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 surveywas applied to derive the high-resolution Digital Surface Model (DSM) of the bed topography, usedfor the flow-bed interactions analysis, in a large amplitude meandering laboratory flume. Theanalysis has been conducted with the aid of detailed data of three-dimensional flow field previouslycollected using the acoustic Doppler velocity profiler DOP2000. The applied surveying procedurehas allowed the evaluation of the DSM with a resolution of ±0.5 mm. The detailed DSM has beencompared with peculiar maps describing the flow velocity pattern (downstream and the crossstreamflows) and the shear velocity distribution along the meandering flume. The comparison hashighlighted that high quality topographic data are of crucial importance to evaluate the crosscirculationeffect on the redistribution of the velocity and boundary shear stress and, thereby, onthe meandering channel evolution.