Flow-bed interactions analysis and application of automatic close range digital photogrammetric survey in a laboratory flume

This paper reports on a laboratory study in which the automatic digital photogrammetric survey was applied to derive the high-resolution Digital Surface Model (DSM) of the bed topography, used for the flow-bed interactions analysis, in a large amplitude meandering laboratory flume. The analysis has been conducted with the aid of detailed data of three-dimensional flow field previously collected using the acoustic Doppler velocity profiler DOP2000. The applied surveying procedure has allowed the evaluation of the DSM with a resolution of ±0.5 mm. The detailed DSM has been compared with peculiar maps describing the flow velocity pattern (downstream and the crossstream flows) and the shear velocity distribution along the meandering flume. The comparison has highlighted that high quality topographic data are of crucial importance to evaluate the crosscirculation effect on the redistribution of the velocity and boundary shear stress and, thereby, on the meandering channel evolution.