High-Resolution Suspended Sediment Concentration Dynamics along River Corridors

Suspended sediment concentration (SSC) plays a critical role in riverine systems, influencing ecosystem health, water quality, and sediment transport and deposition. While reach-scale hydraulics determine the available shear stress during a flood and thus sediment flux, the type and quantity of suspended sediment within a river are derived from watershed processes and near-channel properties. A river’s visual color can be monitored from remote sensed images, where the color is a combination of SSC, organic matter, and other particulate pollutants carried by the river. Here we pair high-resolution records of SSC and remotely sensed imagery to investigate the spatial and temporal patterns within river color along river corridors. Preliminary geospatial analysis reveals that mean SSC weakly increases with drainage area, raising questions about the mechanisms driving SSC changes downstream. We utilize remotely sensed imagery to explore how river color correlated with SSC records changes in relation to discharge, tributary spacing and drainage area contribution, watershed attributes, to determine key mixing distances and whether increases in SSC (changes in color) occur primarily at the node scale, such as tributaries, or as a result of gradual downstream fluxes. We utilize these high-resolution temporal and spatial data to inform probabilistic descriptions of SSC and sediment flux along the river corridor where calibration data may be limited. Understanding the dynamics of water color and its relation to SSC changes within a river corridor represents a critical launching pad for leveraging remotely sensed images to predict sediment flux, monitor concentration patterns, and inform strategies for watershed management.