Rapid increase of urban impervious surface, resulting from unplanned urban sprawl, leads to the frequent occurrence of urban flood disasters caused by abnormal precipitation in flood season. In this work, a coupled urban rain flood model and normal pipe network model is employed to simulate the city inundation and pipe network hydrodynamics under different local land use types. The results shows that the peak surface inundation and pipe network outlet flow after transformation were 4.36%–42.43% and 0.01%–1.34% higher than those before transformation for P ≤ 20, and its corresponding values reached 1.24%–5.59% and 27.26%–35.21% for P > 20. The change in land use types in local areas significantly impacted inundation of the whole surface under normal rainfall (P < 20), which was also verified by the water recession coefficient. In addition, land use transformation slightly affected urban inundation for P ≥ 100, which indicates that low-impact development facilities were almost ineffective in addressing inundation under extreme rainfall. A significant impact on the pipe network discharge was observed under the high rainfall return period (P ≥ 20). The recession coefficient obtained via coupled model simulations can be effectively applied in the urban flood recession process.

城市无规划扩张导致城市不透水面快速增加，导致汛期降水异常引起的城市洪涝灾害频发。本文采用耦合城市雨洪模型和正常管网模型，模拟了不同地方土地利用类型下的城市洪水和管网水动力。结果表明，P≤20时，改造后的地表浸水和管网出口流量峰值分别比改造前高4.36%~42.43%和0.01%~1.34%，对应值分别达到1.24%~5.59%和27.26%。 P > 20时为–35.21%。正常降雨下局部地区土地利用类型的变化对整个地表的淹没影响显着（P < 20），水衰退系数也验证了这一点。此外，P ≥ 100 时，土地利用转型对城市淹没影响较小，这表明低影响开发设施在解决极端降雨下的淹没问题几乎无效。在高降雨重现期（P≥20）下观察到对管网流量的显着影响。通过耦合模型模拟得到的衰退系数可以有效地应用于城市洪水衰退过程。