Laboratory data of bed topography, grain size, water depth and flow velocity along alternate bars

Experiments performed in a 24-meter-long flume with fixed straight and fixed banks, with erodible bed composed by a mixture of sediments. In each experiment, water discharge Q is kept fixed. Sediment supply is adjusted to maintain overall equilibrium with the initial channel slope S=1%. All data refer to the final equilibrium state. Two experimental series: MW40: channel width W=40 cm, mean grain size 1.22 mm MW60: channel width W=60 cm, mean grain size 1.29 mm Five types of products (geotiff format, spatial resolution 0.5x0.5 mm): Ortophotos (RGB), obtained from Structure-from-Motion photogrammetry Elevation model (DEM) [m], obtained from Structure-from-Motion photogrammetry Grain size maps (d50) [mm], obtained from image analysis Water depth maps (depth) [m], obtained from 2-D shallow water simulations Shear stress maps (tau) [Pa], obtained from 2-D shallow water simulations Water velocity field (velocity) [m/s], obtained from 2-D shallow water simulations File "Grain_size_samples.csv" contains data on the 24 sediment samples used to calibrate the method for automated grain size extraction from images. For details see: Redolfi, M., Ragno, N., Welber, M., & Bertoldi, W. (2025). Grain size sorting and steady bars formation in straight channels - Part 1. Laboratory experiments. Journal of Geophysical Research: Earth Surface (submitted). The laboratory experiments were supported by the project GLORI, funded by the Autonomous Province of Bolzano-Bozen. We thank Francesco Boeri, Michele Portogallo and the staff of the Hydraulic Laboratory for their help in the execution of the experiments.