Arctic delta channel dynamics and coastal deposition patterns are uniquely affected by ice and permafrost. Building on previous experiments that documented the individual effects of ice and permafrost, we conducted new numerical modeling experiments to examine the combined influences of ice thickness and permafrost erodibility. We quantified the effects of ice, permafrost, and their combination on channel migration, avulsion, and persistence; onshore and nearshore deposition; and large‐scale delta morphology. Both ice and permafrost limited channel mobility, enhanced overbank deposition, and roughened shorelines. Thick ice increased offshore channel incision and sediment delivery. Permafrost stabilized channels and focused deposition that led to enhanced channel levee development. The increased levee deposition limited widespread channel infilling leading to the preservation of abandoned channels. Levee growth was enhanced by overbank flooding due to ice‐driven changes in water surface elevations. This flooding led to more extensive levees on deltas with both ice and permafrost compared to deltas with only permafrost. Ice also preserved small channels, leading to size‐dependent channel persistence: the presence of ice in the channels reduced the fraction of time small channels remained active relative to larger channels. Resistant permafrost damped this effect, as smaller and more distal channels were active earlier in the flood on deltas with resistant permafrost likely due to the smaller number of channels on permafrost‐laden deltas. Finally, our results suggest that the loss of both ice and permafrost will increase channel mobility, decrease overbank flooding, increase shoreline progradation rates, and decrease offshore transport of riverine fluxes.

中文翻译：

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揭示冰和多年冻土对北极三角洲地貌动力学的综合影响

北极三角洲河道动力学和沿海沉积模式受冰和多年冻土的唯一影响。在记录冰和永久冻土的单独影响的先前实验的基础上，我们进行了新的数值模拟实验，以检验冰厚度和永久冻土易蚀性的综合影响。我们量化了冰，多年冻土及其组合对河道迁移，撕脱和持久性的影响；陆上和近岸沉积；和大规模三角洲形态。冰和永久冻土都限制了河道的流动性，增加了岸上沉积物，并使海岸线变粗糙。厚冰增加了海上通道的切口和沉积物的输送。多年冻土稳定了河道并集中了沉积物，从而增强了河道堤防的发展。堤防沉积物的增加限制了广泛的河道充填，导致保留了废弃的河道。由于冰驱动的水面高程的变化，堤岸泛滥促进了堤岸的生长。与仅具有永久冻土的三角洲相比，这种洪水导致在具有冰和永久冻土的三角洲上的堤防泛滥。冰还保留了小通道，从而导致了大小依存的通道持久性：通道中冰的存在减少了小通道相对于较大通道保持活动状态的时间比例。抵抗性多年冻土减弱了这种影响，因为洪水泛滥的三角洲较早时活动的河道越小越多，而抵抗性永久冻土可能是由于多年冻土承载的三角洲上的河道较少而造成的。最后，