Cora Siebert displays the inner-workings of a “tipping bucket,” a specialized rain gauge that measures the rate of rainfall. Ten citizen scientists will monitor tipping buckets- the next step in creating a landslide warning system in Sitka. (KCAW/Rose)

Knowing how much rain is falling — and where — is an important information for researchers creating a landslide warning system. But gathering that data is not so simple: You need rain gauges that work around the clock, and a small army of citizen scientists to take care of them. Sitka now has both.  

Cora Siebert, the Geoscience Coordinator at the Sitka Sound Science Center, and Sitka High School science teacher Stacy Golden are scouting locations at Sitka High School to install a tipping bucket. Tipping buckets collect and measure the rainfall, but they’re a little more complicated than a rain gauge.

“You can imagine the inside kind of like a seesaw, and the seesaw has a bucket on each side of it, and the bucket is calibrated to hold one-hundredth of an inch of rain,” Siebert explains. “Once it’s full of one one-hundredth of an inch of rain it dumps it out, and then the other bucket can start filling up.”  

Siebert films Golden as she explains the pluses and minuses of one spot they’re considering. 

“The catch with this is we do have some overhang area. We have the edge of the building, so there’s this kind of nice gap in-between,” she says. “There are vehicles that come through this area so we wouldn’t be able to put it in the middle of the path, it would have to be off to the side of back in this muddy area.”

While this is a fun project for Golden’s field science class, the buckets also collect important data about Sitka’s rainfall that will be incorporated into the landslide warning system that’s being created in partnership with the National Science Foundation and the Rand Corporation. 

There are 10 tipping buckets, most about two miles apart, to measure the rate of rainfall, and each is hosted by volunteer citizen scientists. Siebert says the goal is to identify microclimates around Sitka. 

“Microclimates are how the weather might vary from neighborhood to neighborhood,” Siebert says. “That’ll help us understand how precipitation rates vary on a finer scale than just, ‘Oh! Sitka’s getting rain,’ which we hope will help with landslide prediction. Neighborhoods can start to understand the weather more locally to them and make decisions on what kind of risk they’re willing to take in for themselves, instead of just all of Sitka.”

Then that data is received by the National Weather Service in Juneau. Hydrologist Aaron Jacobs says they’re combining that information with soil moisture data that the team began collecting in 2019 with sensors installed on Gavan Hill, Mt. Verstovia, and Harbor Mountain. 

“With this increased knowledge base we’re going to have a lot better understanding of what conditions are needed for increased risk of debris flows,” he says. “Then our forecasters can look at these rain gauges and soil moisture sensors to see if they’re exceeding these thresholds. And if they’re exceeding any of these thresholds, then we would put out a statement or a warning.”

Once this network is completely set up, it will be the highest density of rain gauges in the State. Anyone in Sitka can access the data. 

Watch a video tutorial on how to access Sitka’s rainfall data

And it’s definitely going to be useful in the classroom. One of the tipping buckets will be monitored by Matthew Hunter’s physics students at Mt. Edgecumbe High School. 

“I used to teach private pilot ground school, and there’s a lot of weather science in that, because you need to know where clouds form, where you can expect turbulence and stuff like that as a pilot,” says Hunter. “So I brought some of that in my physics class- it will be interesting to see what sort of predictions students have about what areas of town might get more rain than others, and then look at the data and see if those carry through or not, and then try to figure out why that might be.”

And he’s planning on using the data in his algebra classes too. 

“It’s a real world example of statistics,” he says, “That could be fun to work with real world stuff instead of just what the textbook has, which, frankly, can be quite boring.”

Back at Sitka High, Golden comes to the third location she’s considering. She shows Siebert a lone pole, sticking out of the ground. It looks like an old rain gauge, covered in green skuzz. 

“This would probably be an easy place that we could either use that post and take that wood thing and stuff off of it, you’d already have a platform for it.”

“This would be perfect,” Siebert says, noting the open skies. 

Golden and Siebert have to consider a lot of factors when setting one up, including the probability that teenage curiosity could affect the data collection

“Do you think they’ll touch it?” Siebert asks Golden.
“I don’t know,” Golden laughs.

While high schoolers may be tricky to predict sometimes, researchers hope that this new system will make forecasting landslides a little easier.

Golden and Siebert (left) scout tipping bucket locations behind Sitka High School. Siebert says the project is funded by the National Science Foundation Smart and Connected Communities program in partnership with the RAND Corporation, University of Oregon, Sitka Tribe of Alaska, University of Southern California, and Alaska Division of Geological and Geophysical Survey, as well as the National Weather Service, US Forest Service, and US Geological Survey. (KCAW/Rose)