00:00 Rainy Season: The Dangers of Underground Spaces
01:25 Experiencing the Dangers of Underground Flooding
04:42 How to Escape via Stairs
05:43 What If Water Rises in an Underground Parking Lot?

1. Rainy Season: The Dangers of Underground Spaces
The rainy season is in full swing. During periods of heavy rainfall like we are seeing recently, underground spaces are the most dangerous places to be. This includes semi-basement homes, underground parking lots, and underpasses. These areas are particularly hazardous because they can flood in an instant when it rains heavily. You may recall that four years ago, in 2022, when Typhoon Hinnamnor struck the Korean Peninsula, a river overflowed and submerged an apartment complex's underground parking lot in Pohang, North Gyeongsang Province. Seven residents lost their lives because they could not escape; they had gone down to move their cars after hearing an announcement that the parking lot was flooding. That same summer, in Sillim-dong, Gwanak-gu, Seoul, two sisters in their 40s and a teenage daughter died after failing to escape their flooded semi-basement home. According to government data on deaths and disappearances caused by storms and floods over the past 10 years, 37 out of 199 victims—about 20 percent—were lost due to the flooding of underground spaces. The reason these spaces are so lethal during heavy rain is that the path for water entry is often the same as the path for evacuation, making it extremely difficult to push through the current to safety.

[Gong Ha-seong / Professor of Fire and Disaster Prevention, Woosuk University: You have to evacuate through the same path where the water is entering, and the water is rushing in with great force.]

2. Experiencing the Dangers of Underground Flooding
To understand just how dangerous and difficult it is to escape a flooded underground space, I tried it myself. I visited the Boramae Safety Experience Center, operated by the Seoul Fire and Disaster Headquarters, where various risks associated with storms and floods can be simulated. I specifically tested how to evacuate from a flooded underground area, experiencing situations where water levels reached 30cm, 50cm, and 70cm. When this report aired on the 8 o'clock news, some comments suggested that it shouldn't be that hard to escape or that I wasn't trying hard enough. Before I actually tried it, I also thought, "I'm strong, maybe I could get out." But after the experience, I realized how arrogant I had been.

[The water is at my knees, about 50cm deep. No matter how hard I push, the door won't open.]

I also watched other citizens try it. An adult woman could not open the door, and when a sturdy adult man tried, the door only rattled without opening. Although it wasn't shown in the news report, I also tried it when the water reached about 70cm—up to my thighs. At that point, no matter how much force I applied, the door wouldn't budge, as if someone were pushing against it from the other side. The National Disaster Management Research Institute has conducted experiments on this. When the water level was 30cm, both men and women could escape. However, when the water reached 40cm—about calf-height—men could still escape, but women could not. Once the water reached 50cm—knee-height—it was impossible for both men and women to escape. A researcher at the National Disaster Management Research Institute explained that water at a depth of 50cm exerts a force similar to having a 110kg boulder pressing against the door.

[Kim Hak-soo / Team Leader, Urban Flood Experiment Team, National Disaster Management Research Institute: Even with just 50cm of water, it has an effect similar to having a 110kg boulder outside the door. The door becomes so heavy that it cannot be opened. At 40cm, in terms of water pressure, it's equivalent to about 70kg for a standard fire door.]

Because it becomes impossible to open a door and escape once water reaches knee height, the best course of action is to evacuate immediately at the first sign of rising water or if water begins to back up from a drain. Some may wonder about the proper posture for opening a door. If you need to push the door open, you should lower your body and press your shoulder firmly against the door while pushing with all your might. If you need to pull the door open, grab the handle with both hands and pull with full force while in a squatting position.

[Choi Yeon-woo / Operation Team Leader, Boramae Safety Experience Center: Stand a step away from the handle, place your shoulder against the center of the door, stand at a slight angle, and put all your strength into it.]

3. How to Escape via Stairs
Escaping through the door is not the end. In underground spaces, you often have to climb stairs to get out. When ascending stairs where muddy water is pouring down, you must hold onto the handrail firmly with both hands. You might think you should hold onto rails on both sides, but in a situation with a powerful torrent, spreading your arms wide can cause you to lose your balance and fall backward, so you should hold onto the handrail on one side with both hands. Once you have a firm grip, move by sliding your feet along the floor rather than lifting them, as if you were skating, to stay safe.

[Choi Yeon-woo / Operation Team Leader, Boramae Safety Experience Center: Since you often can't see the stairs due to sediment, lifting your feet too much can cause you to fall backward due to the water pressure, so you should keep your feet as close to the floor as possible.]

Also, it is better to be barefoot than to wear boots that fill with water and make it hard to lift your feet, or dress shoes that can cause you to slip.

4. What If Water Rises in an Underground Parking Lot?
If water starts rising in an underground parking lot or underpass, it is best to abandon your vehicle. Even if water only reaches half the height of the tires, the water pressure can trap you inside. If you are late to evacuate and become trapped in your car, try to open or break the window; if you are in an SUV, open the trunk to create an escape route. Some people might think they can quickly drive out to the surface before the parking lot floods, but this is extremely dangerous. A car can float due to buoyancy once the water reaches about two-thirds of its height. Once that happens, even a slight current can easily sweep the car away, leaving you helpless. Therefore, it is very dangerous to assume you can drive through even what looks like shallow water. While we have covered evacuation methods, the most important thing is prevention. Experts emphasize installing sandbags or flood barriers in advance and checking drains before heavy rain arrives. I hope everyone stays safe and sound this summer.

Reported by Dong Eunyeong | Produced by Shin Hee-sook | Video by Choi Dae-woong | Video Editing by Kim Hye-ju | Graphics by Yook Do-hyun | Produced by SBS Digital News