Measurements of spatio-temporal fluvial channel bed evolution in an array of yawed porous vanes at the Saint Anthony Falls Laboratory (SAFL) main channel

Abstract

Controlling lateral sediment flux and bed surface elevation distributions is important engineering solutions for sustainable river management. However, quantification of the lateral sediment flux has posed great challenges for river engineers for decades due to difficulties in measuring high resolution 2D spatio-temporal bed surface evolution data, \eta(x,y,t), when lateral sediment flux control is imposed by hydraulic structures. Here, \eta is bed surface elevation. Dimensions x and y are stream- and span-wise directions, and t is time. We conducted two sets of open channel experiments, in which \eta(x,y,t) was monitored using the state-of-the-art laser scanning data acquisition system. The first experiment was carried out without hydraulic structures, namely baseline case. The second experiment was conducted under the same hydraulic condition with an array of yawed porous vanes that were installed at the one-half of the channel width, imposing asymmetric lateral sediment flux. By comparing results from these two sets of experiments, the effects of an array of yawed porous vanes on the lateral sediment flux were quantified. We found that an array of porous yawed vanes can effectively direct sediment flux in the lateral direction by 9-18% of the averaged streamwise sediment flux under the current array configurations and hydraulic conditions.