Data from: Anthropogenic drivers for the rapid formation of extremely large meanders during the Late Holocene

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.

尽管低能河流系统通常侧向活动性有限，但仍可能形成大振幅曲流。公元1400年左右至1900年代初河道渠化期间，荷兰的奥弗赖塞尔费赫特河（Overijsselse Vecht）形成了甚至延伸至谷坡之外的超大型曲流。此前研究将该河侧向活动性增强归因于流量增加导致的河流水文情势变化，这反映了流域内气候与/或土地利用的改变。本研究聚焦于可解释为何超大型曲流仅在特定区域形成的局地因素。通过整合考古学、历史学与地貌学数据，并结合光释光测年（Optically Stimulated Luminescence Dating）技术，本研究针对导致局地地貌演变与侧向迁移速率提升的三类直接及间接人为成因开展了相对影响程度分析：其一，缺乏河流侵蚀防控策略；其二，自中世纪盛期起，农庄数量大幅增长，相关局地土地利用强度提升；其三，（人为诱发的）河弯邻近区域风沙活动加剧，导致河岸稳定性发生改变。上述因素共同作用，使得该区域的曲流振幅远超谷坡范围。本案例所得经验可为其他类似环境下曲流河流的管理与修复工作提供参考，尤其有助于满足（修复后的）低能河流系统的空间需求评估及河岸侵蚀防控需求。