Experimental study and numerical simulation of stormwater retention performance of intensive green roofs

The rapid development of urbanization， has a negatire effect on the urban ecological environment in certain areas. Consequently， the construction of sustainable ecological cities has become a critical issue. A combined approach of on-site experiments and numerical simulations was adopted. Firstly， simulated rainfall experiments were conducted to monitor and analyze key indicators of stormwater retention performance. Secondly， based on the actual engineering design parameters of a residential community in Nanning， SWMM software was used for simulation to explore the hydrological effects and drainage network efficiency under various conditions， including different rainfall recurrence periods， green roof coverage rates， and green roof distribution patterns. The optimal construction method for intensive green roofs to enhance stormwater retention in the study area was identified. The results indicated that intensive green roof coverage significantly improved the stormwater retention performance of the community， and the performance improvement tended to plateau when the coverage rate exceeded 80%. Uniformly distributed green roofs performed the best in reducing total runoff， whereas those distributed at intervals achieved optimal results in regulating peak runoff and alleviating pipeline overloads within the residential area. This study can help evaluate the stormwater retention performance of intensive green roofs in subtropical regions to optimize urban rainwater management strategies.