Rivers - Friend and Foe Human Planet

Only one creature has carved a life for itself in every habitat on Earth.

That creature is us.

All over the world, we still use our ingenuity to survive in the wild places,

far from the city lights, face to face with raw nature.

This is the Human Planet.

Humans have always been drawn to rivers.

Rivers flow through every environment,

bringing us the essentials of life -

fresh water...

..food...

..and ready-made highways.

But what rivers give, they can also take away.

They can flood,

freeze...

and sometimes disappear altogether.

Rivers force us to take great risks.

These are remarkable stories of survival

from the most unpredictable habitat of them all.

It's the monsoon season, and the mighty Mekong,

Southeast Asia's greatest river, is in full flood.

Between Cambodia and Laos,

the Mekong current creates the widest rapids in the world.

The Khone Falls are great for fishing, but also very dangerous...

..as Sam Niang, a local fisherman, knows all too well.

Migrating fish get trapped here, waiting to get up the rapids.

Sam Niang has to risk his life to catch them.

He has a family of seven to feed.

He starts by fishing from the riverside, near his home.

During the monsoon, the Mekong swells to 20 times its normal volume,

which brings more fish, but makes them much harder to catch.

After a morning, his net is still empty.

There is another option - an island out in the main rapids.

But to get there, Sam Niang must take his life into his hands.

In the dry season, he built a high wire across the rapids

out of old cable and bits of rope.

At this time of the year,

these rapids have nearly twice the flow of Niagara Falls -

more than 11 million litres a second.

He makes it to his favourite fishing perch.

Turbulent currents corral the fish,

and Sam Niang soon lands his family's supper.

Though the fish are plentiful here,

the most he can carry back is a few kilos at a time.

Any more, and he might lose his balance.

Today, Sam Niang won his battle with the Mekong.

Tomorrow, to keep his family fed, he'll have to fight it again.

It's not just the power of water that makes rivers dangerous.

It's their erratic nature too.

Reading a river correctly

can mean the difference between life and death.

The Zanskar valley is a hidden world on the edge of Tibet,

in the heart of the Himalayas.

In winter, it's cut off by snow.

All roads in and out are impassable.

Stanzin needs to get his two children to school,

but the nearest school is 100 kilometres away,

and the only way to get there

is to walk down a frozen river.

It's a six-day trek, so dangerous it's got its own name -

the Chadar - the blanket of ice.

They'll have to brave sub-zero temperatures,

avalanches and freezing water.

Term starts in a week.

It's time for the school run, a formidable trip for 11-year-old Dolkar.

Dolkar's 14-year-old brother, Chosing, is coming too.

The family prepare for the journey ahead.

Their mother has knitted them thick woollen socks to protect them.

The brother and sister depend on their father's courage and skill.

This has to be the most perilous school run in the world.

The spring melt seems to have started early, which worries Stanzin.

Stanzin has to make sure the ice can take their weight.

And his expertise is tested immediately.

The danger is not only underfoot. There's another threat - avalanches.

Seven days ago, an avalanche killed a man on the Zanskar river.

The unusual spring sunshine has brought another problem.

The river's current has already melted the ice.

Stanzin has to find a way past the barrier.

The only way around is a narrow ledge.

The ledge is barely 20 centimetres wide and covered with snow.

There's a ten-metre drop to the freezing river below.

The ledge ends with some metal pegs to climb down.

Chosing makes it.

Now it's Dolkar's turn.

They mustn't delay.

Night is falling fast, and the temperature will plummet to minus 30 Celsius.

Luckily, Stanzin knows a cave nearby.

The children need their sleep.

The most dangerous part of the Chadar is still ahead.

It's not all hard slog.

But Dolkar's fun can't last.

As the smallest, she's the first to feel the cold.

She starts to lag behind.

One little girl on a melting ice river,

among the greatest mountains on Earth.

Now for the final leg.

The melting ice has left just a tiny shelf.

It's thin. Stanzin is worried it won't take their weight.

As he advances, the ice starts to crack.

With the ice weakened by Stanzin's weight,

the children have to brave it on their own.

Dolkar's made it, now for Chosing.

Thanks to their dad's expertise, the children have survived the Chadar.

Six days out on the ice river.

The Himalayan town of Leh, journey's end for the children.

They rush straight to the school.

There's just enough time for a goodbye.

BELL CLANGS

Stanzin now faces the return journey on his own.

Melting river ice doesn't just make travelling harder.

When frozen rivers break up, tonnes of ice start to flow,

a potential disaster, even in the heart of a modern city.

In the Canadian capital, Ottawa,

spring melt turns the Rideau river into public enemy number one.

The danger point is a footbridge on a frozen waterfall...

..a bottleneck where the Rideau flows into the Ottawa river.

It's late February, and the ice is melting here too.

Ice blocks are in danger of forming a dam,

which might lead to devastating flooding.

A natural threat that needs a daring human solution.

Meet the ice-dam busters!

Their job isn't just to predict nature,

they have to beat it!

There are thousands of tonnes of ice behind the bridge, up to a metre thick.

The team needs to break it up to keep the river flowing.

Stage one - cut the ice into long strips.

They're still too large to flow under the bridge, so, for stage two,

the team uses a more persuasive force...

Now!

..hundreds of kilos of dynamite.

Hup!

Bite-size pieces now flow easily under the bridge and over the falls.

The centre of Ottawa is safe for another year.

The world's largest rivers bring the most danger to our lives.

Their floods can be devastating.

They often happen without warning,

and there's nothing we can do but try to escape.

In Bangladesh, tens of millions of people

can be displaced when the Ganges and her tributaries burst their banks.

The river is so strong, it regularly changes course,

brushing land aside as it goes.

A month ago, Mohamed Jaleel's village was 100 metres from the bank.

Today, his house is about to be swept away.

He and his neighbours have only minutes to move his home.

The rest of the villagers look on, helpless,

as the rising river obliterates their land.

In South America, floods can be so huge

that the entire year has to be spent planning for them.

In the Amazon basin, one mother prepares for the rising waters.

Jarnia lives by the Rio Negro in Brazil.

It's November, the dry season, the time of plenty.

Fish are so easy to catch,

she even has enough to feed the local river dolphins.

But in six months' time, when the flood water invades,

all these dolphins and the fish with them

will disappear into the flooded forest to breed.

When the fish are gone, feeding her large family will become a nightmare.

Surviving such hard times means thinking ahead,

and Jarnia has a four-stage plan.

Stage one is collecting turtle eggs six months before the floods arrive.

River turtles lay thousands of eggs in the dry season beaches,

which they leave to hatch.

Turtles are a reliable source of protein when the waters rise,

so these eggs are precious.

Back in the village, it's time for stage two.

Jarnia reburies the eggs in her turtle nursery.

In the wild, many eggs would be eaten by animals...

..but here they'll be safe.

By March, four months later, 3,000 eggs have hatched.

It's stage three - release day!

It's time to release the babies.

But will enough of them survive to feed the village in the floods to come?

It's June, the height of the rains.

The river rises seven metres.

Jarnia's village is transformed.

The forest is flooded,

and the nearest dry land is more than six hours' rowing away.

Jarnia's family is now marooned by the greatest annual flood on the planet.

Time for the final stage.

Jarnia and her sister Dora prepare to go turtle-hunting.

Jarnia's husband, Francisco, makes them a turtle-hunting spear...

..and then the two sisters set off in search of food.

Will their hard work bring dinner to the table?

At first, it's not looking promising.

Then Jarnia spots one.

Her preparation's paid off.

She'll be able to feed everyone.

Jarnia's foresight has pulled her family through another difficult flood.

THEY SING

Some river creatures pose a direct threat to humans.

The Zambezi river in Africa is used by elephants, crocodiles and hippos,

some of the continent's most dangerous animals.

Fisherman Josphat and his brothers have found a safe,

if slightly hair-raising, fishing spot,

a place where they can catch lunch without becoming dinner themselves.

The place they're heading for may be safe from crocodiles,

but it does have a drawback.

The reason Josphat's fishing pools are far from safe

is their precarious position...

..at the very top of Victoria Falls.

Josphat's bravery and skill

enable him to fish where no animal dares to venture.

People can overcome floods and even learn to fish on giant waterfalls,

but there's one face of a river that's virtually impossible to survive.

When a river dries up and disappears, all life drains away.

Lemagas is a Samburu camel herder in northern Kenya.

No rain has fallen here for eight months.

It's a severe drought, and the Milgis river has vanished.

Lemagas has been forced to range deep into the desert,

searching for fresh food for his precious camels.

Now they are far away from home, and they've run out of drinking water.

Not even the camels can survive this long without a drink.

Lemagas knows there is water here, hidden underneath the river bed.

But how can he find it?

The Samburu have learned to rely on another nomadic creature,

one that usually travels at night.

While Lemagas and his camels rest,

not far away, some giant water-diviners are sniffing out the river bed.

An elephant's trunk - its nose - is far more sensitive than a human's...

..which means it can tell where the water table is closest to the surface.

Elephants must drink 100 litres a day

and can suck up eight litres of water at a time.

Having drunk, the elephants leave before dawn.

Early next morning, Lemagas and his camels are on the elephants' trail.

Even a dry river bed holds water if you know where to look.

They sing their thanks to the gods...and the elephants.

A few days later, Lemagas finally returns to his village

with its permanent deep well.

He doesn't forget the help he's been given in the wild.

The first thing he does is to bring up precious water,

not just for his herd and his family, but for his wild friends too.

He doesn't forget his nocturnal water-diviners, for without them,

Lemagas and his camels could never survive

when they're far away from home.

Over 4,000 kilometres away, in Mali, another dry river,

a tributary of the Niger,

is forcing one man into making a difficult decision.

His name is Ouseman, and he's a master mason in Djenne,

an ancient city made entirely of river mud.

His job is to maintain the city's mosque,

the biggest and oldest mud building in the world.

It's the heart of Ouseman's culture.

Ouseman's problem is this - every year the mosque needs

a fresh coat of mud to protect it before the rains arrive.

Down in the dry river bed, the mud is blended with rice husks,

and then left to ferment.

But this year, the mix hasn't reached the right consistency,

and now the rains are almost upon him.

Dust storms are blowing in,

the first signs that the wet season is about to begin.

The sacred building desperately needs a new storm-proof skin.

Two days later, Ouseman and his friend Ibrahim return to the river.

THEY CHAT

It's a big decision.

Word spreads fast, and everyone comes down to help.

Everyone in Djenne has been waiting all year for this special day.

The built-in palm logs are perches for the plasterers.

The whole town mucks in to protect the mosque for another year.

There's been a mud mosque in Djenne for 700 years...

..the sacred heart of a city fashioned from river mud.

CHEERING

Our relationship with rivers is never easy.

Their waters can give us so much

but can also take everything away.

We will always be at the mercy of their wild and unpredictable nature.

But one culture has found an inspiring way of mastering their savage rivers.

In northeast India, a giant cliff leads up into a hidden world...

..Meghalaya.

Nearly two kilometres high and buffeted by monsoon storm clouds,

this is possibly the wettest place on Earth.

Once, 25 metres of rain fell here in a year, the world record.

Living here poses an unusual problem,

and it's not just keeping dry.

Nearly all the rain falls during the summer monsoon.

Rivers switch from gentle streams to raging torrents.

They become wild and unpredictable and almost impossible to cross.

Harley and his niece Juliana are busy cultivating a cunning solution.

30 years ago, Harley planted this strangler fig

on the river's edge, and today, he's teaching Juliana how to care for it.

The fig's tangled roots help to prevent the bank being washed away.

He teaches Juliana to coax the roots across what is now just a stream.

When they reach the other side, they'll take hold there.

This is the basis of a structure that will survive any deluge.

A living bridge.

It's an epic project that no man can complete in one lifetime,

so Harley is passing on his knowledge to Juliana.

Each year, Juliana will need to tend the roots, making them stronger.

If she stays and completes her bridge,

it will become part of the commuter route here,

a network of dozens of living bridges that connect the valleys of Meghalaya.

Some of them are many centuries old.

There are even double-deckers.

With Juliana to look after it, the future of this young bridge looks secure...

..sustainable, living architecture

that will live and grow for generations...

..one of the very few examples in the world

where humans have come up with a successful and natural solution,

a way of working with nature

to overcome the problems a wild river can cause.

For the Human Planet Rivers team, filming on the Mekong river

at the height of the monsoon raised many challenges.

Mainly, how do you capture a remarkable event without losing your camera,

your crew or your star fisherman, Sam Niang, to the river?

The Khone Falls have more water flowing over them

than any other waterfall in the world.

A narrowing of the mighty Mekong river funnels the migrating fish

and provides a dangerous, if lucrative, opportunity.

The crew's here to capture the extreme lengths

that locals will go to catch fish.

Sam Niang is lucky. He has access to his own small island for fishing.

But to get to his prime spot, he must risk life and limb.

To capture the spectacle of Sam Niang's high-wire feat,

the crew have chosen a gadget that runs on wires

and that controls the camera electronically, known as a cable dolly.

And the idea is, it's one of our most exciting and sought-after shots,

so we can follow someone walking across the tightrope,

so the camera moves with them and then pulls out to reveal the angry water.

But rigging such a hi-tech system over a raging torrent

is no easy feat, and it requires a specialist rigger.

We're just trying to get the cable across for the dolly,

so the local guy's just shimmied across the wires, as he does every day.

Whilst Tim works on the cables, the rest of the team

concentrate on filming the rapids from every other angle,

even shooting in the rapids themselves.

I'll just go here. It won't be a long run.

It'll take two or three minutes.

Mick O'Shea was the first man ever

to navigate the entire Mekong, from Tibet to southern China -

just the man to capture a fish-eye view.

But even he succumbs to the full force of the Mekong in surge.

His kayak is sucked under by the powerful current and swept downstream.

After a few worrying minutes, Mick re-appears, back in control,

safe but shaken.

With new-found respect for the Mekong's power, the crew stick to solid ground.

Using a four-metre jib, they follow Sam Niang

as he negotiates a treacherous rocky outcrop to cast his net.

Over and down, OK? And on... Good.

By now, Tim has the rigging ready for the dolly.

Do you want this up there?

There's a massive cloud come over.

THUNDER RUMBLES

But no sooner than it's in place, the heavens open.

It's the last thing they need.

Dolly filming stops for technical and safety reasons.

There's just a little spot of rain. I think rain's stopping play!

-Cos electronics survive the rain well(!)

-Yeah.

THUNDER CRASHES

The next morning, it's clear that, as feared,

water has got into the electronics.

So what's gone wrong with it now?

So the new, modern technology is ousted by the old-school way.

I'm going to go up there now and, um, put the camera on!

Oh, my... Whoa! OK.

The crew finally get the cable dolly working, so now it's time to get creative.

The light, the dolly, the safety team and, most importantly, Sam Niang,

all have to work in unison.

Go!

We turned it the wrong way.

OK, Tim.

No.

Nearly, nearly.

Bring it all back, yes.

Go.

No. Still no!

Sam Niang looks really happy, though, doesn't he?

My heart's in my mouth every time he has to go over that rope.

You look really happy, and I'm really worried!

The sun breaks through the clouds, and finally it all comes together.

Yay, we've got a keeper!

That's great!

Thanks very much, you.

Yeah!

What a relief.

Despite the odds, the Human Planet team have triumphed.