Intrinsic vs. extrinsic controls on experimental shallow lacustrine delta channel evolution: sediment load and lake level

Abstract

This study used a physical model to investigate the internal dynamics and external effects of upstream incoming sediment concentration and downstream lake level on channel morphology evolution in a laboratory-scale shallow lacustrine delta under the background of Poyang Lake Delta (China). The results show that the channels exhibit straight, braided, and no-channel patterns. Sediment deposition in the downstream channel causes rising topography, backwater pressure, and deposition lobes, leading to periodic channel switching. Higher incoming sediment concentration and lake level can result in a shorter evolution period, larger swing angle, and higher swing point position for the main channel in delta. Furthermore, the delta topography is more likely to change from a distributary to a radial pattern with higher incoming sediment concentration, and this factor appears to play a more important role than the downstream lake level in fundamentally influencing the deltaic channel patterns.