Exposure of rescue pictures in Zhengzhou subway tunnel. How do rescuers help trapped people?

China has a vast territory, vast terrain and diverse terrain types. Especially in summer, some areas in China are prone to floods and flash floods. Debris flow and other disasters. Especially in the South China Plain, Jiangsu and Zhejiang provinces. Because the terrain is relatively flat, it is easy to get waterlogged, and because of the coast, it is particularly vulnerable to typhoons. Rainfall is formed by the influence of water vapor in the Pacific Ocean. If typhoons converge, it will increase rainfall and form a rainstorm disaster. In some mountainous areas, especially mudslides and landslides will be encountered. Because of the relatively high terrain in mountainous areas and the attack of heavy rain, some landslides and even mudslides will be caused. These are very fatal disasters for residents living in mountainous areas. In July 17, heavy rain broke out suddenly in Zhengzhou. From July 17 to July 20, the rainfall in these three days has been the annual rainfall in Henan Province. Overnight, Zhengzhou almost became a giant swimming pool. Because of the backlog, the accumulated water inside can't be discharged. Urban road water can reach a height of several meters, especially the impact of floods, and even achieve the purpose of washing away a person. Underground, it seriously affects the operation of subway, train and other rail transit, and even makes tourists who travel by subway trapped underground. The trapped passengers can't help themselves to escape, and there is no food and other supplies below. This is very dangerous. It is very difficult to work underground, because groundwater siltation cannot be ruled out, and it is difficult to find an outlet to discharge groundwater. A large number of rescuers are needed to carry sandbags and rescue them manually to get the trapped people out of danger. At the same time, it made up some food supplies for the masses in time, thanks to it. The timely command of the government and the timely dispatch of rescuers did not cause particularly great losses. Heavy rains in Zhengzhou are mostly caused by extreme weather and also affected by typhoons.