Tennessee Tech develops sensors to help detect flooding

At least 35 states now have mesonets — sensor systems that track environmental conditions like soil moisture and barometric pressure in real time.

TENNESSEE, USA – To respond to the risk of dangerous flooding that follows extreme rainfall events, climatologists, engineers and emergency managers rely on environmental data – data that is scarce in Tennessee. For example, the State largely lacks, outside of rivers close to urban centers, flood sensors.

This risk increases as the climate warms

“Rural areas are where we have no eye on the ground,” said Alfred Kalyanapu, professor of engineering at Tennessee Technological University.

The problem is similar to the lack of Mesonet in Tennessee, a system of sensors that track environmental conditions such as soil moisture and barometric pressure in real time. At least 35 states now have mesonets, which scientists say improve extreme weather forecasting.

In 2017, Kalyanapu decided to look into flood-specific sensors that can complement mesonet data. He worked with students to create a low-cost solution to what he discovered was a significant infrastructure shortage, often viewed by heads of state as a funding challenge. He garnered initial support for the project through a grant from the US Geological Survey.

His team has built ultrasonic devices that sit vertically above a body of water. Each device sends out sound waves at a frequency of 42 kilohertz and records the time it takes for the sound echo to reflect. This provides an accurate measurement between the sensor and the water, and it can be recorded at 15 minute intervals.

If the data points start to increase, there is likely a flood. Most of the time, these graphs will look boring.

Yet data can help us better respond and prepare for inevitable disasters, Kalyanapu said. It can shorten the time between official warnings and danger, allow scientists to recreate a flood event in models, and help emergency officials understand risk.

“You can’t just blindly say, ‘Hey, I have a sixth sense that tells me it’s going to be flooded,'” Kalyanapu said. “You need data to inform your decisions.”

These flood sensors cost around $500, Kalyanapu said, while a commercial equivalent typically costs around $20,000. To test their accuracy, Kalyanapu placed one of its sensors next to an official USGS gauge.

“Preliminary data shows it’s as good as commercial sensors, especially considering the cost,” Kalyanapu said.

Any community can contact the university to request a sensor. The city of Waverly, which experienced Tennessee’s second deadliest flood to date, installed two.

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