Hydrodynamic coupling between ground, pipe, river and sea: critical review and future directions

ABSTRACT A comprehensive review is conducted on the hydrodynamic process of urban flooding, ranging from interactions between ground runoff, pipe flow, river flow and sea. Coupled models representing these interactions are critical for effective urban flood management. This review addresses the research objectives, governing equations, simulation methods, case studies and performance evaluation of various coupled models. The literature analysis reveals that most coupled models are not fully developed, except for surface runoff and pipe flow coupling. These methods present distinct advantages and limitations in computational efficiency, experimental complexity and practical applicability. In case studies, approximately half of the applications quantify the error metrics of water level or flooding range and perform well over tens or hundreds of square kilometers. In addition, current challenges, including coupled model complexity, monitoring data scarcity and high-quality experimental gap, were discussed, which demonstrates the limitations of refined flooding simulation. Correspondingly, three recommended directions for the future development of hydrodynamic coupled models are proposed.