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首页> 外文期刊>Geografiska Annaler, Series A. Physical Geography >Changeability of Movable Bed-Surface Particles in Natural, Gravel-Bed Channels and Its Relation to Bedload Grain Size Distribution (Scott River, Svalbard)
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Changeability of Movable Bed-Surface Particles in Natural, Gravel-Bed Channels and Its Relation to Bedload Grain Size Distribution (Scott River, Svalbard)

机译：自然，砾石床渠道中可移动床面颗粒的变化性及其与床面粒径分布的关系（斯科特河，斯瓦尔巴特群岛）

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摘要

The presented paper analyses the variability of grain size distribution parameters of bedload transported by the gravel-bed Scott River (Svalbard) draining a glacier catchment with an area of 10km(2). The grain size distribution analysis is one of the basic elements of identification of the fluvial transport mechanisms in gravel-bed rivers. It is used for the determination of threshold values for bedload movement. It is also treated as an important indicator of the origin, routes of distribution, and conditions of transport and deposition of fluvial bedload. The field study in a natural proglacial gravel-bed channel was carried out at two reaches in the mouth section of Scott River. The study revealed relatively high temporal variability and similar mean parameters of grain size distribution in conditions of low discharges. Bedload transport rates reached a mean of 71.9-76.0kgd(-1) in channel cross-section. Bedload texture was dominated by gravels with a proportional contribution of the fine-grained fraction along with very fine-grained gravels (8-2mm) of 38.8%. The medium-grained fraction (16-8mm) constituted 33.7%, with a lower contribution from the coarse-grained fraction (32-16mm) of 23.2%, and the very coarse-grained fraction (64-32mm) of 4.4%. Two periods in the course of bedload transport and distribution of grain size distribution parameters were distinguished based on variation of hydro-meteorological conditions. The first half of the measurement period was distinguished by significantly higher values of daily loads and increased contribution of the coarse-grained and very coarse-grained fraction (28-31% and 6.2-6.6%, respectively). During this time, the river discharged up to 94% of bedload. This resulted in a clear tendency for riverbed scouring. The second half was distinguished by generally low daily bedload transport rates (<10kgd(-1)), an increase in contribution of fine- and very fine-grained gravels (42-55.6%), and a change in the tendency to aggradation. Grain size indices were more varied, and grains were usually finer and better sorted. Selective transport processes, often related to redeposition, were dominant in the channel. Along with an increase in flow velocity, conditions for material deposition became more variable. This was manifested in weaker sorting and an increase in grain diameter.
机译：本文分析了砾石河床斯科特河（Svalbard）排泄的冰川集水区面积为10 km（2）的河床荷载的粒度分布参数的变化。粒度分布分析是识别砾石河床河流运移机制的基本要素之一。它用于确定床移动的阈值。它也被视为河流床荷的起源，分布途径以及运输和沉积条件的重要指标。在斯科特河河口的两个河段进行了天然的冰河砾石层河床的野外研究。该研究表明，在低放电条件下，相对较高的时间变异性和相似的平均粒度分布参数。河床横截面的床载运输率平均达到71.9-76.0kgd（-1）。砾石占基层结构的主要部分，细颗粒的比例与细颗粒（8-2mm）的比例为38.8％。中粒分数（16-8mm）占33.7％，其中粗粒分数（32-16mm）为23.2％，极粗粒分数（64-32mm）的贡献较低，为4.4％。根据水文气象条件的变化，区分了基床运移和粒度分布参数分布的两个时期。测量期的前半部分以每日负荷的值明显较高以及粗粒和非常粗粒部分的贡献增加（分别为28-31％和6.2-6.6％）为特征。在这段时间内，河流排放了多达94％的河床。这导致了河床冲刷的明显趋势。下半年的特点是每日的床载运输量普遍较低（<10kgd（-1）），细粒和超细粒砾石的贡献增加（42-55.6％）以及凝集趋势的变化。粒度指数变化更大，并且谷物通常更细，分类更好。通常与再沉积有关的选择性转运过程在通道中占主导地位。随着流速的增加，材料沉积的条件变得更加可变。这表现为较弱的分选和晶粒直径的增加。

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