Atoll reef islands primarily consist of unconsolidated sediment, and their ocean‐facing shorelines are maintained by sediment produced and transported across their reefs. Changes in incident waves can alter cross‐shore sediment exchange and, thus, affect the sediment budget and morphology of atoll reef islands. Here we investigate the influence of sea level rise and projected wave climate change on wave characteristics and cross‐shore sediment transport across an atoll reef at Kwajalein Island, Republic of the Marshall Islands. Using a phase‐resolving model, we quantify the influence on sediment transport of quantities not well captured by wave‐averaged models, namely, wave asymmetry and skewness and flow acceleration. Model results suggest that for current reef geometry, sea level, and wave climate, potential bedload transport is directed onshore, decreases from the fore reef to the beach, and is sensitive to the influence of flow acceleration. We find that a projected 12% decrease in annual wave energy by 2100 CE has negligible influence on reef flat hydrodynamics. However, 0.5–2.0 m of sea level rise increases wave heights, skewness, and shear stress on the reef flat and decreases wave skewness and shear stress on the fore reef. These hydrodynamic changes decrease potential sediment inputs onshore from the fore reef where coral production is greatest but increase potential cross‐reef sediment transport from the outer reef flat to the beach. Assuming sediment production on the fore reef remains constant or decreases due to increasing ocean temperatures and acidification, these processes have the potential to decrease net sediment delivery to atoll islands, causing erosion.

中文翻译：

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海平面上升将推动前礁和礁滩上不同的沉积物运输方式，可能导致环礁岛侵蚀

环礁岛主要由未固结的沉积物组成，其海面海岸线由沉积物产生并在整个礁石中运输。入射波的变化会改变跨海沉积物交换，从而影响环礁岛的沉积物预算和形态。在这里，我们研究了海平面上升和预计的波涛气候变化对马绍尔群岛共和国夸贾林岛上的一个珊瑚礁的波涛特征和跨岸沉积物运输的影响。使用一个相位解析模型，我们可以量化波浪平均模型不能很好地捕获的数量，即波浪的不对称性和偏斜度以及水流加速度，对泥沙输运的影响。模型结果表明，对于当前的礁石几何形状，海平面和海浪气候，潜在的床荷运输方向是陆上，从前礁到海滩下降，并且对水流加速度的影响敏感。我们发现，到2100年，预计年波浪能减少12％，对礁滩水动力的影响可以忽略不计。但是，海平面上升0.5-2.0 m会增加礁石平面上的波高，偏度和切应力，并降低前礁的波偏度和切应力。这些水动力变化减少了珊瑚产量最大的前礁在岸上的潜在沉积物输入，但增加了从外礁滩到海滩的潜在跨礁沉积物运输。假设由于海水温度升高和酸化作用，前礁上的沉积物产量保持恒定或减少，这些过程可能会减少向环礁岛的净沉积物输送，从而造成侵蚀。