275-2 Linking Remotely Sensed River Reflectance to Suspended Sediment Concentration in the Upper Colorado River Basin

Abstract:

Suspended sediment concentration (SSC) plays a critical role in river systems, influencing ecosystem health, water quality, and reservoir capacity. Measuring SSC within a reach remains challenging and time-consuming making basin-wide measurements infeasible.  However, a river’s reflectance (i.e., color) can be monitored from remotely sensed images, where the reflectance is a combination of SSC, organic matter, and other particulate pollutants carried by the river. Here we focus on pairing individual sites within the Colorado and Green River basins with high-resolution SSC records (+10 years of 15-minute data) with remotely sensed imagery (Landsat and Sentinel) to determine which spectral variables, bands, and indices best predict SSC. Critically, we explore a collapse of the remotely sensed sediment relationships across sites by accounting for channel hydraulics, river discharge, near-channel attributes, and grain size. This single-site modeling approach enables robust sediment concentration estimation from reflectance data, from which patterns of changing sediment dynamics can be directly observed basin-wide. The high-resolution informed basin-wide snapshot represents a key step toward leveraging remote sensing for sediment flux prediction, concentration monitoring, and watershed management. 

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