141.5 mm in one hour
On the night of 8 August 2022, an automatic weather station (AWS) in Sindaebang-dong, Dongjak-gu, recorded 141.5 mm of rain in one hour, the highest one-hour total observed in Seoul.
At the same time, other parts of Seoul received far less. In the hardest-hit districts, including Gangnam, Dongjak and Gwanak, roads, underground spaces and semi-basement homes flooded, with loss of life.
Three things that day showed
Rain does not fall evenly
Rainfall varied sharply within a few kilometres in the same city. A city average cannot pick out the places at risk.
Risk is where water collects
Underpasses, semi-basement homes and low-lying roads are hit first and hardest by short, intense rain.
Alerts must reach action
The time it takes for a warning to reach someone who cannot evacuate alone, and for help to arrive, decides the outcome.
What changed afterwards
Seoul later introduced a flood advisory and warning system based on rainfall and road water levels. It also runs a companion partner programme that links vulnerable residents, such as those in semi-basement homes, with nearby neighbours and officials in advance to help them evacuate.
For these systems to work, the rainfall that triggers them has to be observed in time, at the place that is at risk.
Sources
- 2022년 8월 중부지방 집중호우 관측 자료 — 기상청, 2022
- 서울시 침수 예·경보제, 동행파트너 운영 안내 — 서울특별시, 2023
