Sinking suspicions: Predicting future disasters

If you lived on top of a sinkhole, would you want to know?

“When a house falls into a sinkhole, neighbors clamor for information. They ask if their house is next,” said Dr. Doug Gouzie, geology professor at Missouri State University. “It’s unimaginable and devastating, but I think they might not really want the answer to that question.”

Gouzie studies land formations, like sinkholes, and how water forms them.

“Your house being built on a plot of land doesn’t create a sinkhole. It’s not the weight of a structure,” he said. “The right conditions must already exist underneath the ground.”

He’s one of about 100 doctoral-level people in the country studying these structures. His goal: predict the next sinkhole site.

If you have a new sinkhole, people always want to know where did all the dirt underneath go?

Common themes

By investigating sinkholes, Gouzie finds similarities. Each finding moves him toward that major end goal – one he’s not sure will be reached in his lifetime.

His studies have revealed a variety of contributing factors. In a residential neighborhood where a sinkhole swallowed a house, he found a correlation between sinkholes and mature trees.

“Mature trees are very, very good at finding water,” Gouzie said.

Dr Doug Gouzie does research on current sinkholes and look for warning signs of spreading he wants to be able to predict future sinkholes before they form.

Dr. Doug Gouzie and graduate student Jordan Vega explore Smallin Civil War Cave. 

Roots often spread out to gather water. If roots fight their way through cracks in the underground rocks to find a reliable source, there might be a problem.

“If a tree happens to find a crack that leads them to a cave passage with a stream, that makes them happy. Then they grow better,” he said.

In this particular case, the owner had cut down a tree, but the stump remained. Gouzie said it’s unclear whether grinding out the stump, yanking it out or leaving it would lower the risk of a sinkhole.

Because the tree was now dormant, the roots shriveled up, leaving significant cracks in the rock. Anything like this, which funnels water underground, can make the ground vulnerable to caving in.

Once water finds a path, it will keep seeping through. You’re not going to create Fantastic Caverns in 50 years, but you can in a couple of million years.

How it works

About 20% of the United States is built upon limestone or other carbonate rocks, which are called karst lands. When rain falls, the acidity in the rain slowly dissolves that rock.

Gouzie likens it to a marshmallow in a glass of water. First the marshmallow gets goopier, then becomes marshmallow fluff and finally dissolves.

Dr. Gouzie working with a graduate student to collect water and sediment from local caves.

Dr. Doug Gouzie’s graduate students get hands-on experience collecting water and sediment from local caves to trace the paths of waterways.

When rain water hits the soil, the small soil particles can wash out through the dissolved holes quickly, he noted.

The appearance of the soil in your yard can tell a story, too. If you see areas with lighter soil while other areas stay a richer brown, something may be amiss. The lighter area may indicate the water has dissolved lime. Instead, the water is moving somewhere deeper.

“If I know where the landscape is draining into – where it’s going underground,” he said, “then I know where it’s washing the soil away. That’s where I’m going to find the next sinkhole.”

Dye tracing

Along with his graduate students, Gouzie spends many hours in caves across Missouri and on stream banks collecting water and sediment.

Jordan Vega, graduate student, works with Dr. Doug Gouzie to identify which waterways lead to which caverns. 

“Nature gives us the results that will help us predict what sinkholes or drainage areas are connected with which cave or spring underground,” he said.

One way they determine this is by placing dye in the streams – detectable by black light but not the human eye. Using an instrument with a very sensitive electric eye, the team can trace the dye’s path, even when the spring meanders underground.

As a kid, I just found water fascinating.

Director of the Missouri Geological Survey Joe Gillman appreciates how Gouzie’s work also seeps into other areas, such as water quality and public health.

“He’s addressing real geoscience challenges affecting people’s daily lives,” Gillman said. “His research routinely focuses on finding solutions for … not only his community, but also the citizens of Missouri.”

Further reading

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