A comprehensive review of watershed flood simulation model

Flooding is a major threat that presents a significant risk to human survival and development worldwide. Regarding flood risk management, flood modeling enables understanding, assessing, and forecasting flood conditions and their impact. This paper gives an overview of prevailing flood simulation models given their potentials and limitations for reflecting pluvial floods in watershed settings. The existing models are categorized into hydrologic, hydrodynamic, and coupled hydrologic-hydrodynamic models. The coupled hydrologic-hydrodynamic model can be further classified into full, external, and internal coupling models. The definitions, advantages, and limitations of each coupling model are discussed. It is found that the existing coupling types cannot accurately reflect the flood evolution processes. A dynamic bidirectional coupled hydrologic-hydrodynamic model is then detailed, where the watershed is spatially divided into inundation and non-inundation regions. These two regions are connected by a coupling moving interface. Only 2D hydrodynamic models are applied to the local inundation regions to ensure numerical accuracy, whereas the fully distributed hydrologic model is applied to non-inundation regions to improve computational efficiency. Future investigation should focus on the development of a dynamic bidirectional coupling procedure that can accurately represent the complex physical interactions between upstream rainfall-runoff and the local inundation process. This paper would help flood managers and potential users undertake effective flood modeling tasks, balancing their needs, model complexity, and requirements of input data and time.