Seoul City Invests 3.5 Trillion to Greatly Strengthen 'Flood Safety Net'... Raises 'Rainfall Management Target' for the First Time in 10 Years

'Development of a Denser Flood Safety Network Strategy' to Prepare for Climate Disasters
Enhancing Response by Raising Disaster Prevention Performance Target to 100mm per Hour
Real-Time Evacuation Alerts for Flooding in Semi-Basements and Expansion of Care Officials for Vulnerable Groups

[Asia Economy Reporter Lim Cheol-young] To respond to the climate crisis that has become a reality, the Seoul Metropolitan Government is drastically shifting its flood control system to focus on ‘climate disasters.’ As the intensity and frequency of unpredictable localized heavy rains increase every year, causing greater uncertainty in flood management, the city plans to build a more sophisticated flood safety network to protect citizens' lives by enhancing flood prevention goals and capabilities in line with the changed conditions.

On the 6th, Seoul announced that it will implement the ‘More Detailed Flood Safety Network Promotion Strategy (2022?2032),’ which includes installing ‘deep rainwater drainage tunnels’ at seven locations such as Gangnam Station to handle heavy rain exceeding 100mm per hour. As an advanced flood control measure responding to the climate crisis era, the city will invest 3.5 trillion KRW over ten years to implement 17 measures across five sectors. The five sectors are ▲ Resetting rainfall handling targets ▲ Expanding region-customized disaster prevention facilities ▲ Establishing data- and prediction-based systems to secure evacuation golden time ▲ Strengthening safety for flood-vulnerable households such as semi-basement residents ▲ Expanding public and private safety facilities.

Localized heavy rains, which are difficult to predict, are increasing in both intensity and frequency every year. According to the Seoul Metropolitan Weather Administration, heavy rain warnings due to localized heavy rains increased more than 30 times from 3 cases in 2021 to 91 cases this year. During recent heavy rains, rainfall conditions changed rapidly, with rain cloud bands forming within 15 to 30 minutes, showing patterns completely different from the past.

[Image source=Yonhap News]

First, Seoul will raise the current ‘disaster prevention performance target (rainfall handling target)’ from 95mm per hour to 100mm per hour. Since the Gangnam Station area is a basin-type terrain vulnerable to flooding, it will be designated as a ‘priority management area’ and the target will be further raised to 110mm per hour. The ‘disaster prevention performance target’ will be flexibly applied considering the hydrological and hydraulic characteristics of each region, socioeconomic factors, and the capacity of urban rivers. The ‘priority management area’ will start with Gangnam Station and gradually expand through technical analysis and social consensus procedures.

In line with the raised ‘disaster prevention performance target,’ flood prevention facilities will be precisely installed and expanded by region. By 2032, 1.5 trillion KRW will be invested to install a total of 18.9 km of ‘deep rainwater drainage facilities’ in six flood-vulnerable areas including the Gangnam Station area. In flood-prone areas, 2 trillion KRW will be invested to significantly improve flood prevention infrastructure such as expanding rainwater pumping stations, constructing new rainwater storage tanks, maintaining sewage pipes, and widening river cross-sections.

Soldiers from the 35th Special Mission Battalion of the Army's Capital Defense Command are providing civilian support on the 10th by organizing flooded households and belongings in the residential area near Sinsa Traditional Market in Gwanak-gu, Seoul, which was damaged by heavy rain. Photo by Kim Hyun-min kimhyun81@

Regarding the deep rainwater drainage tunnels, installations will be prioritized by 2027 at Gangnam Station, Dorimcheon, and Gwanghwamun. In the second phase, the areas around Sadang Station, Yongsan, and Gildong will be completed by 2032. With an investment of 1.2 trillion KRW, among the 420 sub-districts in Seoul requiring maintenance, 46 flood-vulnerable areas such as Myeonmok and Jangwi (totaling 598 km) will be prioritized for pipe diameter expansion and maintenance by 2032. Subsequently, the capacity of 18 rainwater pumping stations will be increased. Five stations including Yangjae will be upgraded by 2026, five including Seorae by 2028, and eight including Simwon and Munbae by 2030 in sequence.

Water circulation facilities capable of storing rainwater will be expanded more than twice the current scale to reach 480,000 cubic meters per hour by 2040. To achieve this goal, existing gray infrastructure roads will be reorganized into blue-green infrastructure water circulation roads, and existing rainwater inlets will be replaced with infiltration-type rainwater inlets. Additionally, installation costs for rainwater management facilities such as rainwater gardens, which combine rainwater runoff reduction and garden functions, will be supported. The city will pilot-install ‘urban green dams’ utilizing idle spaces such as traffic islands and green areas within the city.

[Image source=Yonhap News]

Following criticism that delayed evacuation and response due to lack of prior knowledge of flooding during recent heavy rains exacerbated damages, a response system to secure citizens’ evacuation golden time will be established.

Seoul will pilot a ‘smart warning system’ in May next year that measures flooding conditions on roads and other areas using Internet of Things (IoT) sensors and automatically disseminates real-time alerts via text messages and other means. For the first time nationwide, an ‘inundation warning and alert system’ will be introduced not only for landslides and river flooding but also for flood-prone residential areas such as semi-basement houses, underground parking lots, and general roads. For roads, real-time flood information will be provided through navigation apps such as T map and KakaoMap. By the end of the year, the ‘disaster map’ will be updated to reflect the raised disaster prevention performance targets and changed terrain conditions to enhance response capabilities.

Moreover, Seoul plans to build a more intelligent ‘AI-based integrated flood control system’ by 2030 that automatically analyzes and predicts related data and disseminates information in real time and simultaneously using artificial intelligence (AI) technology. The ‘AI-based integrated flood control system’ will be constructed through the ‘Flood Prediction Information System’ that predicts flood levels based on rainfall, a ‘Big Data System’ that analyzes various measurements from IoT sensors, surveillance cameras (CCTV), social network service (SNS) information, and verifies flood information, and the ‘Flood Control System Advancement Project’ that strengthens control and communication functions.

Flood safety measures for vulnerable households such as semi-basement residents will also be strengthened. For semi-basement households where disaster-vulnerable individuals such as people with disabilities and elderly living alone who have difficulty evacuating in emergencies reside, a ‘care public officer’ will be assigned one-on-one to provide tailored support from pre-inspection of flood prevention facilities to evacuation information dissemination and recovery. Regardless of housing location or flood history, any semi-basement resident can apply to have flood prevention facilities such as water barriers installed free of charge, and support will also be extended to small-scale commercial establishments.

Public and private safety facilities will also be expanded. By the end of the year, ‘fall prevention facilities’ will be installed at 10,000 manholes, and 19,000 water pumps, which saw explosive demand during flooding, will be distributed to community centers and other locations before next year’s rainy season. Additionally, flood barriers will be installed at all subway station entrances by May next year, and legislation will be pursued to mandate the installation of flood barriers such as water barriers in apartment underground parking lots.

Han Yoo-seok, Director of the Water Circulation Safety Bureau of Seoul, said, “Preventing flood damage requires significant budget and time, but citizen safety is non-negotiable, so we will prepare meticulously and proceed without setbacks.” He added, “For flood prevention measures to be fully established, active participation from citizens is essential, so we ask for the public’s keen interest and cooperation.”

This content was produced with the assistance of AI translation services.