The Tennessee Climate Office will evaluate the catastrophic flooding that washed away roads, bridges, and homes, and killed six people in the state’s easternmost communities.
JOHNSON CITY, Tenn. (WKRN) — The Tennessee Climate Office will evaluate the catastrophic flooding from Hurricane Helene that washed away roads, bridges, and homes and killed six people in the state’s easternmost communities.
“The impacts and the amount of rainfall was definitely pretty unprecedented in modern times. There were a few events in the early 20th century, over 100 years ago that may have been similar. It’s hard to say, with the lack of data,” said State Climatologist Dr. Andrew Joyner. “But this was definitely is a huge event, biggest in generations in this area of Northeast Tennessee, certainly in Western North Carolina.”
The office is based out of East Tennessee State University, the same part of the state now reeling from a major flooding event.
“Forecasts were pretty good with where that rain would fall and how big it would be. You just never know the types of impacts and how quickly massive walls of water and debris can move and the types of damage they can cause, I think that was… that would have been hard for anyone to predict,” said Dr. Joyner. “Just the impacts are so impressive.”
Researchers will now comb through data like rainfall and drone imagery to hone in on the historic nature of the flood.
“We got a little bit of imagery in Washington County, and we were able to compare that to some of… we’d produce some models for 500 year flood events. And the place that we were flying, the flood waters were beyond the 500 year extent, which fits,” said Dr. Joyner. “The this seems like a 1000 year event in many locations.”
According to the U.S. Geological Survey, the term “1000-year flood” means that, statistically speaking, a flood of that magnitude (or greater) has a 1 in 1000 chance of occurring in any given year.
“Probably, above a 1000 year event in Western North Carolina, but even in parts of East Tennessee, right at 1000 year event for rainfall,” said Dr. Joyner. “We’re getting the rain waters from areas that were probably closer to 2000 year events.”
The rain also fell when many communities were experiencing drought.
“Certainly, in the the channels of the rivers and the flood plains, there was no time for it to absorb but in other areas that were a little higher elevation, that probably did maybe prevent some reduced or mitigated the level of flooding a little bit. But that’s anecdotal. You know, not a lot of data on that,” Joyner explained. “But certainly the soil was very dry across the state, and across the areas that that got a lot of rainfall and had the capacity to to absorb a good bit of rain.”
The State Climate Office released preliminary precipitation data for the most impacted watersheds in the flooding from Helene in northeast Tennessee. They found the worst flooding occurred along rivers with headwaters in North Carolina. The office reported that while rainfall from Wednesday – Saturday was in the 5-10″ range in East Tennessee, the headwaters of the Watauga/Doe Rivers, Nolichucky River, Upper French Broad River, and Pigeon River had well over a foot of rain.
“(That’s what) makes this such a big deal: it’s the extent of the damage, not just a few communities, just so many communities along the rivers, which is where people settle,” explained Dr. Joyner. “That’s where we build, that’s where the farms are, and communities aren’t far from water. And in your mountain towns, there’s only so many places for the water to go, and it’s channelized, and it’s going to go quick.”
This week they’ll collect data along places like the Nolichucky River.
“Really to get good ideas for how has the river changed? Where are we seeing significant scarring, significant erosion, lots of bridges out, you know, what are the impacts there?” said Joyner.
Tennessee is no stranger to major weather events, including catastrophic flooding. That includes the 2021 flooding in Waverly and 2010 flooding in Nashville, which demonstrate how severe flooding can happen anywhere.
“You often see them happen on the news, and if it’s not in your community, then it’s hard to imagine something like that happening, even with Waverly. Certainly, we saw that, we worked on the state climate extremes report certifying that as the new 24 hour record, and a major event, but pretty localized a rural area, but just 60 miles west of Nashville,” Joyner explained. “That exact same event could have easily happened in Nashville. And if you look at the 2010 floods versus Waverly, it was almost double the amount of rainfall in a shorter period of time in Waverly compared to the 2010 floods in Nashville.”
The SCO was recently awarded a grant from NOAA to better understand state agency needs for climate data and to host a community resilience academy. They had already planned on doing so in East Tennessee and now they’ll be able to help people connect the data to reality.
“Now we’ve got this very significant event, and no one in this region had ever seen before. And so the opportunity to do the resilience Academy right after that is, I think, going to be huge in helping us understand the event better and how it fits into the larger climate context,” said Joyner. “Also helping community leaders understand, okay, maybe there’s some vulnerabilities here we didn’t think about or didn’t know and so how do we do a better job planning for those elements? And that’s really what we want to provide — those services and data. We’re not an activist or advocacy group. It’s really about here’s the data, here’s the services, and then what the communities can do with that information.”
He added that some their key goals for severe weather events is to evaluate them and help people understand the likelihood of them happening again.
“I think there’s definitely people that are impacted by flooding that thought they were perfectly safe. I mean, they were outside of the 100 year flood plain, and so they probably didn’t have flood insurance. They probably didn’t have those sorts of things and never thought about contingency planning for being trapped on a peninsula, because they didn’t think seven bridges would go out,” said Dr. Joyner. “Those are things that it’s kind of a worst case scenario, and you don’t often want to plan for those, or want to think about those, and because often they don’t happen. But the fact that it happened, I think, has really brought this to the forefront and made a lot of people realize that a large type of catastrophe like this is possible in our area.”