Seoul City will prepare countermeasures to cope with extreme weather, including heavy rain, ahead of summer. The city plans to introduce technology that can detect water levels in real-time, even in narrow alleys, using radar sensors mounted with water level monitoring equipment. Additionally, it aims to increase the number of 'rainwater containers' that can hold rainwater for ponds and lakes from 7 to 12 this year.
Oh Se-hoon, the mayor of Seoul, inspected the measures for disaster preparedness in a report meeting for the '2025 flood and disaster safety plan' held at the city hall on the 12th.
Seoul City plans to promote measures this year to prepare for heavy rains, including ▲intensive management of low-lying and disaster-prone areas ▲detection of flood risks in alleys ▲securing rainwater containers ▲strengthening collaboration with the Korea Meteorological Administration, police, military, and fire services.
First, the city will focus on managing low-lying areas vulnerable to flooding or isolation when it rains, such as semi-basement dwellings, underground passages, and riverside walking paths.
The city will utilize rain gauges and road-level monitoring devices installed throughout Seoul to collect real-time water level information for low-lying flood-prone areas. Based on this data, the city plans to issue flood risk alerts. For example, if rainfall exceeds 20 mm in 15 minutes, 55 mm within an hour, or if road flooding reaches a depth of 15 cm, any one of these will trigger a flood warning. Flood alerts will be issued after assessing the risk level through on-site confirmation and closed-circuit (CC) TV.
When flood alerts are issued, each autonomous district will send disaster text messages to residents informing them of the flood warnings.
This year, Seoul City plans to pilot the installation of 'semi-basement flood warning facilities' in alleyways of 15 areas, including Gwanak, Dongjak, and Yeongdeungpo districts, where semi-basement dwellings are densely located. The radar sensors with water level monitoring equipment will detect real-time water levels to monitor flooding even in narrow alleys where flood surveillance is difficult.
A Seoul official noted, “The newly introduced RAY radar sensor can be installed in narrow spaces like streetlights and utility poles, enabling the extension of the flood monitoring network down to narrow alleys.” Previously, existing water level monitoring equipment, such as road gauges, required larger spaces and were mainly installed along main roads.
Additionally, when flood forecasts are issued, designated 'companion partners' will visit households in semi-basement areas, especially those with disabled, elderly, or child residents, to check for risks and assist with evacuation. This year, there will be 2,887 companion partners helping 1,130 vulnerable households.
Moreover, 98 underground passages that are at risk of flooding will also be designated for intensive management. If the road surface is flooded by more than 10 cm, these areas will be immediately controlled. For riverside walking paths, preventive control measures and automatic alert systems will be activated from the preliminary warning stage.
For areas vulnerable to landslides, Seoul plans to issue landslide alerts based on prediction information from the Korea Forest Service (provided 2 to 48 hours in advance) after conducting situational judgment meetings.
The city will also add five more 'rainwater containers (natural retention basins)' this year to prevent the concentration of stormwater in rivers. Rainwater containers are designed to hold rainwater in park ponds and lakes to suppress the rapid rise in water levels caused by drainage into urban rivers. Currently, there are seven operating facilities, including the Cheonggye Reservoir at Seoul Grand Park, and with the addition of five more, there will be a total of 12. The city estimates that this will allow for the storage of up to 757,000 tons of rainwater.
Seoul City also announced the establishment of a dedicated 'hotline' for real-time communication with the Korea Meteorological Administration to respond quickly to heavy rains. This is a dedicated line connecting the Korea Meteorological Administration's weather center with the disaster safety control center of Seoul City. It enables the exchange of real-time and precise weather information, including updates on forecast changes.
In addition, Seoul City will continue to operate a partnership with police, military, and fire services this year. At the end of this month, a joint 'operation training for the disaster safety headquarters for flood preparedness' will be conducted with relevant agencies to assess disaster response capabilities.
The city will also continue to expand large-scale disaster prevention facilities in key flood-prone areas. Within this year, construction will begin on a 'deep underground stormwater drainage tunnel' that will store and discharge rainwater during heavy rains in areas such as Gangnam Station, Dorimcheon, and Gwanghwamun. The installation of nine new or upgraded rainwater pumping stations and three rainwater reservoirs will be gradually implemented by 2030.
Mayor Oh Se-hoon remarked, “As the climate crisis becomes a global phenomenon threatening our daily lives, disaster preparedness must become more thorough.” He added, “We will execute flood disaster measures in partnership with related agencies through meticulous pre-preparation, including system and facility checks.”