrases

in the dictionary then.

-The designers of the barrier
had planned

for higher sea levels,
not because of rising seas

but because southeast England
is literally sinking

at a rate of 1.5 millimeters,

or a 1/16 inch, per year.

-The designers and engineers
who crafted the barrier

made their best estimation
and calculations to factor in

sea level rise in the future,
not thinking of it

in the context of climate change
or adaptation

but recognizing that
the geological formation

underneath the southeast
in London is sinking.

Their appreciation of geology

more than the appreciation
of climate change

is what led them to put,
in effect,

an 8-millimeter factor
of safety every year

into the design
of the Thames Barrier.

If you have a rising sea level
in addition to a landmass

that is sinking,

that's a quite
interesting combination.

-Climate change is now seen
clearly

as a present and future threat.

In London, a dramatic 2013
weather event

exposed vulnerability

in the celebrated
Thames Barrier system.

On December 5, 2013,

Cyclone Xaver smashed
into Britain's east coast,

churning up the North Sea
higher than in decades.

-In the northern parts
of the UK,

the 5th and 6th of December

actually had higher sea levels
than in 1953.

-The storm surge
rushed up the Thames.

The barrier held strong
and did its usual job.

-And that really was the most
significant event

we've had since 1953,
so that was a good test

of the sort of protective
capabilities of the barrier.

-But in that storm,
something new happened.

[ Rain pouring ]

Torrential rain filled
the length of the Thames

with an unprecedented
volume of water.

-The rainfall flow just
didn't stop for 3 months.

-We have storm after storm
tracking across the Atlantic

dumping hundreds of millimeters
of rain on the UK,

so large regions experienced
levels of rainfall

that we've not got
in the observational record.

-The UK had more rain
that winter than in any year

since records began in 1910,

and all that rain...

had to go somewhere.

-The River Thames is big,
one of the UK's biggest rivers.

It's a catchment
that we call it.

Any rain that's falling around
that area

always goes down
into the River Thames.

-By January, England was seeing
a new kind

of flooding called fluvial.

The Thames was flooding,
not draining, the land.

Now the barrier
is put into action

in a way its designers
never intended,

not to keep storm surge
out of the Thames

but to use the river
above the barrier

as a reservoir for excess rain.

At low tide,
the barrier is closed,

leaving the Thames nearly empty
to take on

flooding from heavy rainfall
upstream.

-We've got two factors,
rainfall going one way,

tide going the other,

and what we're able to do
is close the barrier

and stop the surge tide
from going into London.

If we close the Thames Barrier
very shortly after low water,

what we end up
in the center of London

is like an empty reservoir,

so the rainfall is able to come
in and not cause any problems,

and the barrier is shut,

and with all the other defenses
being closed as well,

they're able to contain
that surge tide

and thereby stop
from going into London

and therefore also not overflow,
so we've done a double act

of the reservoirs
contain the rainfall,

and the defenses and the
barriers contain the surge,

so it's that act of looking
after both sides, shall we say.

-Without the barrier's use,
Central London

would've suffered
catastrophic flooding,

♪♪

and there was a limit
to how far the barrier

did work that winter.

In places like Sunbury
on the Thames

just south of Heathrow Airport,

the water had no outlet,
so it overflowed its banks.

[ Indistinct conversation ]

-We watch it coming up,

creeping up the bank
slowly and steadily,

and once it breaks this bank,
you know it's going to --

It goes very fast because once
it's over this brow,

it starts to take
the part very quickly,

and the you know you're going
to be watching it

for quite a few days.

-In a matter of days,
the Kirbys' home is underwater.

Tina, her husband, Adrian,
and daughters

Sujata and Sujaza
decide to stand their ground

as the waters rise
right to their front door.

-Three weeks to a month,
it was here.

It was around the house.
We were --

We would have to wear waders
to leave the house.

-Use a boat.
-Then we started using a boat

to leave the house.

-It's creating a lot of mess
and not going anywhere.

-We would take the children
out in the boat,

you know,
and sail them down the road.

You would try and make fun
where you could.

-Yeah, because if you,
you know, didn't have a laugh,

then you'd probably cry,
but it was better to be at home

than to find yourself
alternative accommodation.

-After nearly a month,

the Kirbys thought
they had won the battle.

-Towards the end of January,

it started to recede,
and so we thought,

"Okay. The worst of it's over,
and things would be better."

It then started to rain again
really heavily.

[ Rain pouring ]

The second time it came,

it came a lot faster.

-Now the water came higher
and higher into the house.

-Probably about --
Was it about that high?

-Yeah, I'd say about
nine inches --

-Nine inches...
-...sort of maximum.

-...that,
so it cleared the skirting

and was into the plaster.

-For more than a month,
the Kirbys lived

with water nine inches deep
in their house.

-And we thought,
"It will be one night.

It'll go away,
and we'll dry it out.

We'll get dryers,
and it'll be fine,"

but, you know,
wearing Wellington boots

in your house,
you put them down,

and they float away the minute
you put them down,

so every time you took your shoe
off to go up the stairs,

you had to make sure
you held onto it.

Otherwise, it would be gone,

and you'd be left
standing there with nothing.

-That is the moment
that you evacuate,

when you get
a cold Wellington boot.

There's no way of drying it.

It's so cold.

That's when you go.

-Across southwest London,

families were flooded
out of their homes.

In total, over 10,000 properties
in the UK

were flooded that winter.

Even in Central London,
which escaped flooding,

the defense systems
were stretched to their limits.

-It was absolutely
unprecedented in that

we actually had 50 closures
of the Thames Barrier.

41 of those were as
a consequence of the rainfall

with the remaining nine
as a consequence of the tides.

Now, to put that into context,
the normal operation

is of the order of about one
to two per year,

so at that time,

we'd only closed
about 160 times in 30 years,

so we saw a third of our
closures roughly in three months

by comparison to 30 years.

-With their prized barrier
working far more

often than it was intended to,

London's future against
the rising Thames

is once again uncertain.

-The flood barriers have made
a difference,

both the permanent ones
and the temporary ones,

but it's clear, in some cases,
they've been overtopped.

They've been overrun, and so,
of course, we should look again

about whether
there's more we can do.

-London has been here
for many centuries.

Currently, we have a population
of eight million.

By 2100, that could
almost double,

and yet everybody wants
to live in the center,

so we're building taller.

We're densifying,
and we're building more subways,

more tube systems,
and we're going down,

so when the rain falls,
where does it go?

So we need space for water.

We need space for it soak
to be able to be stored.

-With heavier and more
frequent rainfall,

there is nowhere
for all the water to go.

What's happening has as much
to do with urbanization

as climate change.

Governments and public utilities
are searching for solutions,

large and small.

-Things like gardens and parks

have been paved over
for a variety of reasons.

There's more runoff,
and it's more likely to cause

flooding than perhaps
a generation ago

when there was just more
greenery around to soak it up.

-15% of Greater London
is considered

to be the floodplain,

most of it in the low-lying
areas alongside the Thames

where approximately
1.5 million people live,

and more are still coming.

About 75% of this
massive urban area

is completely paved over.

With so much of the absorbent
green space

covered with asphalt
and concrete,

the runoff is directed
into sewers and drains,

which can't handle
that excess water.

-It's running off into very old
sewers that were built back

in Victorian times for
a whole different population,

but they're too small, simple.

I feel we have been
put to the test.

I know that this area
is a floodplain, for instance.

They're still building
many flats.

You know, people need
accommodation.

I don't know what they're doing
when it comes to the flood risk.

The Thames Barrier is not
that far away from here.

I have this place
because it's affordable.

The end of the day,
it is in a floodplain,

and I know it's
in a floodplain.

What do you do?

-London needs new solutions
against the increase in rain.

The first challenge is better
prediction of future rainstorms

like those of 2013-2014.

-When '13-'14 came along

and we had such unprecedented
levels of rainfall,

then the immediate question
arises, where did it comes from?

-Professor Adam Scaife
is the head

of long-range prediction
at the Met Office,

the UK's national
weather service.

He says climate scientists
have long known

that global warming will lead
to increased rainfall.

-Something called the
Clausius-Clapeyron Equation,

it's a really
simple equation.

People study it at school,
tells you that,

the warmer the air,
the more moisture it will hold,

and therefore,
when that moisture comes out,

which it must do somewhere,
then you will have heavier,

more frequent downpours

and more mean rainfall,
so that's really clear.

We know that.

The big question is, where?

Where is the rainfall
going to come out?

And that, of course,
is much more difficult.

-Traditional weather-prediction
tools like satellites

provide part of the picture,

but long-term forecasting has to
account for additional factors.

-You better take into account
the increasing CO2

because the temperature is going
to be that much different.

However, if you want to forecast
very long range beyond,

say, a week, the ocean starts
to play a really big role,

and so we have something
called Argo floats.

There are thousands of these
things all over the globe.

It's an international project.

We put them all together,
collect all the data,

and that tells us what the
temperature and salinity

of the ocean is
throughout its depth worldwide.

The ocean is a bit like
a pacemaker for the atmosphere.

The atmosphere is jumping around

with its weather storms
and things,

but the slow guiding force
of the ocean

can steer that chaotic
variability one way or another.

-All of that data is compiled

onto one of the biggest
supercomputers in the country.

-It allows us
to split the globe

into tinier and tinier pixels,

and the more pixels we have
and the more layers

we represent the ocean
and the atmosphere over

and the more accurate
we can get the forecast.

-That allows Scaife
to narrow down

how the rainfall
will affect the specific area.

What the computer's results show
is bad news for London.

-We are very confident that,
in winter,

we're going to see more
rainfall, more heavy rainfall

and more average rainfall
and hence more flooding.

There is, every single winter,

between 5% and 10% chance
of a new record.

Then, after a few decades,

what is now an unprecedent event
will become the norm.

-The Thames Barrier
was designed to be used

just a few times a year.

If it's needed 50 or more times
as it was in the winter of 2013,

it will wear out.

That is a mechanical certainty.

-You know, similar to your car,
if you're always driving

your car,
you're never going to be able

to put it in the garage
to maintain it,

so there's got to be
an optimum figure,

and notionally, just for now,
we've put that as 50,

so we're working towards when we
hit that maximum of 50 per year,

we would need
to have a new barrier.

-And that's without factoring
in the next big problem --

sea-level rise.

London has to plan
for how much sea level

will rise by the end
of the century.

One estimate predicts that
could be from 10 to 35 inches.

-Based on the acceleration
rates we're seeing

at the moment,
we think it's going to be

at least 50 centimeters
if not higher,

but we're expecting
with an acceleration in ice melt

that,
that will gradually increase,

so for London,
the maximum we think it could be

by the end of the century
is about 2 1/2 meters.

That's the physically
plausible upper, upper rate.

-That's 8 feet of
sea-level rise.

The UK Environment Agency,

the government body tasked
with flood protection,

recommended the barrier's
life expectancy

be extended from 2030
until 2070 to buy time.

-Within the original design
criteria for the barrier,

there was enough allowance
to actually mean

that we've got another 40 years

of that high degree
of protection

but ease more life out of it.

-But that was before the winter
floods of 2013

increased the barrier's
workload so much.

More rain and rising seas

will put still more strain
on London's infrastructure.

-You could get such
a severe weather event

that we've never seen
before in this country.

It could overwhelm our defenses.

-Even the best-designed
engineering solutions

can't last forever.

All of London's current defenses

will soon need
upgrading or replacing.

-Whether it's the barrier,
all the walls

in the center of London
or out to the estuary,

you're daft if you don't think
things have a life.

You're daft when you don't plan
for all them coming to an end.

-Increased and more intense
rainfall,

a massive mostly
concrete city surface,

an aging, overused
barrier system

for the mighty but dangerous
Thames River and rising seas

increasing the destructive power
of storm surges.

The UK is bracing itself
for the 21st century

with an array of solutions,

some low-tech, some among
the most advanced in the world.

♪♪

This is the state-of-the-art
Flood Forecasting Centre.

Senior Team Leader Brian Vinall

and his group are armed
with satellites,

radar and coastal gauges

that give them
up-to-the-minute information.

-We have a lot of data,

and we have some very,
very highly trained staff.

They're the ones that have
that decision

as to whether to ring me

and wake me up at 3:00
in the morning to say,

"We need to start
briefing government."

It's up to them to decide
what the response is.

We tell them
what the risk could be.

We try and say how
many properties might flood.

We try and put it into context
about,

"This could be as bad as 1953."

-The prime goal of Vinall
and the Flood Forecasting Centre

is to make sure
evacuation orders

are given early enough
to save lives.

-We're not going to be able
to tell an individual house

whether they're going to flood
in four, five days' time.

What we can do is tell
the emergency responders

that there's probably
going to be a community

affected in this area.

Now, you do get accused
of cry wolf with that.

You do get people who could
potentially by evacuated

and have no flooding happen.

I'd much rather have that
on my conscience.

-Water is hitting London
from all sides.

The problem here
is getting it out.

-An awful lot of flood
risk management

is about moving water around
to places or holding water up

in places where it won't
harm people and property.

Where everywhere
is under the water,

then you start to have
quite limitations

on what you can
do about it.

-The government has
a massive plan

to tackle climate
change this century.

TE2100 is the blueprint
for keeping London

from going underwater.

The Thames Tideway Tunnel
is one of London's

most ambitious
and expensive plans.

It's a massive initiative
designed to channel the water

from overflowing sewers
before it gets to the river.

200 feet below the Thames

and running along
roughly the same path,

it's a £4-billion project that
will take seven years to finish.

-At the turn of the century
here in London,

the Victorian civil engineers

were some of
the earliest pioneers

in providing fresh water
and sanitation

below the heart of our city.

Now, that envisaged a certain
quantum of population,

but that has grown tenfold,
twentyfold.

-Managing the sewage network
for 15 million people

is obviously
a massive challenge.

-Rob Sainsbury and Pascal Lang
are with Thames Water.

The sewer system they oversee,
run end to end,

would stretch halfway around
the world at the equator.

-We're trying to make it
as resilient as possible,

but obviously there are times
when we have extremely

heavy rainfall
where the system can't cope.

-Many of the sewer lines
carry channels

for both sewage and storm water,
which is now a serious problem.

-If we have a combination
of rainwater and sewage,

our sewage reaches capacity,

and then that sewage
then spills out of the manhole.

If people are coming into
contact with that sewage,

that's obviously
a public health concern.

-The current sewer system
was constructed

in the late 19th century.

It was designed principally
to service 4 million people,

and because of the way
sewer systems are built,

it's very difficult to retrofit
them and upgrade them over time.

-A fail-safe is a backup
mechanism

for when a system doesn't work,

and in the case of London's
flooding sewers,

the fail-safe was overflow
into the Thames.

This unsanitary solution
of the Victorian era

still happens today,

and it's a major health problem
London urgently needs to fix.

-So you have sewage going
directly into the Thames.

You have water quality
going down.

At the same time, you have all
the water runoff in order for it

not to flood or it
to be backed up in the system

actually going down
into the River Thames.

So that happens 50 times a year.

-One goal of the Tideway Tunnel

is to upgrade
this antiquated system

and ensure raw sewage no longer
gets into the Thames

by diverting
the contaminated overflow

to upgraded
treatment facilities.

-The Tideway Tunnel is London
now getting its act together

and trying to find a way to deal
with this old sewer system.

It's a tunnel
25 kilometers long,

which lies across the London
Basin of the Thames.

Its function is to allow
for all the water runoff

that comes
from the draining systems,

in addition to the sewage,
to be discharged into the sea.

It's so expensive now to dig
underground in London.

People are put off
because of the price tag.

So in the future, unfortunately
we'll be forced to use it,

whether we like it or not,

whether we like
the price of it or not.

-The Tideway Tunnel

is projected
to be finished in 2023.

Meanwhile, London has
other mega projects

planned for the Thames.

-The T2100 is looking at
improving all the flood

defenses
along the Thames estuary

to improve both the riverbank,

the embankment, the floodwalls
and the seawalls

and the coastal defenses
that are in the estuary itself

to then allow the barrier
to carry on functioning

until 2080 where the idea is

that they will want to build
a second Thames barrier.

-Rather than building a new
barrier now

that's going to cost billions,

they said,
"Let's delay the procedure."

There's some things
that they can do

to extend the lifetime
of the barrier.

They can slightly
overclock the gates.

They can build and use
sort of defense schemes

in and around the barrier.

If sea level rise starts
to accelerate

and gets much higher than that,

then obviously we've got
to go down a different pathway.

Now, the problem with this
approach is

it assumes that you can detect

when sea levels
are accelerating,

and certainly with
the original Thames barrier,

it took 30 years to build,

so there's
a very long lead-in time.

-Considering that lead time,
the Environment Agency needs to

make sure they have a clear
picture of sea level rise.

They've enlisted researchers
like Dr. Ivan Haigh

to make sure they have
the most accurate data.

He observes fluctuations
in sea level rise

that may not be related
to climate change.

Some are part of natural annual
patterns in the North Sea.

-Sea level doesn't just rise
smoothly and gently.

Every year, sea levels rise
as the ocean warms up

in the summer,
falls as the ocean cools down,

so we can see every year
its rising-falling.

-He collects data on other
factors involved

in that fluctuation
like temperature,

salinity, wind
and atmospheric pressure.

He has to work out what
is caused by climate change

and what isn't.

-The way I tend
to picture it is,

imagine you're at a party.

There's 10 people in the room.

Everyone is talking.

Some people are
talking very loud.

So sea level is very noisy.

The acceleration component
is a small, quiet voice.

So what we found is,
when we're able to remove

90% of the noise,
we do now see a very clear

statistically significant
acceleration signal.

Over the 20th century, we saw
about 1.7 millimeters per year.

Now, in the last few decades,
we're starting to see double

that rate --
about 3 millimeters per year.

For the first time
in the UK now,

we are detecting
that the rate is getting faster.

-London's TE2100 plan
is tackling rising seas

and increased rainfall

with multi-billion-dollar
infrastructure projects

and with small-scale solutions.

This project is called
Sustainable Drainage Systems

or SuDS.

Kevin Barton is a landscape
architect working on SuDS,

a localized approach to drainage
becoming popular in London.

-The problem in London,
much like many cities

around the world,
is, over the centuries,

we have paved over large parts
of our landscape.

We've created this impermeable
barrier over our landscape,

which means that when it rains,

what we see is much
larger volumes of water

entering our sewer systems
and eventually into our rivers.

Plus there's none of the slowing
of that water that nature gives.

-The problem when
the rainwater falls

is that sewers reach capacity.

Then they overflow into
basements or onto street level,

and of course with sewerage,
it's foul waste,

so it's contaminated,
which is even worse.

-Jessica Bastock is the flood
risk manager

for Hammersmith and Fulham,
a riverside district in London

that is almost entirely paved
over and prone to flooding.

-So what we're trying
to do here

is to stop that from happening

by relieving the pressure
in the sewer

and actually dealing with water,

the rainwater that falls
on the ground, sustainably.

-SuDS offers a range
of drainage solutions

depending on the site.
-This is Mendora Road,

and along Mendora Road,
what we try to do

is use permeable-block paving
to deal with water.

All that is, is block paving,

but instead of it
being butted together,

it's actually open, so water
can flow between the blocks,

and that means that
when water falls,

it runs through the block paving
and gets stored underneath.

We're on Bridget Joyce Square.

Along this stretch of road now,

there are multiple
SuDS features.

On this side of Bridget
Joyce Square,

we have permeable-block paving.

In between the blocks,
there are little gaps,

and rainwater that falls
on the surface

actually moves
through these gaps

and then into a detention basin.

♪♪

When the basin starts to fill up
during the intense rainfall

event,
there is an overflow point,

so it will go back
into the sewer system,

but it will go
at a really slow rate,

so it will be a trickle.

On this side
of Bridget Joyce Square,

we have a local school.

To incorporate this school
into the design,

what we've done is,
we've taken the rainwater

from the school building,
on the roof,

and we've disconnected
the downpipes,

which would normally have
fed into the sewer system,

and we just channel it across,
and then through little holes,

that actually feeds straight,
directly into the basin.

-Another SuDS scheme
has been implemented

about a mile away
on Goldhawk Road.

-This road,
it's very, very busy,

so in this kind of situation,
what we've had to do

is to have
a sustainable drainage measure

which can fit in this landscape.

Engineered tree pits
were thought

to be the best way forward.

They collect water
from the carriageway,

and then they feed
into the drain here,

and then this is like a lateral
drain, so a flat drain,

and it feeds straight into
the base of the tree pit here,

and then underneath
this tree pit

is lots of box-crate storage,
which holds water.

-Kevin Barton believes SuDS

will be commonplace
across London by 2100,

incremental steps
with a big result.

-Feels like we're on a steep
curve at the moment

where more and more people
are coupling onto SuDS.

When you understand
it saves money,

it's good for developers
as well as the environment

and as well as flooding.

From everyone's perspective,
SuDS is a no-brainer.

-SuDS are good,
but they're a soft solution.

The difficulties in Thames
is that,

if you have
a flash flood incident,

and it rains, and there's
a large amount of rain

in a short period of time,

that in itself becomes
an impervious surface.

SuDS aren't able to deal
with that type of water runoff

whereas a sewer system can,
specifically the Tideway Tunnel.

-As London looks to the future,

it also looks to the past
for overlooked options.

-By the mid-19th century,
most of the tributary rivers

would become effectively
open sewers,

and they were heavily polluted,

and they were faced with
a public health crisis.

Their response was to bury
those rivers,

pipe them up
and build over the top of them.

It also created more space

because they could be built
on top of,

so it made way for development.

-The project,
run by David Harding,

revolves around a network
of lost rivers

that lie beneath London.

-London lost about 26 of
its major tributaries,

rivers like the Fleet
and the Tyburn and the Walbrook.

There were lots of cases
where we were investigating

flooding in the urban area

where we couldn't really account
for where all the flow came from

because those rivers
still do function

as rivers when it rains.

-And that's at the heart
of many of today's

flooding problems in London

and other global cities
built over rivers.

-So what we've got to do now
is to start to restore

some of the more natural
drainage of London.

Rather than wait for these
water courses

to reveal themselves
when they flooded,

go out and look for them
proactively to understand

where all the rivers
have disappeared to.

We start off from the LIDAR
mapping,

the digital terrain mapping,
to look for telltale signs.

The blue is the highest ground
going down to the yellow,

which is the lowest ground,

and you start to see
what looks like a floodplain

or a river valley with networks
of tributaries coming off of it.

We then start to refer
to the historical mapping.

So taking one of those potential

flow pathways
from the LIDAR data

and referencing it
to a map from 1846,

you can start to see that the
Salmons Brook is actually mapped

when it coincides very well
with the LIDAR data,

and at this stage
in the urbanization,

the river was still
on the surface.

-Guided by high-tech data,

he takes the search
from the office to the field.

Harding is in a suburb of London
where he hopes to find traces

of the city's
Victorian shape and structure.

-So we're on Nestor Avenue
now where we believe

that the Houndsden Gutter,

a lost watercourse,
flows to my left.

If you put a river in a pipe
or a channel,

it's got a finite capacity,

and when that capacity
is reached,

then that's when you start
to get flooding

coming out of things
like manholes,

flooding into properties
and gardens and roads

as opposed
to the natural watercourses,

which could flood out
on the floodplains,

which, in many cases,
are still there.

So if we could daylight some of
these watercourses in the areas

where they can be allowed
to safely flood,

then that reduces the flood risk
to the built-up area.

-Daylighting means opening
the river back up

to its natural state,

giving the water
more room to flow,

but since they've long been
covered over,

these rivers have disappeared
from modern maps.

-Okay, so the map has led us
to the open section

of the watercourse
that's to my left,

and there should be a pipe
or a tunnel linking that

to the next visible
open section of watercourse,

so we're just going to go down
into the river now

and walk the river and look
for the existence of the tunnel.

♪♪

-Harding discovers that his
software correctly identified

the existence
of a buried section of river.

-This conduit that was built
when the road was built,

when the houses were built,

this was just a way of
putting it in a nice,

straight line
that was out of people's way,

and it's typical of thousands
of kilometers of ordinary

watercourses across London.

-Most of the people who live
and work in these shops

and cafes have no idea a river
once ran through their community

and may soon be flowing again.

-There's no reason
why they couldn't be restored

to a more
natural river corridor.

Now that we know it's here,

we can understand any upstream
flood risk that's caused

by the throttling effect
of this tunnel,

and we can then look for
opportunities to allow the river

to spread out
into safe open areas.

-So far, over 11 miles
of lost rivers in London

have been daylighted.

♪♪

One of the best examples
uses landscaping with earth

bunds or embankments here

at the Firs Farms Wetlands
in Enfield in north London.

♪♪

♪♪

-We identified that using Firs
Farm as a flood storage area,

we could protect quite
a significant number

of people living downstream.

We realized that instead
of building a concrete wall,

we could build a natural earth
bund as a defense

and to generate the spoil that
we needed to build that bund,

we could carve out a channel,

and that channel has now
become the restored river.

-Though the wetland is about 12
miles from the center of London,

the project is already
having an impact,

reducing the amount of rainwater
flowing into the Thames' system.

-And we realized that using
wetland planting,

we could mitigate
the urban pollution.

You can actually clean
that water by passing it

through a filter bed system.

We've ended up with
a combined wetland

and flood storage area here,

and by combining
those two things,

you get multiple benefits.

You've got the permanent
habitat, which is always here --

the wetlands and the plants
and the wildlife and so on.

You've got an area that local
residents can come and visit

and enjoy on a day-to-day basis,

but you've also got
a functional landscape

which actually stores tens
of thousands of cubic meters

of water during intense rainfall

and protects people
living downstream.

-Harding sees this kind of
organic approach

to flood prevention
as a necessary complement

to large infrastructure
like the Barrier.

-The scale of hard engineering
that's needed

to start to address flood risk
through climate change now

is becoming unfeasible,
you know?

We can't go for the big-tunnel
solutions forever,

so we need to start
sort of rolling back

some of the urbanization
and sort of managing flood risk

in a more natural way
like this project does.

♪♪

-Another more radical solution
is not to battle the rising sea

but to work with it.

Richard Coutts is an architect
and urbanist

specializing
in floating architecture.

-London is particularly under
threat through climate change.

We have sea level rise,
and we're seeing more rainfall.

We are building more,
and the upshot of that is

there's just not enough capacity
in the system

for this rainfall to go.

To meet those challenges,
we need to use the water space.

We need to inhabit.

We need to optimize
our resources.

Casting our minds forward to
the next 50, next hundred years,

one could imagine London
thriving at the water's edge,

new communities just growing,
inhabiting the water space,

the parks, new homes, businesses
right in the heart of cities.

-And Richard's secret weapon?

-And we're looking at
floating communities.

We've actually coined the phrase
"aquatecture,"

which is essentially
architecture on water.

So we're currently located
in the Royal Docks of London.

We are in a floating hotel.

This was constructed in the turn
of the 19th century.

The Good Hotel is unique
in terms of its thinking.

It's a traditional industrial
unit on a floating base.

This was formerly
a prison building

that was birthed in Amsterdam.

It was no longer fit
for purpose,

and this is
one of the wonderful things

with floating architecture --
it has flexibility.

You take it somewhere else.

You give it a fresh lease
of life,

and from a building
which previously people

were fighting not to get in,
we're now in a situation

where people are paying
a premium to dwell,

to rest right
on the water's edge.

-Aquatecture is design
that combines with water

rather than resisting it.

It's something Coutts believes

is a solution
in London's future.

-And we're looking at
the existing communities

and how to make
those resilient.

We're looking at stilted houses
and amphibious dwellings,

and then at the other end
of the scale,

we're looking at floating
and flood-resilient communities.

This is the UK's first
amphibious house,

and it's built 8 meters
from the River Thames

and is a house which is designed
to rise and fall with the water.

This is more of a practical
approach,

which allows the people who live
here to be within their garden

and to be low,

but in the event of a flood,
the house is more responsive.

The benefits of
an amphibious house are,

in the event of a flood,
the house can float.

It can literally move up
and down.

The garden is designed
as an early-warning system,

and what we've got is
a series of tiered plains

almost like buckets.

When the first two fill,

it actually triggers
the buoyancy of the house.

-Architecture that works with
rather than against the water

is an idea being considered

by designers
and engineers worldwide.

Coutts believes that floating
structures will be embraced

by the world's
most powerful players.

-Floating cities, those cities
which really grow,

those which are at the forefront
will be those that utilize water

in that adaptable fashion
to bring in a floating Olympics,

to bring in those
floating expos,

to providing housing, to meet
the needs of their workforce

in the middle of the city,

and water provides
that opportunity.

-For decades, London trusted
the Thames Barrier

would keep it safe from water.

Now, that sleeping giant
can no longer be relied upon

as rainfall increases
and sea levels rise.

-You know,
the risk to London is huge --

1.25 million people, £375
billion worth of infrastructure.

You know, there is 400,000
properties.

You can just keep on going
with the stats.

We can't fail.

We've got to get this right.

-Still, the people of London
aren't feeling

as safe as they once did.

-I think, if it rains for more
than three days in a row,

I start thinking,

"Is this going to be another
one of those winters

where we start getting rain
after rain after rain?"

-The city's search for
multiple solutions continues.

-I think that sort of
the approach

that the Victorians took,

that, you know, you could always
throw enough technology

and enough concrete
at a problem,

and you could overcome it,

but, you know,
there's an acceptance

that that's not appropriate
in all circumstances,

and a more natural approach
to flood risk management

is the only one
that's going to be sustainable

in the face
of more severe weather,

rising sea levels, you know,
more prolonged wet periods.

-We need clever architects,

designers that can build cities
that can cope with sea levels

and almost make that part of
the future design of the city.

-The challenges are immense,
as are the stakes,

but London
is ready for the battle.

-In London, we need
to make a few decisions.

You can see we have
some wonderful heritage,

and we need to protect
and defend that,

so maybe in these areas,
we maintain our flood defenses,

but in other areas of the city,

we need the capacity in the
system for this volume of water,

and we may have
to consider retreating,

taking down
some of those buildings,

creating parks to provide
additional storage.

We can still use those
as recreation,

but we need to think
more intelligently.

We need our policy makers
to keep up,

to be with us on this journey

as we deliver this
very innovative infrastructure

and new ways of living
to enable our cities to grow.

-So right now,
the biggest challenge

is to let planners,
policy makers,

the people who
make decisions understand

that we have to actually
streamline these systems

so they can function as one,
and I think that alone

is a big challenge
of what London needs to do

to move into the 21st century
in its foremost.

So adaptation challenges
our current way of thinking.

It challenges everything
we think we do and say

and based not in the name
of sustainability

but in the name of resilience.

-Well, even for wealthy cities,
this is going to be a challenge.

They're going to have to watch
this very carefully.

It's going to require

a significant amount
of investment.

That investment will be
an increasing proportion

of the economic activity
in that city,

and this is going to be
the issue for the 21st century

around a number
of coastal cities.

♪♪

Narrator:
Next time, Miami is considered
the most at-risk city worldwide

due to rising sea level
and storm-related flooding.

We're gonna get probably 2 feet
of sea-level rise by 2060.

Then, by 2100,
we might get 6 feet of water.

The water is coming.

We already see 20 days a year

that, just high tide, the water
is higher than the land.

Man: Water is coming from the
side, from below, from above.

Miami is at that point
where they've got to decide,

"How do we solve the issues
of sea-level rise?"

♪♪

-To order
"Sinking Cities" on DVD,

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

This program is also available
on Amazon Prime Video.

♪♪