Purpose

The sediment dynamics of (peri-)glacial catchments can be highly variable and complex. Understanding these dynamics and their underlying causes is not only of interest from a scientific perspective but also required to address the practical problems with which they are often associated. In order to better understand the sediment dynamics of glaciated mountainous catchments, suspended sediment fluxes in the 9.1 km² Djankuat catchment (North Caucasus, Russia) were monitored intensively during the 2017 ablation season.

Materials and methods

The intra-event suspended sediment dynamics were studied using a newly proposed simple hysteresis index (SHI), quantifying to what extent evolutions in sediment concentration are characterized by a clockwise or anticlockwise hysteresis loop.

Results and discussion

The resulting catchment suspended sediment yield was 1033 t km⁻² year⁻¹, with the glacier itself contributing 72% of the suspended sediment load. However, during rainfall events, also hillslope erosion in the proglacial area became a very significant sediment source. Clockwise hysteresis loops occurred in 61.8% of the events, while anticlockwise in 11.8%. On the other hand, only 47.8% of the total suspended sediment flux was transported during clockwise events. Our observations clearly indicate that events showing a stronger clockwise pattern (i.e., a higher SHI) are associated with a larger sediment input from the proglacial area.

Conclusions

Overall, our results provide data and insights on sediment dynamics in an understudied environment. They illustrate that the type and characteristics of sediment concentration hysteresis loops are to some extent linked to the dominant sediment sources during the event. As such, the proposed methodology and SHI may also help with a better understanding of sediment dynamics in other environments.

中文翻译：

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高加索北部一个小冰川山区流域的悬浮泥沙收支和事件内泥沙动力学

目的

（周围）冰川流域的沉积物动力学变化很大且复杂。从科学的角度来看，不仅要了解这些动力学及其根本原因，而且还需要解决这些动力学通常与之相关的实际问题。为了更好地了解冰川山区流域的泥沙动力学，在2017年消融季节期间，对9.1 km ² Djankuat流域（俄罗斯北高加索）的悬浮泥沙通量进行了集中监测。

材料和方法

使用新近提出的简单滞后指数（SHI）研究了事件内悬浮泥沙动力学，量化了顺时针或逆时针滞后回线表征沉积物浓度变化的程度。

结果和讨论

所得集水区的悬浮泥沙产量为1033 t km ^-2  year ^-1，冰川本身贡献了悬浮泥沙负荷的72％。但是，在降雨事件中，冰河地区的山坡侵蚀也成为非常重要的沉积物来源。61.8％的事件发生顺时针磁滞回线，而11.8％的事件发生逆时针磁滞回线。另一方面，顺时针方向仅输送了总悬浮泥沙流量的47.8％。我们的观察清楚地表明，显示出更强的顺时针模式（即，更高的SHI）的事件与来自冰河地区的更大的沉积物输入有关。

结论

总体而言，我们的研究结果提供了在研究不足的环境中有关沉积物动力学的数据和见解。他们表明，泥沙浓度滞后回线的类型和特征在一定程度上与事件期间主要的泥沙源有关。因此，建议的方法和SHI也可能有助于更好地了解其他环境中的沉积物动力学。