With the development of society and economy and the acceleration of urbanization, the urbanization area and the underlying conditions of urban areas have changed greatly. In the case of the same amount of rainfall, because the impervious area is added, the runoff coefficient is increased, and the output is also increased accordingly.
The flood peak flow increases, and the peak time is earlier, which not only brings a great burden to downstream flood prevention and drainage, but also may result in poor drainage in some areas and water accumulation, which brings great inconvenience to people's lives.
In addition, precious rainwater resources are underutilized because rainwater is discharged. Therefore, many cities have adopted rainwater utilization measures, such as building cisterns, laying permeable bricks, and adopting recessed oasis.