Local authorities said 21 reports of damage — flooded roads, washed-out earth — were received after heavy rain in the Busan area. No casualties were reported.

Over the same period, heavy rain warnings covered Tainan, Kaohsiung and Pingtung in southern Taiwan. From late summer into early autumn, stationary fronts and tropical lows overlap, and large amounts of rain often fall in short bursts.

Where cities flood

Urban flooding repeats in the same places: low-lying underpasses, intersections with a history of standing water, and points where drainage pipes narrow. Intense rain over a short interval exceeds drainage capacity and water pools on the road.

Underground spaces are the sharpest risk. In semi-basement homes, underground parking and basement arcades, inflow outpaces drainage once water starts entering. At knee height, water pressure can hold a door shut.

What to check now

At home and in shops, clear leaves and litter from drain covers in advance and confirm that backflow valves on basement drains work. For driving, plan routes that avoid underpasses with a flooding history.

Alerts come by emergency text from the interior ministry and local governments, usually in Korean only. A practical arrangement for Chinese-heritage households is to keep a translation app's notifications on as well, or to designate one family member to check them.