Landslide warning sensor installation scheduled for Sitka

(KTUU)

ANCHORAGE, Alaska (KTUU) - Starting next month, sensors that can help detect landslides will be installed in Sitka.

A dozen soil moisture sensors will be buried about three feet deep in locations on ridges above the Southeast Town and transmit data in real time.

"The reason we want to understand how wet the soils are is because when a storm is foretasted to be approaching Sitka and it has the capability of delivering a certain amount of rainfall, we want to know whether the soil is already saturated and if that amount of rainfall might be likely to trigger a landslide or not," said Josh Roering, an earth sciences professor at the University of Oregon who is working on the project.

In addition to Roering's colleauges at the University of Oregon, several other partners including the United States Forest Service and the University of Southern California are involved in different parts of the process. The project is spearheaded by the RAND corporation, and funded by the National Science Foundation.

Water is the key driver in the landslides common in Southeast Alaska, including a deadly 2015 slide that killed three men in Sitka.

Roering says once installed, it will take several months to calibrate the sensors to ensure they are accurate.

However, simply determining when and where a landslide is most likely to happen is not the biggest challenge the project faces. Determining how and when to best alerts residents in at-risk areas is an equally important part of the project.

"Not the entire town of Sitka is in these debris flows, so it needs to be geographically distinct. So one thing is how do you deliver warning information to a limited number of households," Roering said. "And then the next is how often do you want the public, the people in these areas to deal with was we call a false alarm when the conditions are right for a landslide, but for whatever reason, one doesn't happen. We want to minimize the inconvenience and the disruptions in people's lives, but we also want to minimize the amount of times when a landslide does happen and we fail to give an alarm."

Roering says the system should be up and running in about a year and that more sensors will eventually be installed.

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