Landslide risks are growing each year as localized torrential downpours concentrated over narrow areas become more frequent. Although the monsoon season is entering its final stretch, the possibility of heavy rain remains, prompting calls for stronger measures such as enhanced evacuation systems.
According to the Korea Forest Service on the 23rd, the average annual number of landslides more than quadrupled, from 521 during 2015-2019 to 2,232 during 2020-2024. Last year alone saw 2,637 landslides, exceeding the five-year average. In particular, a series of large landslides in Sancheong, South Gyeongsang Province, and Gapyeong, Gyeonggi Province, left 17 people dead—the highest toll in the past decade.
Localized torrential rain is cited as a major cause of worsening landslide damage. It is generally known that landslide risk rises sharply when hourly rainfall exceeds 30 mm or cumulative rainfall exceeds 200 mm.
The problem is that as the global average temperature rises, localized torrential downpours are occurring more frequently and intensely in Korea than before. When sea surface temperatures rise and atmospheric water vapor supply increases, atmospheric instability intensifies—creating conditions prone to heavy rain. According to the Korea Meteorological Administration, the frequency of downpours exceeding 50 mm per hour over the past five years averaged 31 times annually, about three times the 10 times recorded in the 1970s.
This year's monsoon season has also seen repeated heavy rainfall. On the 17th, Suseong-gu in Daegu received 89 mm of rain in one hour, prompting the first-ever disaster-level heavy rain emergency alert since its introduction. That day, the Seoul metropolitan area and Gangwon also saw heavy rain of 20-30 mm per hour. The Korea Meteorological Administration forecast that the monsoon would end nationwide between the 26th and 27th of this month but urged people not to let their guard down against torrential rain. Indeed, last year, after the monsoon ended, Deokjeokdo in Incheon received 149.2 mm per hour in August and Gunsan in North Jeolla Province received 152.2 mm per hour in September. Moreover, Korea has topographical features that make it vulnerable to landslides, with many steep slopes and low soil cohesion.
Experts agree that rainfall patterns should be analyzed to periodically update landslide risk prediction maps and that resident evacuations should be conducted preemptively. Jung Su-jong, a professor at Seoul National University's Graduate School of Environmental Studies, said, "'Compound disasters,' in which torrential rain compounds soil already weakened in cohesion by heat waves, are increasing every year," adding, "Above all, it is important to advance systems that use artificial intelligence (AI) and other technologies to monitor soil moisture content and ground movement in real time."
