Bend cutoff is a fundamental process shaping meandering rivers. Despite the widely accepted differentiation between neck and chute cutoffs, a significant knowledge gap persists regarding the factors responsible for the occurrence of each cutoff regime and the specific conditions triggering the regime. Here, we used field and photogrammetric data derived from a global set of 22 meandering rivers, stretching more than 5500 km in total river length, to disentangle the controlling factors behind the cutoff regime in meandering rivers. We found that whether a meandering river forms a chute rather than neck meander cutoff depends primarily on the variability of overbank discharges. Short-lived, high-magnitude overbank floods promote the formation of chute cutoffs, aided by (though not required) reduced riparian vegetation density, enhanced stream power, and flow confinement within the river valley. In contrast, neck cutoffs are prevalent in rivers characterized by limited variations in bankfull hydrology, typically associated with low-magnitude, long-lasting overbank floods. Distinct cutoff regimes also discernibly affected floodplain geomorphology, with a chute regime resulting in more frequent cutoff occurrences. Our results suggest that human-induced alterations of river hydrologic regime can potentially cause fundamental shifts in the cutoff behavior of meandering rivers, thus affecting sediment residence time and carbon fluxes in alluvial floodplains.

中文翻译：

---

水文驱动的蜿蜒河流截流状况调节

弯道截流是塑造蜿蜒河流的基本过程。尽管颈部和溜槽切断之间的区别已被广泛接受，但对于导致每种切断状态发生的因素以及触发该状态的具体条件，仍然存在重大的知识差距。在这里，我们使用了来自全球 22 条蜿蜒河流（河流总长度超过 5500 公里）的实地和摄影测量数据，来理清蜿蜒河流截流制度背后的控制因素。我们发现，蜿蜒河流是否形成急流槽而不是颈部蜿蜒截流主要取决于溢流流量的变化。短暂的、高强度的河堤洪水促进了河道断流的形成，这得益于（但不是必需的）河岸植被密度的降低、河流动力的增强以及河谷内的水流限制。相比之下，河颈截流在满岸水文变化有限的河流中普遍存在，通常与低强度、持久的漫滩洪水有关。不同的截流制度也明显影响了洪泛区的地貌，其中急流槽制度导致更频繁的截流发生。我们的研究结果表明，人类引起的河流水文情势的改变可能会导致蜿蜒河流的截流行为发生根本性变化，从而影响冲积洪泛区的沉积物停留时间和碳通量。