Flow Field Measurements around Distributary Channels on Wax Lake Delta, Louisiana, USA

Flow patterns are one of the key elements of delta morphodynamics. However, limited field measurements from delta fronts restricts the understanding of this environment. Data was collected from the subaqueous portion of Gadwall pass on Wax Lake Delta, Louisiana, over a three month flood cycle (March 21 to June 30, 2017) using tilt meters to quantitatively measure the flow field around distributary channels. The data showed flow patterns that were significantly affected by floods, tides, and whether the site was in a channel, a shallow interdistributary bay, or the delta front. Flow within the channels had the largest mean velocity (277 mm/s) and highest variation in speed (s = 160 mm/s), but the least variation in bearing over tidal cycles (s = 33.1°). Measurements in interdistributary bays had high mean speed (223 mm/s), with lower variation in speed but higher variation in bearing over tidal cycles (s = 82 mm/s and s = 46.3°, respectively). The delta front had the lowest mean speed (194 mm/s). Compared to interdistributary bays, the delta front had a lower variation in speed (s = 79 mm/s) and a higher variation in bearing (s = 49.7°). These observations provide new insights into flow and sediment transport patterns at the tips of prograding distributary channels.