Scaling up bedload monitoring: a passive acoustic approach for large river systems

Quantifying bedload transport at the catchment scale of large rivers remains a critical challenge in river management and sediment budget assessment. Traditional direct sampling methods are logistically demanding and provide limited spatial-temporal coverage. This study demonstrates that passive acoustic monitoring using hydrophones can reliably quantify bedload fluxes across entire river catchments. Applied to the Loire River system (France), passive acoustic measurements were conducted at seven stations from 2018 to 2025, establishing bedload rating curves for discharge conditions ranging from low flow to two-year return floods. Monte Carlo sensitivity analysis demonstrates that stratified sampling with as few as four measurements across the discharge range produces reliable rating curves (