Numerical simulation for the effects of waves and grain size on deltaic processes and morphologies

Abstract

Currently, the sedimentation process concerning the formation of the morphological changes of deltas under the action of waves has received little attention. Two numerical simulations were carried out in this study to explore the sedimentary morphological changes of deltas under wave action. In the first experiment, the morphological characteristics of river-dominated deltas and wave-dominated deltas were compared. Results showed that a wave-dominated delta was more likely to produce slender and stable rivers relative to a river-dominated delta. In the second experiment, the morphologies of wave-dominated deltas with sediments of different grain sizes were compared. Results indicated that delta morphology was not significantly correlated with the median grain size (φ50) of the sediment, and the average grain size of the coarser sediments (φ25) was an important factor affecting delta morphology. Moreover, a delta with a larger φ 25 value of the input sediment, a smaller topset gradient, and a smaller number of active river channels had a more arcuate shape. The results showed that the hydrodynamic numerical simulation method has the ability to reveal the evolution of deltas under the action of waves. The final simulation results were consistent with the actual delta data.