<p>Scour poses a critical threat to bridge safety, with a significant number of bridge failures attributed to scour-related damage. Despite the diversity of bridge scour monitoring methods, a significant gap remains in establishing a standardized classification system for essential indicators, including operating principles, sensor types, installation methods, resolution, and influencing factors, as well as a cohesive framework for evaluating performance indicators such as accuracy and applicability. This paper presents a comprehensive review of bridge scour monitoring methods based on operating principles of acoustic/electromagnetic wave reflection, electrical/magnetic field sensing, optical fiber sensing, heat conduction, and structural dynamics analysis. It explores the advancements in various scour monitoring techniques, including sonar, radar, time-domain reflectometry, piezoelectric thin-film, capacitive, smart rocks, fiber Bragg grating, thermal probes, and structural dynamics analysis. The focus is on essential indicators such as operating principles, realization algorithms, sensor innovations, and influencing factors. The relationships between essential and performance indicators are thoroughly established. The analysis evaluates the effectiveness of these methods alongside their key influencing factors, providing a robust framework for understanding and enhancing bridge scour monitoring practices.</p>