Estimating suspended matter concentrations from SPOT data and from field measurements in the Rhône river plume

The quantification of surface suspended particulate matter in the Rhone river plume is investigated using SPOT imagery. The method of satellite data calibration from sea-truth data is described. Sea surface particle concentrations are measured through filtration of surface water samples, and multiwavelength reflectance profiles are collected by a 256-channel field radiometer from 400 to 1100 nm. Regression analysis are performed on in situ reflectance data versus Suspended Sediment Concentration (SSC) data. The derived empirical laws are then applied to the image data. The field campaign and the SPOT image shots were carried out during autumn 1994. Two cases are presented. One case concerns a quasi-normal river discharge and the other case concerns a flood situation. SSC maps resulting from the method of inversion are presented and discussed.