Structural design and simulation analysis of large permeable parking lot in sponge city based on SWMM

To improve the safety of urban underground parking lot and promote the construction of sponge city, a large parking lot structure of sponge city was designed based on rainstorm water management model (SWMM). A new permeable material paving method was designed for a parking lot in Handan City, and a low impact development (LID) parking lot model was constructed based on the SWMM. The simulation results showed that the runoff reduction effect of the permeable parking lot was significant. There was a delay of 3.36 minutes during the 30 minutes of rainfall period. During the 60 minutes rainfall period, there was a delay of 8.5 minutes. The lowest runoff reduction rate was 44% for a 100-year return period. The highest runoff reduction rate was 100% for 60 minutes rainfall duration and a 1-year return period. The lowest runoff reduction rate was 50% for a 100-year return period. The LID permeable parking lot had better runoff control effect, with a total runoff volume of 233 m3, a reduction rate of 83.5%, a peak flow rate of 0.152 m3/s, and a reduction rate of 73.4%. The LID parking lot model developed based on the SWMM has better drainage and water storage performance, making it more suitable for the construction of large permeable parking lots in sponge cities. The permeable parking lot structure studied effectively reduces the time of runoff effect of parking lot, improves the safety of underground parking lot during rainstorm, and promotes the construction and development of sponge city.