Landslides may be predicted in the future with a new landslide model that combines all the factors contributing to the catastrophic events — including severity and duration of rainfall, as well as soil and geological qualities of the land — the National Science Council said yesterday.
Whereas traditional models calculate landslide probabilities using either rainfall data or geological data of a region, the new model combines rainfall data with geology and geomorphology data, Kainan University’s Chang Kang-tsung (張康聰) said.
Researchers from National Tsinghua University and Feng Chia University began developing the system three years ago with funding from the Ministry of Economic Affairs.
Chang said the team has developed a prototype that has proven effective in trials on the Feng Chia University campus and other outdoor locations.
After developing the model in 2004, Chang tested it in 2005 with Typhoon Haitang and found that it showed 87 percent accuracy, compared with 66 percent accuracy for rainfall-based models, he said.
“Taiwan’s mountainous areas are very suitable for landslide research, as the island is on a plate collision zone, boasts steep slopes and has very short rivers,” Chang said.
The triggers for most landslides in Taiwan are torrential rain and earthquakes, Chang said, adding that the former is mostly caused by typhoons.
“As most foreign rainfall-based landslide models employ mid-latitude cyclonic precipitation as opposed to typhoon-related precipitation, which not only is more intense but also brings more rainfall, these models may not be suitable for predicting landslide probabilities in Taiwan,” Chang said.
Because the equipment and the installation cost of the new system are both cheaper than the cost of setting up a traditional precipitation collection station, Chang said the new system could be deployed in the 1,500 areas around Taiwan vulnerable to mudslides.
“By so doing, we can collect more comprehensive rainfall data to help local meteorologists make more precise weather forecasts and mudslide alerts,” he said.
That would prevent hundreds of people being buried alive in mudslides in remote mountainous villages as occurred earlier this month in Kaohsiung County after Typhoon Morakot dumped a staggering amount of rainfall in the area.
However, although Chang said his model can potentially offer governmental agencies more accuracy when it comes to issuing landslide alerts in the future, several key factors would need to be implemented for the model to work.
As data plugged into the demonstrative example is an estimation based on rainfall statistics taken from the International Panel on Climate Change (IPCC) databank, the government will probably not adopt Chang’s model at the moment because “there are too many uncertainties … The IPCC number conservatively underestimates typhoon-brought rainfalls.”
To make his model more useful, “a more accurate and comprehensive set of geological data [some of them currently classified for national security reasons], as well as a better set of rainfall data [collected locally] would be needed,” Chang said.
ADDITIONAL REPORTING BY CNA
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