When the record-breaking heavy rain was reported on August 8th, the Gangnam area had been largely swamped. As heavy rain started pouring around when many people got off their work, hundreds of thousands of commuters, including people who do not live in Gangnam, battled for finding more safe routes to go back home during the heavy rainfall.

According to the Korea Meteorological Administration, a whopping of around 380 millimeters of rain fell in the Gangnam area, which had already been severely swamped twice by heavy rains in 2010 and 2011. In response to the floods in the past, the Seoul city government has renovated the drainage system within the area to withstand up to 85 millimeters of rain per hour. Despite all efforts to minimize the flood damage, the renovated system was not good enough to drain record-breaking heavy rain.

There are several reasons for the repetitive floods in the Gangnam area. First of all, the geological characteristics of the Gangnam area are the primary reason thereof. The Gangnam district is about 10 meters lower in altitude than its surrounding areas, and this makes it much easier for rainwater to accumulate than in its adjacent areas. In addition, the Gangnam area is highly developed with pavements and impermeable surfaces, and thus, the Seoul city government has improved infrastructure, such as underground flood tunnels, to overcome critical geological and environmental disadvantages of the Gangnam area’s vulnerability to heavy rain floods. Recently, the construction of a new underground Banpo flood tunnel was completed in June 2022 to withstand precipitation up to 95 millimeters per hour. The Seoul city government originally designed the maximum capacity of the Banpo flood tunnel as 95 millimeters per hour based on the average precipitation in recent 30 years. However, the city government should have considered that the occurrence of heavy rainfall of more than 150 millimeters per hour has been increasing since the 1990s. Recent heavy rainfall and flooding remind us of the old proverb: “Lock the stable door after the horse has bolted.”

황동원 강남포스트 학생기자  webmaster@ignnews.kr

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