Hydro-sediment controls on fish habitat and movement in sediment-laden rivers: An ecohydraulic review with perspectives from the yellow river

Alluvial rivers with extreme sediment loads are frontiers in ecohydraulic research where conventional habitat models, based on static indices of suitability and water-centred physics, fail to reflect physiological and behavioural realities of aquatic life. This review synthesizes recent progress in mechanistic modelling incorporating hydrodynamics, sediment transport, and fish movement. Using the sediment-laden Yellow River as a representative system, the review identifies a transition from descriptive habitat suitability approaches to dynamic, process-based frameworks that consider not only hydrodynamic variables but also sediment stress as a primary ecological variable. Key developments include time-integrated Severity of Ill Effect index, bioenergetic constraints on aerobic scope, and behaviourally explicit individual-based models that represent fish as adaptive agents rather than passive sensors. These approaches demonstrate that suspended sediment alters fluid rheology, increases metabolic costs, and shapes functional connectivity, overlooked in traditional assessments. Case studies show engineered sediment pulses can make biologically impassable habitats within hydraulically continuous channels. Comparative analysis with the Amazon and Mekong suggests that ecological effects depend not only on sediment magnitude but also on the timing, predictability, and synchrony of sediment pulses with biological cycles. The review identifies priorities, such as behavioural processes in hyper-concentrated rivers, integration of multi-species interactions, and development of a scalable ecohydraulic modelling framework, needed for sustainable river management.