This data is collected to assess the role of hydrograph timescale relative to dune migration on the preservation of cross sets in the stratigraphic record. The data presented here are of dune evolution under steady-state conditions, as well as three hydrographs of the same magnitude but varying timescales.
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Lower Bound on Preserved Flood Duration in Fluvial Bedform Stratigraphy (experimental dataset)
Robert C. Mahon, Vamsi Ganti, Madeline M. Kelley, Debsmita Das, Victoria Sanchez, Giancarlo Portocarrero, and Mayson Fredricks
This data is collected to assess the role of hydrograph timescale relative to dune migration on the preservation of cross sets in the stratigraphic record. The data presented here are of dune evolution under steady-state conditions, as well as three hydrographs of the same magnitude but varying timescales.
Methodology:
We collected data from four experiments tracking bedform evolution in a 22-m-long, 0.56-m-wide, 0.9-m-deep flume at the University of New Orleans Dynamics of Sedimentation laboratory. We conducted an equilibrium experiment (discharge value 0.027 m3/s) and three flood experiments, which were characterized by a symmetrical flood wave. In all flood experiments, the flood magnitude increased linearly from the baseline condition (0.027 m3/s) and peaked at the same flood magnitude (0.044 m3/s), which was held for 5 minutes, and then the flood magnitude decreased linearly to the same baseline condition. We only varied flood durations across these experiments, and we label the four experiments as the “equilibrium,” “fast,” “intermediate” and “slow” flood experiments. The fast, intermediate, and slow flood experiments had a total flood duration of 25 min (Tf, fast = 12.5 min), 69 min (Tf, mid = 34.5 min), and 191 min (Tf, slow = 85.5 min), respectively. In all experiments, we recirculated water and sediment, and held the flow depth constant at 0.152 m as the experimental apparatus allowed a more precise control of uniform flow under varying discharge without stage increase.
We measured topography using a 3D laser scanning system along an approximately 5.5-m-long test section, located 5.3 m downstream of the inlet, with scans repeated approximately every 165 seconds. We analyzed bed topography for the 2D centerline profile at 1 mm horizontal resolution. For each experiment, we selected the timespan to contain the same duration of pre-flood and post-flood baseflow conditions.
Specific laboratory notes from each experiment are appended as .txt files.