Estimating Net Sediment Fluxes in Tidal Systems Using Sporadic Data Sets: Implications for Using Remote Sensing to Assess Saltmarsh Resilience

Abstract Sediment budgets are diagnostic of saltmarsh resilience, yet quantifying net sediment fluxes remains constrained by limited, asynchronous observations of suspended sediment concentration (SSC) and water flux. Using high‐frequency observations from 15 U.S. saltmarsh stations, we combine phase folding and Monte Carlo simulations to assess whether sporadic sampling can reliably resolve net sediment exchange. We show that asynchronous SSC and water‐flux measurements spanning >8 full tidal cycles robustly identify sediment sources and sinks. High‐resolution optical satellite archives (Sentinel‐2) typically capture >30 tidal cycles in most saltmarshes, yielding 5%–41% uncertainty in net flux magnitude across systems. This accuracy is sufficient to distinguish saltmarshes functioning as sediment sources from those acting as sinks at regional to global scales, though local calibration could improve accuracy. Integrating optical remote sensing with emerging water‐flux technologies can therefore enable scalable assessments of tidal saltmarsh sediment budgets, providing a pathway for evaluating coastal resilience under accelerating sea‐level rise.