Autocyclic Secondary Channels Stabilize Deltaic Islands Undergoing Relative Sea Level Rise
Autocyclic Secondary Channels Stabilize Deltaic Islands Undergoing Relative Sea Level Rise
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DOI：
10.1029/2022gl098885
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发表时间：
2022-08
影响因子：
5.2
通讯作者：
G. Salter;M. Lamb
中科院分区：
文献类型：
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作者：
G. Salter;M. Lamb
了解三角洲岛屿的大小和稳定性对于预测三角洲如何应对海平面上升至关重要。漫滩沉积模型产生了一个指数衰减的沉积剖面，似乎与岛屿的稳定性不相容，这需要均匀的沉积平衡海平面上升。然而，次级河道提供了一种机制，可将沉积物更深地输送到岛屿内部，从而可能稳定岛屿。使用一维形态动力学模型，我们发现，自生次级通道允许岛屿或岛屿的一部分，以保持一个稳定的配置文件动态通过循环的通道切割和加积。然而，当岛太大时，次级通道生长成为稳定的主要通道，从而平分岛，导致更小，更稳定的岛与通道网络的连接。而不是被动溺水，我们的研究结果表明，三角洲岛屿可以响应海平面上升，通过形态动力学的反馈，以提高岛屿增生。
Understanding what sets the size and stability of deltaic islands is critical for predicting how deltas will respond to sea level rise. Models of overbank sedimentation produce an exponentially decaying sedimentation profile, seemingly incompatible with island stability, which requires uniform sedimentation balancing sea level rise. However, secondary channels provide a mechanism for delivering sediment deeper into island interiors, potentially stabilizing islands. Using a 1D morphodynamic model, we found that autogenic secondary channels allow islands or parts of islands to maintain a stable profile dynamically through cycles of channel incision and aggradation. However, when islands are too large, secondary channels grow to become stable, primary channels, thereby bisecting the island, resulting in smaller, stable islands with more connectivity to the channel network. Rather than passively drowning, our results indicate that deltaic islands can respond to sea level rise through morphodynamic feedbacks that act to enhance island accretion.