Physical experiments on fill-terrace formation and sediment-signal disruption

This data collection contains topographic scans, overhead photographs and experiment documentation of the experiments published in Tofelde, S., Savi, S., Wickert, A., Bufe, A., Schildgen, T., 2019. Alluvial channel response to environmental perturbations: Fill-terrace formation and sediment-signal disruption. ESurf.

The experiments were run in November and December 2015 at Saint Anthony Falls Laboratory, Minneapolis, USA. The experimental setup consisted of a wooden box with dimensions of 4 m x 2.5 m x 0.4 m that was filled with quartz sand with a mean grain size of 144 ?m. At the inlet, water discharge (Qw) and sediment supply (Qs,in) could be regulated separately. At the 20 cm wide outlet sediment discharge (Qs,out) could be measured and the base level could be controlled. The water was dyed blue to better distinguish wet from dry areas.

This dataset contains seven experiments. In each experiment, we varied either upstream water discharge (Qw), upstream sediment supply (Qs,in) or downstream base level. For each experiment, we provide an experiment log sheet, the topographic laser scans, overhead photographs and time-lapse movies. Details on each dataset are given below.

1. Experiment documentation
The metadata for each experiment is summarized in an excel spreadsheet. For each experiment, we provide the input parameters (Qs,in and Qw), the bed elevation at the inlet and outlet and the according bed slope (assuming a straight channel), sediment discharge at the outlet (Qs,out) and the start and stop times to perform the topographic laser scans.

2. Topographic scans
Laser scans were performed every 30 minutes (exception base-level fall experiment, 10 to 15 min) using a custom built laser scanner. The scans were acquired in five parallel, overlapping swaths that were merged afterwards (merged scans provided here). The experiments had to be interrupted to acquire the scans (absolute times given in the excel spreadsheet). The horizontal resolution is 1 mm and the scans cover 1700 by 3400 pixels, cutting 300 pixels at the upstream and downstream end, respectively. Scans are numbered with the numbers given in the excel spreadsheet.

3. Overhead photographs
Overhead photographs were acquired every 20 seconds using a fish-eye lens. The distorted photos were ortho-rectified in Adobe Photoshop using an inbuilt lens correction and were resampled at a 1 mm horizontal resolution (corrected photos provided here). Photos are named by date and absolute time and are provided in jpg format (e.g. Img2015-12-05 11.45.49
copy.jpg). Each folder contains two additional text files containing the image names and the according experimental runtime in seconds. Photos taken without running water, or when the dye was not working, were removed. No photos were taken for the Ctrl_1 experiment due to an error in the camera installation.

4. Time-lapse movies
In addition, time lapse videos of each run were generated by stitching the overhead photos together. Movies were generated from the unprocessed photos and are thus for display only, not for analyses.