South Korea warns residents of flash floods 1 hour in advance

The system was introduced by researchers at the Korea Institute of Civil Engineering and Technology (KICT) last week. The flood control office has begun testing the system in Seoul and plans to expand it nationwide next year.

Once the system detects a flash flood risk, it will issue a warning through various channels such as emergency broadcasts, mobile apps, sirens, social media, and text messages, explained Hwang Seok Hwan, the research team leader.

In the new system, yellow labels mean floodwaters up to an adult's ankles, while orange means knee-high water and red corresponds to one meter of water, or waist-high, where it would be difficult to open a car door. (Photo: KITC)

These alerts are aimed at authorities, emergency responders, and the public so they can take appropriate action. With early warning, people can take precautions to protect their property, prepare emergency kits, and plan for evacuation.

Flash floods are among the deadliest natural disasters, killing more than 5,000 people each year, according to the World Meteorological Organization. They occur when heavy rains are concentrated in small areas, causing water levels to rise suddenly. The force of the rushing water can sweep away vehicles, causing casualties. In mountainous areas, they can also cause landslides, submerging and destroying homes.

When sudden flooding occurs, the Seoul Metropolitan Government advises residents to evacuate to higher ground and avoid traveling or driving into flooded areas. In August 2022, record rainfall flooded homes, roads, and subway stations across the country, causing flash floods that killed at least nine people and damaged about 2,800 homes. In low-lying areas such as Gangnam and mountainous areas, water rose and flowed much faster than other areas with the same amount of rain, according to the KICT expert team.

Flash floods are likely to become more frequent as global warming leads to more evaporation, which in turn creates more moisture in the atmosphere and causes intense rainfall. Meanwhile, climate change is changing rainfall patterns, leading to more intense and frequent rainfall in certain areas. Therefore, accurate prediction is a challenge and is crucial for early warning.

The KICT team has developed a real-time monitoring system for flood forecasting based on rainfall radar data from the Ministry of Environment and records of flood damage. The system sets thresholds for rainfall intensity, river water level and soil moisture, triggering alerts when thresholds are exceeded and flood risk increases.

During a four-year pilot run starting in 2019, the team said the flash flood forecasting system was effective in predicting major floods across the country an hour in advance. It predicted flash floods during 31 heavy rain events with a 90% success rate in 2019.

(According to Korea Times)

High, steep terrain becomes the 'flooding center' of Ho Chi Minh City . In Thu Duc City, Go Vap District has many roads that are high and steep but are often flooded.

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