Stream bed and water profile responses to in-channel restoration structures in a stream meander

Grade control and flow deflection structures are commonly installed in streams as stream restoration treatments. Few studies have pre- and post-treatment data to evaluate channel hydraulic gradients and morphology responses, both of which have implications on hyporheic exchange. We developed a scaled physical model of a stream meander---with and without cross-vane and J-hooks---and applied close-range photogrammetry techniques to obtain 3-D water and ground surface profiles with sub-millimeter accuracy. Results indicated that the cross-vane caused an average local head loss representing 16% of the total stream reach head loss. Backwater upstream of the cross-vane steepened the local water table profile by an additional 4.2%, and was the primary driver of statistically significant hydraulic gradient increases. Installation of the structures produced consistent spatial patterns of surface-water to groundwater gradients and bank and bed scours. Detailed reach-scale water and streambed surface profiles from our study can improve modeling of hyporheic exchange.