- I'm Frank Graff in Asheville.

Coming up on "Sci NC," the science behind the devastation of Hurricane Helene, what happened, and what it might mean for the future.

That and more on "Sci NC."

- [Announcer] Quality public television is made possible through the financial contributions of viewers like you, who invite you to join them in supporting PBS NC.

[gentle music] [gentle music continuing] - Asheville had gained a reputation as a climate city, not just for the government agencies and universities and nonprofits that were based here working on the issue, but also as a kind of sanctuary from its adverse effects.

Not anymore.

Producer Evan Howell talked to one of those scientists, who explained how the accurate tracking and prediction of hurricanes is important for protecting people not only on the coast, but hundreds of miles inland.

- [Evan] The river has receded.

What Hurricane Helene left in its wake has left residents stunned as to where to start with the cleanup.

Areas like the River Arts District in Asheville were nearly wiped away by the French Broad River.

- That's like 25, 27 feet or something like that.

- Yeah, our heads would definitely be underwater right now.

- [Evan] Carl Schreck knew it would be bad, just not as bad as it turned out to be.

- Friday morning of the storm, as it was approaching, I was getting text messages from a friend at the National Hurricane Center saying, "You're about to see some really crazy stuff.

The eyewall is headed right for you."

And this was just as power was out, cell phone was already starting to die, so I couldn't watch the radar to see where this storm was approaching in the hours and minutes before it came.

So it was really scary.

- [Evan] While we've always had hurricanes, Schreck says things are different because of climate change.

He says as the Gulf of Mexico gets warmer, it tends to serve up better conditions for systems to form.

- Hurricanes are especially efficient at wringing that extra moisture out, so they're causing the heavy rainfall like we saw with Helene, was even heavier because of climate change.

Also down at the coast, we know that sea level is rising.

So anytime you have a storm pushing storm surge onto the land, it's starting from a higher level.

You're gonna get even more storm surge just from that additional sea level rise that we've already observed.

So those two things, we're really, really confident about.

[somber music] We think probably we're getting about the same number of storms as we used to, and we're not really gonna get more of them, but the ones we get are probably going to be stronger than they used to because the ocean is getting warmer.

And the ocean, that provides the fuel to make these hurricanes.

[suspenseful music] - [Evan] Helene made landfall along the Florida coast September 26th as a category four hurricane with sustained winds of 140 miles an hour.

It weakened to a tropical storm as it moved northward and inland, but brought more water than anyone had ever seen in a weather event in state history.

By the end, Helene had dropped an estimated 40 trillion gallons of water on the region.

- So anytime it rains, it's raining harder now than it would have 100 years ago.

- [Evan] But climate change alone isn't what made Helene so devastating.

Call it bad luck.

Meteorologists call it a predecessor event or rain system that happened to hit the area just before Helene arrived.

It truly was the perfect storm, and not the good kind.

- All that moisture from the hurricane coming up, running into a cold front that makes it rain, running into a mountain that makes it rain even more, and then you have it raining on either side of the mountain, and all that rain's going down into a valley, that valley is going to flood very quickly with all of that rain coming together.

- [Evan] All these questions about weather and climate make understanding trends and global event monitoring crucial.

- I don't even know where you begin to clean this up.

In these reports we talk about extreme weather, we talk about where it's occurred, what's happening, how it compares to the historical record.

That's part of what we do.

We also track billion-dollar weather and climate disasters, of which this will likely be one of those disasters.

- [Evan] Karin Gleason says monitoring rainfall itself is a fundamental part of what they do.

And what they know best about hurricanes and climate is that they know hurricanes are getting wetter, and they know that as the climate warms, there's more water vapor and more moisture in the air.

- And then we have such, you know, varying topography in western North Carolina, that 16 inches of rain in one place can be 6, 9, 12 feet of rain in another because of the way the water runs from a high location to a low location.

And that creates intense, very rapid flash flood events.

So really, having the one-two punch of this predecessor rain event followed by Helene really made this particular event as catastrophic as it was.

- [Evan] What was this?

- This is my roof from the building block building over there.

- [Evan] Craig Weis has worked in high-end renovation and green building since 1982.

He says they're looking at other locations for his woodworking business in the area, but won't be returning here.

- That floated off with my solar panels and the pitched roof, as well as the U-Haul trailer that had all our high-end equipment in it, and washed away when it went up to 29 feet.

- [Evan] What are you feeling right now after walking through this?

- Well, you know, it's like what are we gonna do?

- [Evan] Gleason says it's an art to take the complexities of science and data they collect and explain it in a way that people quickly understand.

- You know, we try to make it as relatable as possible because that's the point.

You know, we're trying to communicate science to people and tell them why this all matters.

- [Evan] Helene left a swath of destruction not seen in over 100 years, and officials say the cleanup costs may top $50 billion by the time it's done.

But these costs in no way factor in the human element.

For Carl Schreck, the experience of seeing face-to-face what he has studied for decades suddenly come to his doorstep is something he won't forget.

- My children go to school with some kids that actually lost their lives in the hurricane, so actually knowing people that were so incredibly affected by it is really heartbreaking.

[somber music] - Residents of western North Carolina are no stranger to weather-related events, snowstorms, ice storms, rainstorms, and yes, flooding caused by rainstorms.

But folks here, and scientists, all say Hurricane Helene was a totally different event.

- [Elisha] The first mudslide happened and then about 30 minutes later, the second one happened, and then the road, it went down.

- [Frank] And Elisha Richardson's house became a kind of island in the middle of flowing mud, water, and debris.

- We were trying to keep an eye out for tornadoes.

So we were actually out here when the first one happened, and it just sounded like a rolling rumble, you know, as it was just coming down, just like a bunch of dirt just kind of tumbling down the mountainside, almost like an avalanche, but with your mud and everything.

It definitely put off a sound.

I was thinking wow, this is insane.

I would say the only time I was scared was when my husband was out here and the second one happened and he almost got, you know, like it compromised him.

I was just like oh my God, you know, he almost got hurt.

- [Frank] Landslides scarred North Carolina's mountains.

It's as if a giant monster scraped the hillsides with its claws.

The US Geological Service reports more than 1,500 landslides in North Carolina associated with Hurricane Helene and the heavy rains that fell for several days before the storm arrived.

Some landslides are large, some small.

Landslides ate away at the fill dirt beneath road beds, washing out hundreds of roads.

Engineers are assessing the damage.

That repair bill will run into the billions of dollars.

- My first impression, it's gonna take some type of retaining wall and reinforce it and get this thing back safed up because the guardrails gotta be removed, shoulder rebuilt, and then the guardrail reinstalled.

- [Frank] Landslides took out businesses as well.

[somber music] Hoyt Johnson's mountainside hotel, the Big Lynn Lodge was spared.

So he opened the doors as a shelter for storm victims and first responders.

- People can come see what I call the new mountains, the new look.

- [Frank] I was gonna say, what do you mean?

You said that a couple times, the new look, the new mountains.

- Yeah 'cause it's definitely different.

Where there used to be mountains, it's washed away.

The creeks run different than they used to.

Or businesses, unfortunately, are gone.

So it's definitely new mountains, you know, it will take years to fix.

[gentle music] - [Frank] The images are terrifying.

So what happened?

First, let's define what happened.

- So the term would be for out in western North Carolina, would be mud flows.

If it's really rich in fine grain materials, silts and clays, or probably a better term is debris flows 'cause there's boulders, and trees, and mud, and everything in between that's coming down.

- [Frank] Debris flows, or landslides, require two things, gravity, that's obvious, but they also need a slope that is steep and long.

- But once you get up in the Upper Piedmont and then into the Blue Ridge, now we have slopes that some of them are over a kilometer long or 5,000 feet long.

There's lots of vertical relief between the top of the ridge crests and the valley bottoms.

Those slopes are steep.

They're at or near what we would call threshold hill slopes.

So they're at about, essentially, as steep as you can get without material moving down them.

And it rains tens and tens of inches within a short period of time on soils that were already fairly wet because it had been raining in the preceding days.

Then this is what we would expect from the landscapes of the Southern Appalachians.

Water's percolating through this, through the soil on the hill slope.

And then it intersects the bedrock underneath that soil column, which is maybe three to six feet thick.

And then the water can no longer penetrate into the rock, so then it starts flowing along the rock, the rock soil interface, and the soil column loses coherence, and then that whole mass starts to slide down.

If it's oriented towards a channel, it slides down into the channel and then that's where you transition from a landslide into a debris flow.

Typically, the debris flows will start up high near the ridge crest.

The soil prism itself fails, starts to slide down into a channel where there's water flowing.

Then it bulks up, and that channel already has a lot of debris in it, rocks and wood.

Once the landslide enters that channel, it combines with the water and the debris that's in that channel already.

And then that starts snowballing, essentially, and morphs into a debris flow that then is traveling at 30 to 60 miles an hour.

But we're not surprised that this type of hazard happens in the mountains.

It's what we would expect, and it's why North Carolina Geological Survey has a group that's tasked with identifying locations where landslides have happened in the past, and then thinking about where are other places where they may have not triggered in the last rain event, but where are other places that have similar characteristics in terms of slope steepness, soil thickness, certain rock types that may be favorable to generating landslides and debris flows, and then generating these maps that can then be used by county or state emergency management folks.

- We just have to be prepared for what is here and what may come.

We all can't run to a different place.

There are ties, there are generational homes.

There's a real sense of community in a lot of these places.

So we are accepting a certain amount of risk when we live in these places, but we can be smarter about how we live with this risk.

- So we knew it was gonna flood, we just didn't know how much.

[gentle music] - [Frank] Over in Old Fort, the Mountain Gateway Museum remains standing despite Mill Creek washing the debris from nearby landslides through the town.

The 1930s home that houses the museum was built during the Depression, out of rocks taken from the river.

- [RoAnn] You know, we've been lucky with this rock building.

It was well built.

- [Frank] But she admits there is a risk to living in a mountain area she loves.

- When Mother Nature gets upset, you know, she's gonna destroy whatever she decides to destroy, no matter how well it's built or, you know, whatever safeguards you take.

- Hurricane Helene's floodwaters carried mud everywhere it went.

And that's why you can see the mud on the fence back there, and there's a layer of silt covering everything, and dust coming up from it.

But as the cleanup begins, we're finding those floodwaters carried more than just mud.

As producer Michelle Lotker explains, there are health and safety issues.

- Nobody alive has ever seen the river come up like that.

And it was actually the highest water level ever recorded in Asheville.

- [Michelle] Hurricane Helene brought a lot of water into the mountains of western North Carolina when they were already saturated by days of rainfall.

In some counties, over two feet of rain fell, causing rivers and creeks to swell their banks and washing people and their homes, businesses, and belongings downstream.

MountainTrue and local Riverkeepers are watchdogs of the watersheds of western North Carolina, and they work with their communities to protect surface and groundwater.

- When we're looking at water quality after an event like this, we're looking at a really broad spectrum of things 'cause it's really hard to point the finger at a single source after an event like this.

Anything that had rainfall on it is in the river now.

- [Michelle] Erica is Riverkeeper of the Green River, an outdoor adventure paradise for fly fishers, rafters, paddlers, and hikers alike.

The Green was dramatically reshaped by the storm.

Mudslides crisscross a switchback that goes down to the river.

Powerful floodwaters carried away riverside houses.

- This was property, land.

This was houses that lived all along here.

- [Michelle] And a popular river access called Fish Top is almost unrecognizable.

- [Erica] Actually, I'll give you a little perspective.

In between these rocks right here was the trail that you walked down to, gradually, to Fish Top.

All of this was wooded, trails through it.

And now.

- Wow, oh my gosh.

- And now-- - It's a cliff.

- It's a cliff.

It is a complete absolute drop-off.

- That is insane.

- And this is nothing how it was, nothing.

There was like a pool here, and then this sand that has come in, obviously, was not there, but I'd say maybe on the other side of the sand was like all game lands.

- Wow.

- So like all of that was wooded, so it's completely different.

I mean, it's kinda hard 'cause it was like so beautiful.

Like this is so, sorry, I didn't expect that.

Like it's, you know what it looked like.

It's just really hard to describe what it looks like.

- [Michelle] Erica has been helping Riverside residents like Brad test their well water to see if it's safe to drink.

- But do you let it run for a while already?

Okay, heck yeah, all right, awesome.

- [Michelle] Brad's wellhead was submerged under several feet of floodwater, which may have introduced bacteria or other contaminants.

- The water sat right here for five or 10 minutes and then it came up to right to the siding.

And that's when I was like well, it's going in, you know.

But it sat there for about five minutes and then dropped.

I woke up at nine o'clock because my septic had back pressure on it.

The toilet gurgled.

That woke me up.

I, you know, sat up and looked out the window, and there was stuff floating across the yard, and I was like oh no, the water's actually really high.

The water came up, probably seven feet in about 20 minutes here.

We were able to watch the whole river left bank kinda just disintegrate, you know.

There was a 40, 50-year-old tree falling in about every 10 seconds.

You'd just hear the snap and the fall.

I moved here because of the Green River Narrows.

It's one of the best pieces of, you know, Class 5 white water in the world, just a beautiful, beautiful place to be.

Everything is different in there, nothing the same.

- I'm gonna test it here.

I want you to go inside and test it from your house.

- Okay.

- Woo, 1:11, make a wish.

So I want you to take a Clorox wipe and take the little aerator off of the bottom of your faucet.

Wipe it off real good.

Let your water run for like a minute or two, and then you're gonna fill up this bottle with just your water to that line.

- [Michelle] Erica and her Riverkeeper counterpart, Hartwell, in the French Broad Watershed, are helping people get access to free well-testing kits.

- Hey, how's it going?

- Good, how are you?

- Hey, good, I'm Hartwell.

We're in the Cane Creek Watershed in Fairview, and we're offering well testing for folks that may have had their well flooded.

We got a bunch of Riverkeeper colleagues that came to town, which is awesome, so we've been able to like divvy up the work.

We got folks in six locations around the watershed right now, all collecting well samples from folk.

Oh man, you're a star student.

- First one back.

- All right.

- [Michelle] For Riverkeepers who guard the health of their watersheds, seeing so much debris wash into the rivers they work to protect was devastating.

- At first it was like, this is heartbreaking, you know, I stood on the banks of the river and watched houses wash down, and gasoline wash down, and refrigerators, and, you know, I've worked a long time to protect and clean up the French Broad River, and it seemed ruined overnight.

But then going around to all these communities, it was really heartwarming to see the resilience of people, like people just coming together, checking on their neighbor, helping people chainsaw out of their homes, cooking meals for people.

In a time where I think we're supposed to be, like, hyper-partisan, nobody cares right now.

[laughing] - [Michelle] One place where people are coming together is in Marshall, where the French Broad River severely impacted buildings and businesses downtown and in the nearby residential community of Rollins.

Residents and volunteers have been working to remove debris and thick mud from buildings like Marshall High Studios, home to the studios of dozens of artists like Frank Lombardo.

- River was like more than twice our height over us.

You can see the water line on the bricks.

It got up to 20.08 feet.

It destroyed the first floor completely, and a lot of people lost everything.

And we had a foot of mud everywhere in the building.

I can show you in here.

- Yeah, you can see the-- - You can see the water line.

That's the water line there, yeah.

- [Michelle] Fortunately, engineers have certified the building as structurally sound.

Now they're working to raise money to rebuild the inside.

- It's a lot of work, but we've had amazing volunteers.

So happy, and proud, and grateful to be part of this community.

Yeah, like they're hustling nonstop every day, getting us what we need.

And we couldn't do it without everybody doing their part like that.

- [Michelle] Everyone doing their part in Marshall includes making sure volunteers have protective gear to avoid exposure to unknown hazards in the materials they're working with.

The staging area in local business, Nanostead's parking lot has developed a well-organized process to decontaminate people when they're done for the day.

People are being cautious during cleanup because they're not sure what was left behind by floodwaters.

MountainTrue and the Riverkeepers are working to test soil and water throughout the area to bring people information about any potential health and safety issues.

- We want to know what heavy metals are in there.

We wanna know what chemicals.

We wanna know what bacteria.

We wanna know what's in there so that we can give people accurate information and then do something to address it.

- [Michelle] With the help of visiting Riverkeeper teams, samples have been collected across the French Broad's watershed, including in Marshall.

And so far, Hartwell says the results have been a pleasant surprise.

- To see out of the sample only have two pollutants show up, only one kinda being to concerning to human health, and then the levels of that weren't super high, was very encouraging, in that, you know, one sample in the one location, a good sign so far.

- [Michelle] But efforts to clean up these rivers are only just beginning, and Hartwell warns it's going to be a long-haul effort that needs continued support.

- If this cleanup is left to groups like ours without significant resources, it's gonna be a long, hard recovery, and a lot of places are gonna go out of business.

We have to get that cleaned up, and we have to get that cleaned up pretty urgently for folks to be able to operate next summer, hopefully.

- [Michelle] In the Green, Erica is working with contractors to remove debris and continue to monitor water quality.

Fortunately, Brad's well came back clean, and E.coli levels in the Green River remain low.

But Erica is also worried about long-term impacts.

- This is not what we wanna see, right?

But like you envision her, like, in a new light.

She looks different, but she's still beautiful, yeah.

- Hurricane Helene's destruction was widespread.

Houses, businesses, public facilities, nothing was spared.

But as the recovery begins, we found a snapshot of everything happening in western North Carolina on one road just north of Marion.

[water rapids roaring] The raging floodwaters of the north branch of the Catawba River took out the Route 221 bridge connecting Marion with the Woodlawn North Cove community.

Ever seen something like this?

- This is insane, this drive that I'm about to traverse or attempt to traverse, we'll see how this goes.

- [Frank] While the concrete connection was destroyed, the connection between people and communities is still going strong.

You a little nervous?

Or you gotta get through, and so you just gotta-- - You know what, when we got duty to do, we just go do it.

- [Frank] So, while temporary and permanent bridges are planned, to keep that connection going, folks graded the riverbank just enough to allow vehicles to drive through the river.

- Well, I mean, it's just what you do when you live in the mountains and have to get somewhere.

You know, it's, we call it mountain ingenuity.

But the roads are tough.

We've made a couple spots like this to be able to cross the river to get to where we need to go.

But no, it's not easy sledding by any means.

I don't go very fast 'cause if you do, you're liable to, the river rock can be sharp, so if you go too fast, you're liable to pop your tires.

So it's better to be in four-wheel drive if you have it, and go slow.

You won't get stuck in the river.

You might get stuck going up the hill.

Well, when you live up here, you get used to some things, you know, and you live in the mountains, so you try to be as prepared as you can.

And, you know, we all have four-wheel drives or whatever, so we kinda get, I don't know, we're not to say used to it, you don't get used to anything like this, but you just keep going, you know.

If something's in your way, you move it, and then you go around or you go around it, one way or the other, right?

So that's kinda the way it is here in the mountains.

- [Frank] That spirit of just do it is found all around western North Carolina.

- I don't know that it's going to quite be the same.

It's gonna take a long time to rebuild, but the communities will come back.

They will be prosperous again.

- Everybody in town is fully behind everybody else in town.

There's no more us and them.

There's none of that.

- The sweetest, like, woman and her daughter, like holding some large rectangular device.

I'm like what is this?

And she's like, "Stop, stop, stop."

So I pulled over, and I could barely see her in my truck, and I reach over, and she hands me this, like, she was like Eastern European, and she handed me this like little pastry.

And she had a whole tray of them.

And I just like rode home with, like, trying not to well, eating this pastry.

It was so sweet, like the resiliency here, and people coming together is like, it's profound.

It's a lot of silver linings amongst all the, you know, negative situations.

- And that's it for "Scie NC."

Our thoughts are with everyone in western North Carolina impacted by Helene.

And we will continue to share stories as the recovery continues.

I'm Frank Graff, thanks for watching.

[gentle music] [gentle music continuing] - [Announcer] Quality public television is made possible through the financial contributions of viewers like you, who invite you to join them in supporting PBS NC.