Extreme rainfall in Geoje, South Gyeongsang Province, exceeded 100 mm per hour during the early morning hours this week [1].
The event highlights the danger of rainfall intensity, where the speed of accumulation creates immediate flood risks regardless of the total daily volume.
Local authorities issued four emergency disaster-alert messages for a "disaster-level heavy rain" situation as the downpour continued [1]. The intensity of the storm caused rapid water accumulation, a phenomenon that often leads to sudden urban flooding.
Comparing rainfall rates helps illustrate the severity of the Geoje event. According to YTN reporter Choi Ah-young, rainfall of 15 mm per hour is enough to make windshield wipers run continuously and cause water to pool on roads [2]. When rates reach 30 mm per hour, umbrellas typically become ineffective [2].
The rate experienced in Geoje was more than triple that threshold. Choi said there is a significant difference between 50 mm of rain falling over a full day and the same amount falling within a single hour [2].
Such extreme events are becoming a point of concern for national safety. Last year, 15 locations across South Korea experienced rainfall exceeding 100 mm per hour [2].
While Geoje faced these extreme conditions, other regions saw different forecasts. A YTN weather bulletin said Gyeongbuk was expected to see strong rain with maximums of 50 mm per hour through late afternoon [1].
“Rainfall in Geoje exceeded 100 mm per hour during the early morning hours.”
The Geoje event underscores a shift toward high-intensity precipitation patterns. When rainfall exceeds 100 mm per hour, traditional drainage infrastructure is often overwhelmed instantly, transforming manageable weather into a disaster-level event. This pattern suggests that municipal planning must prioritize peak-flow capacity over average rainfall totals to mitigate urban flooding.
