All language subtitles for D D S02E05 Floods 1080p AMZN WEB-DL DD2 0 H 264-playWEB_track3_[eng]

We live on a water planet,

with 71% of the Earth’s surface
covered in water.

Only 2.5% of the Earth’s water
is fresh water...

held in the ice caps,

lakes...

rivers...

clouds and streams.

We need water for life,

to drink and irrigate crops.

Not enough water,

and the land withers
under drought.

However, too much water
can be just as deadly.

When normally dry land
overflows with water,

you get flooding...

a natural occurrence,

sometimes benign
and sometimes catastrophic.

When we have very,
very big flood events,

there’s not a lot you can do
to get out of the way.

Floods exist in the present
and are part of our history,

featuring in the legends we use
to make sense of the world.

Floods are among the most
costly natural disasters,

affecting the largest
populations of people

with far-ranging consequences,

including damage to property,

disease and loss of life.

In this Deadly Disasters,

we will look at
the different types of flooding

and investigate the reasons
why they occur.

Our experts will look at some

of the most
catastrophic floods

of recent years.

We will consider

how different countries
manage flooding,

particularly in the developing world,

where resources
can be stretched thin.

Eyewitness reports will tell
the human story of flooding

and the personal toll
these events take.

Flood-prone areas

can also tend
to be highly populated.

Low-lying flood plains adjacent
to rivers attract people.

The flat land is easier
to build on.

Proximity to the river is good
for farming and irrigation.

Rivers allow for people

and supplies
to be transported,

and previous floods provide
nutrients that farmers need.

The human impact of floods
can be catastrophic

when they hit in areas
of dense population.

By the time people
got back to their homes,

there were no homes anymore.

Floods kill
more people each year

than any other form
of extreme weather.

The cost of flood damage
is astronomical,

up to 40 billion U.S. dollars
per year in the U.S. alone.

Water is part of the landscape,

collecting in ponds and lakes
on the surface

and as aquifers
and groundwater below.

Rivers and streams
collect water

and move it downhill,
eventually back to the sea.

In normal circumstances,
the geography of most locations

prevents extreme floods
from occurring.

Water drains into the soil,

runs into the rivers

and is carried away
eventually to the sea.

Water is also intercepted
by plants,

and some of it evaporates.

The landscape is efficient
at moving it from the surface

via streams and rivers
to the sea

or allows it to slowly soak
into groundwater.

Floods happen when water
is added to a landscape

quicker than it can be
carried away...

when the surface becomes
waterlogged

and the flow of water exceeds
what can be carried away.

Floods occur when water remains
in areas not used to water.

This excess water can
come from precipitation,

coastal storm surges

and meltwater and runoff
from higher ground.

Flooding can be small
and localized,

presenting minimal danger
to local populations.

In extreme circumstances,

floods can cover huge areas,

many thousands
of square kilometers

for weeks at a time,

causing life-changing consequences

for the people affected.

Even six inches of water,
or 15 centimeters,

is enough to knock a person
off their feet.

And even 30 centimeters,

or a foot,
of water can move cars.

And so when you have
a flood event

that can be several meters deep,

that can actually
force people to the roofs

and need immediate evacuation.

Coastal areas present
a particular flood risk.

Large areas of low-lying land
risk sea flooding

from storm surges
and precipitation.

Areas close to the sea

often receive more rainfall
than inland.

In the U.S., this can be due

to atmospheric rivers.

Conventional land rivers
are a place

where water accumulates

and flows
in the same direction,

taking advantage
of the geography

to concentrate flow
in troughs and gullies

to carry water quickly
across the land.

Atmospheric rivers
that form in the sky

do the same thing
but with water vapor.

Long, thin areas
with high moisture content

transport water thousands of
kilometers across the globe.

Often fed by water evaporation
in warm Pacific waters,

atmospheric rivers
are responsible

for much of the rainfall
in North America.

Carried on fast winds,

the water vapor remains
locked in the atmosphere

like a saturated sponge

until something comes along
to squeeze it out.

That can be the edge
of a continent

forcing water out of the air

and triggering
torrential rainfall.

Much of the precipitation
in the U.S.A.

is transported
by atmospheric rivers.

Coastal areas often bear
the brunt of storms.

Large waves can develop
over large distances

and then release
all this built-up energy

onto the land as a storm surge.

A storm surge is when you have
a raise in the ocean level

because of low pressure
in the atmosphere.

And that’s compounded with wind
that’s blowing the water

from the sea onto the land.

So you get
this kind of surge in water,

which means you can
get floods further inland

than you would
with just a high tide.

Extreme storm surges

can overcome flood defenses
and drive water inland.

In the United States,

one of the biggest surges

was caused by Hurricane
Katrina in August of 2005...

resulting in water levels

of eight meters
above high tide.

Hurricanes pick up a lot
of energy and water moisture

from traveling over the ocean
and warm waters,

and when they reach landfall,

they can dump a lot
of that water onto the land.

When hurricanes make landfall,

bad things usually follow.

The levels
of devastation that you see

in these types of events
is huge, it’s massive,

and what we see on the TV

when we see pictures of people
standing on roofs,

that is just
the tip of the iceberg.

Hurricane Harvey was the
second most costly hurricane

to hit the U.S. since 1900.

It began as a tropical storm
in the Gulf of Mexico

around August 17th, 2017.

When extreme tropical cyclones
occur,

like Hurricane Harvey,
the amount of rain

that falls from them
will be even greater.

It had become
a Category 1 hurricane

by the 24th.

By the next day,
it was upgraded to Category 4

and en route to Texas.

When Hurricane Harvey tracked
over the Gulf of Mexico,

the Gulf of Mexico was actually
much warmer than normal.

And so that gave the hurricane
itself a lot more energy

and was able to pick up
a lot of water.

And so when it made landfall,

it dumped
all that water on land.

As the flood bore down
on the coast,

flood preparations began.

Aware of the storm and
potential floods to follow,

the citizens of Houston
prepared.

Forty-one thousand
emergency shelter beds

were made available

and 200 buses put on standby

to move people inland
from the worst-hit areas.

In the buildup to the landfall,

the Houston mayor,
Sylvester Turner, tweeted:

If you choose not to evacuate,

it means that somebody’s going
to have to come and rescue you.

The evac horn went off, and
they said you have five minutes

to get whatever you can
and let’s go.

So we had to climb over
the back wall,

we had to walk
from the back of that wall

on the back of our house
in thigh-high water.

The next morning,
it kind of hit me,

I’m like, "Oh, my goodness.
I don’t even know

if I have a house or a car,
I don’t know."

And I cried for a minute,
and then I prayed about it.

There was another lady crying,
I went and gave her a hug.

On August the 25th, it makes
landfall on San Jose Island

in southern Texas,

with 210-kilometers-per-hour
winds

and a massive storm surge.

The next day, the winds calmed

and the event was downgraded
to a tropical storm.

Yet, whilst the winds
may have abated,

the rain did not let up.

By August the 27th,

Harvey had dropped
a year’s worth of rain

on Houston in just five days.

That amount of water
falling over a city

or a very built-up area
is absolutely devastating.

It’s relentless,
and the drainage--

Both the natural and the
engineered drainage capacity

just can no longer cope
with that amount of rain.

The rainfall was described
by many commentators

as an historic amount of
rainfall, a 500-year storm.

Harvey was particularly intense

because when it reached
landfall, it stalled

and moved very slowly
along the coast.

And it was bringing water
from the Gulf of Mexico

and dumping it over Houston.

And essentially the storm
moved on and off the land

around five times
before it dissipated

and moved northwards.

The ability to predict flooding

has a huge impact
on how the response is managed.

With enough time,
people can be safely evacuated,

emergency services primed
and flood defenses shored up.

So there are two main ways

that you can really limit
devastation from a flood.

The first one is to be prepared

and to know what to do
when a flood is coming.

And the second one is to know
where to get warnings from

so that you can hear
what the latest information is.

Put simply,
sufficient early flood warnings

can actively save the lives
of people in high-risk areas.

Early-warning systems
are an important tool

to tackle floods.

Flood predicting requires
real-time, on-the-ground data,

from rainfall
to ground moisture

and knowledge
of the landscape.

Flood forecast tools
have been developed

to apply rainfall predictions

onto three-dimensional maps
of the ground.

By looking at the topography
and the ground cover,

water flows can be predicted

and floods can be mapped
at street level,

sometimes up to 48 hours
in advance.

The University of Loughborough
have trialed

this type of flood map system
successfully

in four U.K. cities,

with hopes to make
an international product soon.

Satellite imaging has been
an important component

of weather prediction
for some time.

Storms can be tracked
and monitored

as they move across the globe,

making it possible to predict
when they make landfall.

This satellite data is key
in predicting floods,

since being able
to estimate the times

and amount of rainfall
in an area is key.

NASA scientists have developed
satellite capability

even further.

By measuring microwave
emissions from the landscape,

it is possible to assess
soil moisture.

The Soil Moisture
Active Passive system

is able to measure the soil
moisture for the entire Earth

in just three days.

Soil moisture is an important
data set for flood prediction

because it allows researchers
to know

how much rainwater
can soak into the land.

A large data set like this,

combined with
weather predictions,

increases the ability to make
global flood predictions

on a large scale.

If an area is already
deemed waterlogged,

then they will be
able to know

if the coming rain
will bring with it

the risk of flooding.

In Houston,
more water was being dumped

than the drainage systems

and natural runoff
could cope with.

It had nowhere to go.

It’s never been
like this before.

I mean, it’s awful,

but, you know,
we’re getting everybody out.

Police and the fire department
were here yesterday,

helped us get more out,
so we’ve been okay.

With Harvey, people were not
really expecting this to happen.

So they weren’t prepared.

So they didn’t take the actions
they could have taken

to protect themselves
and their property.

Urban areas exacerbate flooding
for several reasons.

Flood risk is reduced
by vegetation.

Plants intercept and absorb
some of the water,

slowing its propagation
downhill.

The water is given time
to soak into the soil

rather than gather
on the surface as a flood.

Urban development reduces
the vegetation,

replacing it with concrete,
buildings and tarmac.

Modern building materials
coat the land

in an impermeable layer,

preventing water from soaking
into the ground.

Instead it collects together
and starts to pool.

Drainage can only do so much,

and few cities have systems
in place

to remove hurricane-levels
of water quickly enough.

Good flood infrastructure
can prevent cities

from the risk of flooding.

However, even the most
sophisticated technology

comes with problems.

We have something called
the levee effect.

It’s very common to find people

who live behind
very large flood defenses

are actually much less prepared
for a flood when it happens

because they’re
perceived to have
a very high protection level.

But when their protection level
is breached,

they’re not prepared.

So you need to know

how high the water
is going to get.

You need to listen
to those warnings

about what’s going to happen.

You can move things upstairs
if that’s a possibility.

You can switch off
all electricity.

That’s very, very important
to stop fires.

And you can evacuate.

If you really need to,
you should go.

Houston was battered
by up to 50 inches of rain

in just a few days.

The flooding happened quickly.

We know
that there was a problem

with the communications
with the Texas floods.

We know that there were
some very good warnings

issued 30 hours ahead,

saying there was devastating
amounts of rainfall coming,

but some people didn’t seem
to receive those warnings

or really know what to do when
they received those warnings.

Five people were killed
in the initial storm.

If you see the news,
everybody’s helping each other.

They forgot about race,

they forgot
about what color you are.

More than 135,000 homes were
affected by the flooding.

Floods cause
terrible devastation

to buildings and property.

The structure of buildings
can be damaged.

Furnishings, carpet
and plasterboard

become soaked
and waterlogged.

A lot of this material has
to be ripped out and scrapped

when the waters recede.

Cars and electricals
are destroyed.

In addition to homes,

industrial areas are
also affected.

Houston is a big player

in the petrochemicals industry,

and toxic chemicals leached
into the floodwater.

Elevated levels of chromium,
nickel and arsenic

were found in the water,

which are detrimental
to people,

animals and sea life.

The effects of floods on people

is just as dramatic.

With fast flows
and storm surges,

people risk
being washed away,

injured and drowned.

But even slower-rising floods

can present a large risk
to human health.

It’s not only the damage
that the water actually causes

to buildings and properties,

but it’s also the contaminants
it can bring

that even after a flood
can cause many diseases.

So cholera, for example.

You having--?

I think he’s having a seizure.

I’ll check on him.

One of the most common
misconceptions about flooding

is that nice clean water will
be running through your house.

And what’s left behind actually
is huge amounts of silt,

disgusting debris,
you know, sometimes sewage,

and it can really, really last
a long time,

that problem,
trying to clear that up.

As people fled the floods,

shelters soon became
overburdened

and firefighters began
a door-to-door search

to look
for trapped survivors.

Elderly and disabled people

who are unable to escape
the initial floods

can end up
trapped in their own homes.

The rescue efforts took nearly
two weeks to complete.

During that time,
trapped people risked illness

due to exposure,
lack of supplies and disease

spread by flooded sewers.

floodwaters hamper
rescue efforts.

The high water levels and
sometimes fast-flowing water

mean that often boats
and helicopters

are the only way
people can be reached.

Everybody around here’s stuck
in the house

unless they already left
ahead of time, so...

But I came two times,
I talked to them over and over,

and they finally came around
there and just...

When you get
a big city flooding,

it can be very frightening
for the people who live there.

Their entire lives
are caught up in that city.

There is really nowhere else
for them to go.

And they lose electricity,
they lose their ability

to walk across the city.
They don’t know what to do.

Floods can leave
people desperate.

Where do you all live?

It’s really a low-type person
that would come in and--

When you this, how devastating
it is to your heart,

and knowing people are
suffering without insurance,

it’s devastating that someone
would wade through water,

through snakes and alligators,

to come and take
people’s possessions.

We’re our own police force
right now.

So-- And I think
all over Houston

people are kind of taking
the same stance.

You’ve got an AR-15 here,

we’ve got a .357 semi-auto

and then two 9 millimeter
with 5.56 NATO rounds,

so a full metal jacket,
you know.

Floodwaters take time
to recede,

delaying people’s return home
to pick up the sodden pieces.

Homes and furnishings
are waterlogged,

and damp and mold has set in,

meaning many of the house’s
contents need to be dumped.

Once a flood has just happened,

people view their homes
very differently.

This is the place
they felt most safe.

And now it’s just been
devastated by flood.

So it’s very difficult for them
to come back to that

and feel safe again.

People have to start again.

Rebuilding can take years.

People expect governments to
protect them from all floods,

and this is quite problematic

because that’s
completely impossible.

We don’t know
when the next major flood

is going to happen in Texas

and if it will be on
a similar scale to Harvey.

Hopefully lessons
have been learned from 2017

and can be applied
to help save lives

next time the flood comes.

Storm surges are inevitable,

and it’s impractical
to fully mitigate the risk

with flood defenses.

World coastlines are
much too long

to physically protect
with barriers and levees.

The quantity and intensity
of storm surges

are influenced by the tides
and level of the sea.

Most of the earth’s fresh water
is stored as ice

in the Arctic and Antarctic
ice shelves.

The Antarctic ice sheet alone

covers an area of almost
14 million square kilometers

and contains 30 million
cubic kilometers of ice.

During the summer,
the ice recedes,

adding meltwater to the ocean.

In recent years,
the quantity of ice

melted at the poles
has increased.

The change
to the world’s climate

has resulted
in a warmer planet,

and if temperatures
continue to rise,

more meltwater could be added
to the sea.

Sea levels have been rising

one to two millimeters a year.

If more drastic melting occurs,

for instance,
if the West Antarctic Ice Sheet

were to melt
or move into the ocean,

global sea level would rise

approximately eight meters...

automatically flooding
many low-lying areas

and increasing
the storm-surge risk.

A sea-level rise of this scale

cannot be practically
defended against

with traditional
flood defenses.

Preventing the ice from melt
occurring in the first place

is our best hope to avoid

a dramatically
reshaped landscape.

For instance,
much of Florida

could be underwater

in a worst-case scenario.

Flooding due to ice melt

doesn’t just occur because of
rising sea levels.

It can happen inland as well.

Mountainous areas can contain
large stores of water

in the form of snow caps
and glaciers.

In Europe, actually 30% of
floods are driven by snowmelt.

The snowmelt floods are
actually occurring more often

and occurring
earlier in the year.

Glaciers are
literal rivers of ice,

containing many thousands
of tons of water.

Central Asia’s glaciers contain

the third largest mass
of fresh water in the world.

Springtime brings
warmer temperatures

and flash thaws.

The meltwater can be sufficient

to cause dramatic flooding
at lower altitudes.

As glaciers melt,

lakes can often form
in glaciers.

This erodes the land

and creates a depression
that fills with meltwater.

It can burst at any moment
if they are not drained.

And then the threat
for the community will be

that suddenly, hundreds
of thousands of cubic meters

will come downstream and
will wash anyway everything.

And when I say wash away,

it’s really,
wash away their houses,

their livelihoods and of course
the people themselves

and their animals.

A glacial lake outburst occurs

when a dam made of ice
or terminal moraine,

holding back a glacial lake,
fails,

causing flash flooding

and the release of rocks
and other debris.

Ice can also cause floods
when it melts too slowly.

The Huang He,
or Yellow River,

is China’s second
longest river.

It is also a river that is
prone to frequent flooding.

Parts of the river can freeze

and then thaw
at different times.

Ice can form and block
parts of the river,

causing a wall of water
to develop behind it

which can then
eventually spill out

and cause mass flooding.

Rivers such as these can become
a never-ending hazard

and have the capability

to unleash
huge quantities of water

both in winter and spring.

Ice can cause floods

and, surprisingly,
fire can too.

Uncontrollable wildfires
are a deadly disaster

perhaps not usually
associated with flooding...

particularly as they are
opposite in their requirements.

Floods require moisture,

and fires, the absence of water
and drought conditions.

Surprisingly, wildfires can
increase flood risk.

Rainwater that falls
on hills and mountains

can cause floods downhill
if the water flows unabated.

The faster water flows
downhill,

the more likely
a flood is to occur.

The water supply needs
to be fast enough

to overwhelm
a location’s ability

to remove the excess water.

Vegetation such as forests
reduces the flood risk

because trees intercept
some of the water

and the root systems slow
the water down,

giving it more time
to soak into the soil

rather than flow downhill

and contribute
to any lowland flooding.

Fires clear the tree cover,

resulting in nothing
to slow down

and intercept the water.

It runs down hill uninhibited,

free to contribute
to any flooding.

The charred ground
is less permeable,

preventing the water
from soaking in.

It has nowhere to go
but downhill,

potentially picking up
fine ash from the fire

and creating
dangerous mudslides

as well as dumping water
quickly

on the now flooded lowlands.

Burn scars increase
the flood risk

in ways that are similar
to covering large areas of land

with concrete.

It concentrates the flow
in a similar way.

In some cases,

less than half an inch of rain

is enough to trigger
flash flooding.

The most damaging floods
are flash floods.

So these happen when we have

a very sudden, heavy amount
of rainfall

falling over the land.

And when this happens
in urban areas,

it can take everybody
by surprise.

And so these
are very intense events

that people aren’t
prepared for.

We find it very difficult
to predict these events.

And so these can be actually
the most dangerous.

After a wildfire,
eventually the land recovers

and the vegetation starts
to grow back.

The flood risk diminishes

in proportion to the density
of ground cover.

Each burn scar poses
a unique risk of flooding

due to a variety of factors
that need to be considered:

The proximity
to human settlements,

burn severity,

steepness and size
of the burned area.

This, however,
does take time,

and upland burn scars
in many places

are considered a flood risk

for at least two years
after the fire.

In December 2017,

the Thomas Fire burned
708 square kilometers

of Southern California.

It was the largest wildfire
in California’s history.

November is normally

the rainy season
for California,

but that year the rains
didn’t come until January,

allowing the fire to burn
for over a month.

It took until
January the 12th, 2018,

before the fire was brought
under control.

The rains helped
put the fire out,

but they also triggered
flash flooding

made worse
by the extensive burn scars

produced by the flames.

Heavy rain that had fallen
on burn-scar areas

from the devastating
Thomas Fire

triggered waves of flowing mud,
rock and debris.

On January the 9th, 2018,

the Southern California town
of Montecito

became overwhelmed
with destructive mudslides

which came crashing down
onto homes and roadways.

Hundreds of homes
were damaged or destroyed.

Two thousand and seventeen,

the same year
that Hurricane Harvey

dumped trillions of gallons
of water on the U.S. coast,

countries in South Asia
also suffered

from a catastrophic
monsoon season.

Flood can affect
just an individual house

or an individual area,

but it can also affect entire
communities and entire cities.

In fact,
the most damaging floods

can even affect multiple
countries at a time.

The main areas affected
included India,

Bangladesh and Nepal.

These are
lower-income countries

with large populations
of people

in the potential flood zone.

When there’s so much water

and a country can’t deal
with that by rescuing people,

getting people out the way,

communities are left
to fend for themselves.

And that can really make
these disasters deadly.

Bangladesh in particular
is prone to flooding.

It’s situated on
the Brahmaputra River Delta.

Eighty percent of the country

is considered
part of a floodplain,

with a large proportion
of the country

never rising more than
five meters above sea level.

Because it’s so flat,

when Bangladesh floods,

the water has nowhere
to run off.

This results
in long-lasting floods

that submerge the land
for weeks at a time.

Floods in Bangladesh
are fed by rainfall,

water flashing
off the hills above

and storm surge
from its coast.

Every year, it deals
with this triple flood threat

causing floods that cover
up to 18% of the country

most monsoon seasons.

The monsoons are very tricky

because every year
from June to September

these regions rely on
this monsoonal rain

for crops
and for their agriculture.

But when you have
a very intense monsoon season,

this can then lead
to devastating floods.

In addition
to being low-lying,

Bangladesh is
a densely populated country

with 165 million people.

In many areas,

regular small-scale floods

are a blessing to farmers.

They irrigate and provide
nutrients for crops.

However, this, in turn,

attracts more people
to these flood-prone areas

because of the rich farmland.

Unfortunately,
when large-scale floods hit,

there are more people
living in the affected areas.

Building flood defenses

represent a considerable
engineering challenge.

Water is heavy,

and in quantity,
floodwaters impose

considerable pressure
on any flood defense.

They need to be built
to withstand the pressure.

The building of these defenses
are resource-heavy

in terms of materials,
labor and cost.

Countries with a smaller
gross domestic product

have less money to invest
in adequate flood defenses.

This can result
in a greater flood impact

than would have
potentially occurred

in the better-funded nations.

However, flood preparation
takes many forms.

And even with
its limited resources,

Bangladesh is used to flooding

and in 2017 was considered
by many

to be better prepared
for flooding than India.

The economic impacts
of floods are huge.

They not only affect individual
people and their households

but they affect
the whole government,

the whole way
of doing business.

We can have
business loss occurring

for months after a big flood,

and that
doesn’t even take into account

the economic cleanup.

Bangladesh’s experience
of regular flooding

resulted in more investment
in flood management.

For instance,
public schools and mosques

were built with the ability

to also serve as shelters
during flooding.

In previous floods,
food supplies ran out,

partially due
to the disruption to farming

but also because the floods
prevented the easy distribution

of emergency food
to affected areas.

To prevent this from occurring,

in 2010,
Bangladesh instigated a policy

of maintaining a food surplus.

Now grain is stockpiled for use
in the event of disaster.

The severe floods in South Asia
in August

happened in
the three connected countries

of Nepal, India and Bangladesh
at the same time.

Their river systems
are interconnected

across the vast geographical
Ganges-Brahmaputra basin.

These are very, very
large rivers indeed,

and they have a lot of
power associated with them,

so when you get
that amount of rainfall,

with these huge rivers

and you have people living
in the way,

perhaps not
with very strong homes,

nor the ability
to move themselves

and their livelihoods
out of the way,

then you will
get people dying.

Floods, however,

don’t respect
international boundaries.

They are
a transnational affair.

Cooperation between countries
is needed

to ensure floods
on this level can be dealt with

and those affected
can be reached.

If you see
the extent of the flood,

it can happen
for miles and miles.

And people living
in very rural areas

can be cut off
from the major centers.

And so, literally,
you have no communication

and no means to communicate
with people back,

and the authorities
in the city,

so are just dependent
on the aid agencies

and first responders
to find them.

In India,

streets in Mumbai turned
into rivers

and people waded through
waist-high waters.

Rainwater swamped

the King Edward
Memorial Hospital

in central Mumbai,
and doctors feared

the rainwater would
spread infection

as the water mixed with rubbish
and detritus.

In Nepal,
the floods spanned across

and impacted large parts
of the country,

with 35 districts affected

and more than 190,000 houses
damaged or destroyed.

The floods displaced
tens of thousands of people

and caused clean water
and food shortages.

Disease and infection
is an ongoing problem

with all flooding,

but particularly
in lower-income countries.

Floodwater mixes
with sewage and animal waste.

Direct contact
with these polluted waters

increases the risk
of waterborne diseases

such as wound infections,
dermatitis, conjunctivitis

and ear, nose and throat
infections.

Floodwater can also contaminate
sources of drinking water,

a major risk factor
for outbreaks

associated with
waterborne diseases

such as typhoid fever,
cholera,

leptospirosis and hepatitis A.

Mobile phones have turned
into the ideal tool

for alerting populations
due to their extensive use.

The most important thing
for protecting lives

during a flood event
is early warning.

If people are aware
of the event ahead of time,

they can take precautions.

SMS messaging used
in Bangladesh

is a fast and efficient way
of spreading timely warnings

to large sections of
the population quickly

and more efficiently than other
communication infrastructure.

India, however, struggled
to get the message out.

Imagine the misery
people went through.

If we had
an early-warning system,

a lot of lives
could have been saved,

people would have moved
to safer places.

The help has to come
from government,

and I’m very skeptical
that it will come

in the quantities
that it is required.

So we are doomed.

Global forecasting centers
are able to provide

the science and forecast
capabilities

to individual governments
and authorities,

but it’s up to the local
authorities and governments

to provide the warning
to individual people.

Even with evacuation
instructions,

populations need
somewhere to evacuate to.

Infrastructure is important.

When the floods hit India,

many chose to stay
in the affected areas

to protect their homes
and belongings.

Evacuation efforts
were hampered

by the sheer number of people
affected

and displaced by the flooding.

Forty-one million people
were affected that year.

It’s very difficult to provide
aid to that many people,

particularly in areas where
the existing infrastructure

is weak or limited.

With as much as a third

of Bangladesh underwater,

humanitarian efforts
were severely challenged

and the 2000 medical teams
deployed

were only able to do so much.

One of the biggest problems
with floods

is you don’t actually see
some of the worst devastation.

We see helicopter pictures
of people standing on roofs,

but the people who are dying,

the people
who are really injured,

perhaps we don’t see
because they’re not reached

by the rescue efforts.

With rising sea levels,

Bangladesh remains
at considerable risk

of future flooding.

In recent years,
the building of flood defenses

has intensified,

with the World Bank earmarking

two billion U.S. dollars

to fund
one of the largest programs

of building and repair of
existing dikes and embankments,

thought to protect
up to 42 million people.

Embankments are not the most
effective flood defense.

They do damage to the ecosystem
and can fail.

They are, however,
more affordable

than other
more engineered solutions.

Bangladesh is
a densely populated country

with tens of millions of people
living close to sea level.

If sea levels continue to rise

and floods can’t be prevented
by physical defenses,

we could see
the rise of flood migration.

Large populations of people may
be displaced from their homes.

Those that rely on the land
for their livelihoods

could experience
extensive financial losses.

Sea level rise

and the dramatic floods
that follow

could displace
millions of people.

This could cause a refugee
crisis in affected regions

which could spill over
to neighboring countries

as populations move
from the flood-ridden areas.

In terms of limiting
climate change

and developing
better flood defenses,

the stakes are high.

International responses
are needed

because floods are
a transnational

rather than local issue.

There’s nothing we can do
to protect every single person

from every single flood,
so we need to have

preparedness actions in place.

Those can be evacuations,

they can be temporary barriers
that come in,

they can be other ways
of diverting floodwater

into other areas.

The 2017 floods in Texas

received extensive
media coverage in the West.

Unfortunately,
the dramatic scale

of the flooding in South Asia
wasn’t fully represented

in the Western media

compared to smaller
Hurricane Harvey.

Because a dramatic flood was
already happening in the U.S.,

it seemed they didn’t need
to cover another flood.

Natural disasters like floods
occur around the world,

impacting both
rich and poor countries.

The vast majority of casualties
in these events

happen in the developing world.

This happens
for several reasons.

Wealthy countries have
more money available

to invest in flood defenses,

potentially reducing
or even stopping the flood.

Better infrastructure
and rescue services

limit the loss of life

and financial insurance
is usually in place

to support rebuilding
after the waters recede.

Poorer countries lack
many of these things.

They also often don’t have

the same degree
of urban planning,

with shantytowns built
without design

or regulatory
planning approval.

Populations in lower-income
countries are more vulnerable,

with more people living
in the wrong place.

A strong communication
infrastructure is often lacking

and it can be more difficult
to get the word out

to warn of the need
to evacuate.

Also, poorer people may be
less able to evacuate.

They may not have the means
to travel quickly enough

or have anyplace to go.

The statistics confirm
this story.

The floods of 2017
killed 88 people in Texas,

but over 1200 people died
from the South Asia floods.

Water is required for life

and flooding is
a natural climatic event.

Floods can be relatively benign
and easily managed.

Sometimes they are
a net positive,

irrigating the land
and washing away pollutants.

However,
in many parts of the world,

floods can be much more deadly,

particularly for those living
in poorer areas.

In many locations,
human activities

such as agriculture,
climate change,

deforestation and urbanization
have added to the flood risk.

So we see every year
these huge floods come through,

and it’s very worrying.

So we think that there
is some kind of link

with climate change.

And we see, of course,
more people in the way

as populations move
into more at-risk areas.

They need to think about
adapting to these big floods.

We know that it floods already,

but we think it’s going
to get worse.

The sheer power and quantity

of water involved
in some of these disasters

makes elimination
of risk impossible.

The quantities involved

can be beyond human ability
to prevent.

In many cases, people live
in flood-prone areas

because they have to.

As world population grows,

countries become more crowded,

people have less choice
about where they live and work,

resulting in
more and more people

living in areas
of high flood risk.

If a flood can’t be prevented,

better planning is needed

to ensure populations
are more able

to withstand
the hardships of flooding

and are in a stronger position
to bounce back and recover.

Floods are a deadly disaster
that can’t be prevented.

With forethought,
planning and investment,

there are better ways
to avoid injury

and loss of life associated
with these terrible events.