River sediment supply (Qs) and longshore sediment transport (LST) are recognized as two paramount controls on river delta morphodynamics and stratigraphy. We employed the Delft3D model to simulate the evolution of deltas from fluvial to wave-dominated conditions, revealing the interplay between river- and wave-driven sediment quantities. Wave-influenced deltas may show alternating accumulation and retreat patterns driven by avulsions and wave-induced sediment diffusion, posing coastal management challenges. Deltas with higher wave energy evolve under a fine balance between river supply and intense wave-mediated sediment redistribution and are highly vulnerable under conditions of sediment reduction. Reducing Qs by ∼40%–70%, common in modern dammed rivers, can rapidly shift bypass from ∼0 to 1 (no bypass to complete bypass). This leads to accelerated diffusion and potential sediment loss in modern deltas. The study highlights the importance of accurately computing sediment quantities in real-world deltas for improved management, especially under increasing anthropogenic and climatic pressures.

中文翻译：

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受波浪影响的三角洲形态动力学、由河流相对大小和波浪驱动的沉积物输送控制的长期沉积物旁路和捕获


河流沉积物供应 （Qs） 和长岸沉积物输送 （LST） 被认为是河流三角洲形态动力学和地层学的两个主要控制因素。我们采用 Delft3D 模型来模拟三角洲从河流到波浪主导条件的演变，揭示了河流和波浪驱动的沉积物量之间的相互作用。受波浪影响的三角洲可能表现出由撕脱和波浪诱导的沉积物扩散驱动的交替堆积和后退模式，对沿海管理构成挑战。具有较高波浪能的三角洲在河流供应和强烈的波浪介导的沉积物再分配之间的良好平衡下演变，并且在沉积物减少的条件下非常脆弱。在现代堰塞河流中，将 Qs 减少 ∼40%–70% 很常见，可以迅速将旁路从 ∼0 变为 1（没有旁路以完成旁路）。这导致现代三角洲的加速扩散和潜在的沉积物损失。该研究强调了准确计算真实世界三角洲中沉积物数量对于改善管理的重要性，尤其是在人为和气候压力不断增加的情况下。