Posted on July 21, 2025
As rivers burst their banks and flood alerts rang out across Korea this week, Daejeon remained eerily dry — and it may have city hall’s excavators to thank.
While much of the country was inundated by torrential rains, the central city — crisscrossed by three major rivers — saw little damage, a striking outcome that some attribute to a monthslong river dredging project completed just weeks before the storms hit.
According to the Daejeon city government, the accumulated rainfall from Wednesday to 6 p.m. on Thursday reached 188.6 millimeters (7.4 inches) in Guseong-dong. At one point, 47 millimeters fell in just an hour early Thursday.
“In the past, that much rain would have submerged riverside walkways and forced the closure of bridges like Mannyeon, Boksu and Wonchon,” a city official said. “But this time, the water drained smoothly, and the riverbanks remained intact.”
From December 2024 to June of this year, Daejeon dredged its three main rivers and carried out flood prevention work, investing 17.2 billion won ($12.36 million). The dredging removed 680,000 tons of sediment, lowering riverbeds by between 50 centimeters (1 foot, 7 inches) and 150 centimeters along a total of 17.9 kilometers (11 miles).
For decades, river dredging had been stalled in Daejeon due to environmental opposition. As a result, sediment buildup raised riverbeds, making the area prone to flooding. A flood warning was regularly issued in the region, and in July 2020, a massive inundation submerged parts of Jeongnim-dong. On July 10 last year, 122 millimeters of rain caused a levee to collapse in Yongchon-dong, flooding the area and damaging a bridge.
Seoul also saw no major flood damage despite heavy rainfall, a contrast to the city’s August 2022 disaster. This year, the Seoul Metropolitan Government implemented a range of measures, including intensive management of low-lying and high-risk areas, real-time monitoring of flood-prone alleys, improved retention systems in ponds and lakes and stronger coordination with the Korea Meteorological Administration, police, military and fire agencies.
One of the key new systems is Korea’s first underground flooding alert system, installed on a trial basis in 15 neighborhoods with high concentrations of semibasement homes, including Gwanak, Dongjak and Yeongdeungpo Districts. The system uses radar sensors to detect water levels in real time.
Seoul also designated 98 underpasses as high-priority areas and will shut them down immediately if water levels rise more than 10 centimeters.
In contrast, several rivers in South Chungcheong — including the Dangjin, Galsan and Dodang Streams — overflowed during the recent deluge. The Sapgyo Stream, a tributary of the Geum River, was placed under a flood warning, while multiple tributaries of the Yeongsan River in Gwangju prompted warnings or alerts for possible flooding. Omok Stream in Gyeongsan, a tributary of the Nakdong River, was also under a flood advisory. These rivers are not believed to have undergone the same level of intensive dredging over the winter as Daejeon’s three main rivers.
In North Chungcheong, the Miho River posed a flood risk as well. The river had already drawn criticism during the 2023 Osong underpass disaster due to insufficient dredging and flood prevention. Although Cheongju had planned dredging work, the project was delayed by environmental protests and budget constraints, and subsequent river maintenance has also been insufficient.
