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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Channel pattern of proglacial rivers: topographic forcing due to glacier retreat
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Channel pattern of proglacial rivers: topographic forcing due to glacier retreat

机译：冰河河流道模式：冰川退缩造成的地形强迫

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Glacier retreat leads to changes in channel pattern during deglaciation, in response to changing water, sediment and base level controls. Recent ongoing retreat at Skaftafellsj?kull, Iceland (c. 50m per year since 1998) has resulted in the formation of a sequence of river terraces, and several changes in river channel pattern. This paper compares widely used models of river channel pattern against the changes observed at Skaftafellsj?kull. Doing this reveals the role of topographic forcing in determining proglacial channel pattern, whilst examining the predictive power and limitations of the various approaches to classifying river channels. Topography was found to play a large role in determining channel pattern in proglacial environments for two reasons: firstly, glacier retreat forces rivers to flow through confined moraine reaches. In these reaches, channels which theory predicts should be braided are forced to adopt a single channel. Secondly, proximal incision of proglacial rivers, accompanied by downstream aggradation, leads to changes in slope which force the river to cross channel pattern thresholds. The findings of this work indicate that in the short term, the majority of channel pattern change in proglacial rivers is due to topographic forcing, and that changes due to changing hydrology and sediment supply are initially relatively minor, although likely to increase in significance as deglaciation progresses. These findings have implications for palaeohydraulic studies, where changes in proglacial channel pattern are frequently interpreted as being due to changes in water or sediment supply. This paper shows that channel pattern can change at timescales faster than hydrological or sediment budget changes usually occur, in association with relatively minor changes in glacier mass balance.
机译：冰川退缩会导致冰川融化过程中河道模式的变化，以响应不断变化的水，沉积物和基准面控制。最近在冰岛的Skaftafellsj？kull进行的撤退（自1998年以来每年约5000万）导致一系列河阶地的形成，以及河道格局的若干变化。本文将广泛使用的河道模式与在Skaftafellsj？kull观测到的变化进行了比较。这样做揭示了地形强迫在确定冰川通道样式中的作用，同时检查了对河道进行分类的各种方法的预测能力和局限性。人们发现地形在决定冰河环境中的河道模式中起着重要作用，其原因有两个：首先，冰川退缩迫使河流流经狭窄的冰ora河段。在这些河段，理论上应该编织的渠道被迫采用单一渠道。其次，冰川河的近端切口，伴随下游的积水，导致坡度变化，迫使河流越过河道型式的阈值。这项工作的发现表明，在短期内，冰河河流中的大部分河道模式变化是由于地形强迫所致，而水文和沉积物供应变化所引起的变化最初相对较小，尽管随着冰消作用的重要性可能会增加。进展。这些发现对古水力研究具有重要意义，在该研究中，冰河通道模式的变化经常被解释为是由于水或沉积物供应的变化。本文表明，与冰川水量平衡的相对较小的变化有关，河道模式的变化速度比通常的水文或沉积物预算变化快。

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