Responses of urban flood processes to local land use using a high-resolution numeric model

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.