Sediment grain size is provided in a single spreadsheet (“BMF_GRAD_Grainsize.xlsx”) containing the main statistical parameters from the laser grain size analysis. The first sheet contains the ID code of the samples and their WGS842 Lat/Lon coordinates. The rest of the spreadsheets contain the results of the grain-size analysis of all the samples for each single field campaign. Due to the spatio-temporal variability of CLM morphodynamics, some sample records are discontinuous over time, due to water level, wave conditions or rock bed exposure.