According to the Ministry of Housing and Urban-Rural Development of the People's Republic of China, investigations on more than 350 cities across the country have ceased. In the three years from 2008 to 2010, more than 60% of cities have experienced flooding. Waterlogging during heavy rains has become a common problem in many cities. The main manifestations are: increased urban flood risk; severe rainwater runoff pollution; severe loss of rainwater resources; and damage to the ecological environment.
At present, we are at the peak of urbanization. The original ponds and wetlands are becoming less and less, and the ground surface is "hardened"-all streets are covered with concrete pavements and cannot seep naturally. The city's parks and green spaces are far from enough. It caused 90% of the rainwater to enter the drainage system, which made it embarrassed. Once the city encountered a heavy rain attack, a large amount of rainwater was nowhere to be discharged. Therefore, the road became a river and the square became It became a lake and the sea, and traffic became paralyzed.
In addition, hard roads can absorb, store, and reflect the heat of the sun, which increases the air temperature, increases the city's summer heat, and increases the urban heat island effect. Therefore, compared with traditional hard roads, the improvement of permeable roads is more necessary.