In principle, it is possible to determine SPM based on satellite images for a large part of the Scheldt estuary. Nevertheless, a number of challenges need to be tackled in the Zeeschelde and Boven-Zeeschelde in particular. There, the river is only 1 or a few pixels wide in places (Sentinel 2 spatial resolution: 10m-20m). Furthermore, the tidal action continuously ensures resuspension and settling. The SPM concentration at the surface therefore exhibits strong temporal variability, which complicates the interpretation of a snapshot based on satellite image. Drones offer a possible solution to both problems, but have their own difficulties (flight planning, weather conditions). In this study, methods are developed to determine SPM in the estuary from satellite and drone images, using continuous data for calibration.