A time series of aerial images of a dune field on a migrating free bar in the North Loup River, Nebraska, is used to generate a quantified dataset that allows analyses of crestline deformation, dune interaction type and spatial density, and impact of spurs. Measurement of dune parameters show that the dune field maintained a dynamic steady-state pattern, despite high rates of deformation, common interactions, and sediment bypassing. Mapped crestlines had a mean migration rate of 8 cm/min. The mean deformation rate, quantified using a partial Procrustes analysis, was 2 cm/min, indicating that along individual crestlines, local migration varied ± 25% from the bedform mean. Dune interactions caused the break-apart and recombination of crestline segments, thus limiting pattern variability caused by deformation. Although most of the 50 documented interactions are comparable to those observed in aeolian dune fields, defect-driven interactions are less common and interactions caused by migration of the convex-downstream nose of the dunes were observed, which has not been reported in aeolian dunes. The spatial density of interactions is consistent with that derived for aeolian crescentic-dune fields, in spite of differences in ambient fluid and dune size. Although spurs were ubiquitous, their presence did not have a quantifiable impact on deformation and interactions as compared to areas where spurs were absent, suggesting that these short-lived features affect instantaneous flux rates only.

中文翻译：

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水下沙丘场中的模式演化及其相互作用：美国内布拉斯加州北卢普河

内布拉斯加州北卢普河上一个自由移动的沙洲上的沙丘场的航拍图像用于生成量化数据集，该数据集可以分析c线变形，沙丘相互作用类型和空间密度以及马刺的影响。沙丘参数的测量表明，尽管变形率高，共同相互作用和绕过沉积物，但沙丘场仍保持动态稳态模式。映射的rest线的平均迁移速度为8厘米/分钟。使用部分Procrustes分析量化的平均变形速率为2 cm / min，这表明沿着各个顶线，局部偏移相对于床形平均值±25％。沙丘相互作用导致峰线段的断裂和重组，从而限制了变形引起的图案变化。尽管已记录的50种相互作用中的大多数都与风沙丘领域中观察到的相互作用具有可比性，但缺陷驱动的相互作用并不常见，并且观察到了由沙丘凸状下游鼻孔迁移引起的相互作用，这在风沙丘中尚未见报道。尽管周围流体和沙丘大小存在差异，但相互作用的空间密度与风沙新月形沙丘场的密度一致。尽管无处不在，但与不存在杂散的区域相比，它们的存在对变形和相互作用没有可量化的影响，这表明这些短暂的特征仅影响瞬时通量。缺陷驱动的相互作用不太普遍，并且观察到由沙丘的凸状下游隆起迁移引起的相互作用，这在风沙丘中尚未见报道。尽管周围流体和沙丘大小存在差异，但相互作用的空间密度与风沙新月形沙丘场的密度一致。尽管无处不在，但与不存在杂散的区域相比，它们的存在对变形和相互作用没有可量化的影响，这表明这些短暂的特征仅影响瞬时通量。缺陷驱动的相互作用不太普遍，并且观察到由沙丘的凸状下游隆起迁移引起的相互作用，这在风沙丘中尚未见报道。尽管周围流体和沙丘大小存在差异，但相互作用的空间密度与风沙新月形沙丘场的密度一致。尽管无处不在，但与不存在杂散的区域相比，它们的存在对变形和相互作用没有可量化的影响，这表明这些短暂的特征仅影响瞬时通量。