**Abstract Text**
The method of doing experiments affects the general performance of bendway weirs and rock vanes in a livebed, alluvial-channel bend.  For livebed conditions on sand beds, maximum dune heights are comparable to the mean crest elevations of these rock structures, thereby potentially reducing their effectiveness. The authors conducted experiments with a curved flume fitted with a sand bed and used two methods for doing the experiments: one wrong, and one correct.
The wrong method is termed here the before-and-after method. The bathymetry along the bend was formed before placing a series of bendway weirs or rock vanes (each series comprised six rock-structures). After documenting the water-surface flow field by means of Large-Scale Particle Velocimetry, the flume was drained, and its bed bathymetry recorded by means of LiDAR. Afterwards, a series of six bendway weirs or rock vanes was placed and the experiment repeated.  The water-surface flow field and the bed bathymetry were again documented.  This method was done for three flows.
The correct method is termed here the hydrograph method. This method entailed first forming the bed’s bathymetry. A frequent, representative (say annual peak), livebed flow was used for this purpose. Then the series of rock structures was placed, a lesser flow used, the surface flow field measured, the flow drained, and bed bathymetry recorded. The flow then was increased (rock structures remaining) to replicate four flows in the rising limb of a flood wave passing through the bend. This method revealed how bendway weirs or rock vanes perform and fail in livebed flow conditions.



**Abstract Text**
The method of doing experiments affects the general performance of bendway weirs and rock vanes in a livebed, alluvial-channel bend.  For livebed conditions on sand beds, maximum dune heights are comparable to the mean crest elevations of these rock structures, thereby potentially reducing their effectiveness. The authors conducted experiments with a curved flume fitted with a sand bed and used two methods for doing the experiments: one wrong, and one correct.
The wrong method is termed here the _before-and-after method_. The bathymetry along the bend was formed before placing a series of bendway weirs or rock vanes (each series comprised six rock-structures). After documenting the water-surface flow field by means of Large-Scale Particle Velocimetry, the flume was drained, and its bed bathymetry recorded by means of LiDAR. Afterwards, a series of six bendway weirs or rock vanes was placed and the experiment repeated.  The water-surface flow field and the bed bathymetry were again documented.  This method was done for three flows.
The correct method is termed here the _hydrograph method_. This method entailed first forming the bed’s bathymetry. A frequent, representative (say annual peak), livebed flow was used for this purpose. Then the series of rock structures was placed, a lesser flow used, the surface flow field measured, the flow drained, and bed bathymetry recorded. The flow then was increased (rock structures remaining) to replicate four flows in the rising limb of a flood wave passing through the bend. This method revealed how bendway weirs or rock vanes perform and fail in livebed flow conditions.



A Correct Method for Experiments on the Livebed Performance of Bendway Weirs and Rock Vanes (Room 312, Wednesday June 28th, 8:30am-10:00am)

Engineers, researchers, and climate scientists share developments and innovative practices in the water engineering industry. The Technical Committee for Hydraulics Measurements and Experimental Methods (TCHMEM) of EWRI has organized the HMEM conference six times since 1994, when the first HMEM conference was held in Buffalo, NY. Since then, successful conferences were held in Estes Park, Colorado (2002), Lake Placid, New York (2007), Snowbird, Utah (2012), and Durham, New Hampshire (2017).