It is widely recognized that waves inhibit river mouth progradation and reduce the avulsion timescale of deltaic channels. Nevertheless, those effects may not apply to downdrift‐deflected channels. In this study, we developed a coupled model to explore the effects of wave climate asymmetry and alongshore sediment bypassing on shoreline‐channel morphodynamics. The shoreline position and channel trajectory are simulated using a “shoreline” module which drives the evolution of the river profile in a “channel” module by updating the position of river mouth boundary, whereas the channel module provides the sediment load to river mouth for the “shoreline” module. The numerical results show that regional alongshore sediment transport driven by an asymmetric wave climate can enhance the progradation of deltaic channels if sediment bypassing of the river mouth is limited, which is different from the common assumption that waves inhibit delta progradation. As such, waves can have a trade‐off effect on river mouth progradation that can further influence riverbed aggradation and channel avulsion. This trade‐off effect of waves is dictated by the net alongshore sediment transport, sediment bypassing at the river mouth, and wave diffusivity. Based on the numerical results, we further propose a dimensionless parameter that includes fluvial and alongshore sediment supply relative to wave diffusivity to predict the progradation and aggradation rates and avulsion timescale of deltaic channels. The improved understanding of progradation, aggradation, and avulsion timescale of deltaic channels has important implications for engineering and predicting deltaic wetland creation, particularly under changing water and sediment input to deltaic systems.

中文翻译：

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三角洲海岸线通道形态动力学上的波浪控制：耦合模型的见解

众所周知，波浪会抑制河口的扩张并减少三角洲河道的侵蚀时间尺度。但是，这些影响可能不适用于向下漂移的通道。在这项研究中，我们开发了一个耦合模型来探讨波浪气候不对称和沿岸沉积物绕过对海岸线-通道形态动力学的影响。使用“海岸线”模块模拟海岸线位置和河道轨迹，该模块通过更新河口边界的位置来驱动“河道”模块中河流剖面的演变，而河道模块为河口提供泥沙负荷“海岸线”模块。数值结果表明，如果限制了河口的泥沙绕行，那么由非对称波浪气候驱动的区域性近岸泥沙运移可以增强三角洲河道的发育，这与普遍认为波浪会抑制三角洲增长的假设不同。因此，海浪可能会对河口水质的发展产生折衷影响，进而影响河床水质的沉积和河道的侵蚀。波浪的这种折衷效应是由沿岸的净沉积物输送，沿河口的沉积物绕过以及波浪的扩散性决定的。根据数值结果，我们进一步提出了一个无量纲的参数，该参数包括相对于波扩散率的河流和近岸沉积物供应量，以预测三角洲河道的进水和积水速率以及侵蚀时间尺度。