Purpose

Suspended sediment (SS) transport in rivers is highly variable, making it challenging to develop predictive models that are applicable across timescales and rivers. Previous studies have identified catchment and hydro-meteorological variables controlling SS concentrations. However, due to the lack of long-term, high-frequency SS monitoring, it remains difficult to link SS transport dynamics during high-flow events with annual or decadal trends in SS transport. This study investigated how processes driving SS transport during high-flow events impact SS transport dynamics and trends observed over longer timescales.

Methods

Suspended sediment samples from the River Aire (UK) (1989–2017) were used to (i) statistically identify factors driving SS transport over multiple timescales (high-flow events, intra- and inter-annual) and (ii) conceptualize SS transport as a fractal system to help link and interpret the effect of short-term events on long-term SS transport dynamics.

Results and discussion

Antecedent moisture conditions were a dominant factor controlling event-based SS transport, confirming results from previous studies. Findings also showed that extreme high-flow events (in SS concentration or discharge) mask factors controlling long-term trends. This cross-timescale effect was conceptualized as high fractal power, indicating that quantifying SS transport in the River Aire requires a multi-timescale approach.

Conclusion

Characterizing the fractal power of a SS transport system presents a starting point in developing transferrable process-based approaches to quantify and predict SS transport, and develop management strategies. A classification system for SS transport dynamics in river systems in terms of fractal power could be developed which expresses the dominant processes underlying SS transport.

中文翻译：

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连接河流中悬浮泥沙运移的时间尺度：以提高预测的可传递性

目的

河流中悬浮泥沙（SS）的运输变化很大，这使得开发适用于时标和河流的预测模型具有挑战性。先前的研究已经确定了控制SS浓度的集水区和水文气象变量。然而，由于缺乏长期的高频SS监测，仍然难以将高流量事件期间的SS输送动态与SS输送的年度或十年趋势联系起来。这项研究调查了在高流量事件中驱动SS运输的过程如何影响SS运输动力学和在较长时间范围内观察到的趋势。

方法

来自英国艾尔河（1989-2017）的悬浮泥沙样品用于（i）在多个时间范围内（高流量事件，年内和年际）统计确定驱动SS迁移的因素，以及（ii）概念化SS迁移作为一个分形系统，可以帮助链接和解释短期事件对长期SS传输动力学的影响。

结果和讨论

先前的水分条件是控制基于事件的SS迁移的主要因素，这证实了先前研究的结果。研究结果还表明，极端高流量事件（SS浓度或流量）掩盖了控制长期趋势的因素。这种跨时标效应被概念化为高分形功率，表明量化艾尔河上的SS迁移需要采用多时标方法。

结论

SS运输系统的分形功率表征是开发基于可转移过程的方法以量化和预测SS运输以及制定管理策略的起点。可以开发一种基于分形功率的河流系统中SS运输动力学的分类系统，该系统表达了SS运输的主要过程。