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Anthropogenic drivers for exceptionally large meander formation during the Late Holocene
Anthropocene ( IF 3.3 ) Pub Date : 2020-09-15 , DOI: 10.1016/j.ancene.2020.100263
Cindy Quik , Jasper H.J. Candel , Bart Makaske , Roy van Beek , Maurice Paulissen , Gilbert J. Maas , Menno Verplak , Theo Spek , Jakob Wallinga

Large-amplitude meanders may form in low-energy rivers despite generally limited mobility in theses systems. Exceptionally large meanders which even extend beyond the valley sides have developed in the Overijsselse Vecht river (the Netherlands) between ca. 1400 CE (Common Era) and the early 1900s, when channelization occurred. Previous studies have attributed the enhanced lateral dynamics of this river to changes in river regime due to increased discharges, reflecting climate and/or land-use alterations in the catchment. This paper focuses on local aspects that may explain why exceptionally large meanders developed at specific sites. Through an integrated analysis based on archaeological, historical, and geomorphological data along with optically stimulated luminescence dating, we investigated the relative impact of three direct and indirect anthropogenic causes for the local morphological change and enhanced lateral migration rates: (1) lack of strategies to manage fluvial erosion; (2) a strong increase in the number of farmsteads and related intensified local land use from the High Middle Ages onwards; and (3) (human-induced) drift-sand activity directly adjacent to the river bends, causing a change in bank stability. Combined, these factors led locally to meander amplitudes well beyond the valley sides. Lessons learned at this site are relevant for management and restoration of meandering rivers in similar settings elsewhere, particularly in meeting the need to estimate spatial demands of (restored) low-energy fluvial systems and manage bank erosion.



中文翻译:

全新世晚期人为驱动因素导致巨大的曲折形成

尽管在这些系统中流动性通常受到限制,但在低能河流中仍可能形成大幅度的曲折。在约瑟夫河之间的Overijsselse Vecht河(荷兰),已经形成了异常巨大的蜿蜒曲折,甚至延伸到山谷两侧。公元1400年(通用时代)和1900年代初,发生了信道化。先前的研究将这条河流的横向动力增强归因于流量增加引起的河流状况变化,反映了流域内的气候和/或土地利用变化。本文侧重于本地方面,这可以解释为什么在特定地点会产生异常大的弯道。通过基于考古,历史和地貌数据以及光学激发发光测年的综合分析,我们研究了三种直接和间接的人为原因对局部形态变化和横向迁移率提高的相对影响:(1)缺乏管理河流侵蚀的策略;(2)从中世纪开始,农庄的数量就大大增加了,与此相关的当地土地集约化程度也很高;(3)(人为引起的)流沙活动直接邻近河弯,导致河岸稳定性发生变化。综合起来,这些因素在局部导致了远远超出山谷两侧的曲折幅度。在此站点上获得的经验教训与其他地方类似环境中蜿蜒河流的管理和恢复有关,特别是满足估计(恢复)低能耗河流系统的空间需求和管理河岸侵蚀的需求。

更新日期:2020-10-15
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