Fluvial bedrock incision is driven by the impact of moving bedload particles. Mechanistic, sediment‐flux‐dependent incision models have been proposed, but the stream power incision model (SPIM) is frequently used to model landscape evolution over large spatial and temporal scales. This disconnect between the mechanistic understanding of fluvial bedrock incision on the process scale, and the way it is modeled on long time scales presents one of the current challenges in quantitative geomorphology. Here, a mechanistic model of fluvial bedrock incision that is rooted in current process understanding is explicitly upscaled to long time scales by integrating over the distribution of discharge. The model predicts a channel long profile form equivalent to the one yielded by the SPIM, but explicitly resolves the effects of channel width, cross‐sectional shape, bedrock erodibility, and discharge variability. The channel long profile chiefly depends on the mechanics of bedload transport, rather than bedrock incision. In addition to the imposed boundary conditions specifying the upstream supply of water and sediment, and the incision rate, the model includes four free parameters, describing the at‐a‐station hydraulic geometry of channel width, the dependence of bedload transport capacity on channel width, the threshold discharge of bedload motion, and reach‐scale cover dynamics. For certain parameter combinations, no solutions exist. However, by adjusting the free parameters, one or several solutions can usually be found. The controls on and the feedbacks between the free parameters have so far been little studied, but may exert important controls on bedrock channel morphology and dynamics.

中文翻译：

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将取决于泥沙通量的河流基岩切开规模扩大到较长的时间尺度

河流基岩切口是由移动的基岩颗粒的冲击驱动的。已经提出了机械的，依赖于沉积物-流量的切口模型，但是流动力切口模型（SPIM）经常用于在大时空尺度上模拟景观演化。在流程规模上对河流基岩切缝的机械理解与长期建模方法之间的这种脱节，是定量地貌学当前面临的挑战之一。在这里，通过对排放分布进行积分，可以将根植于当前过程理解的河流基岩切缝的力学模型明确地扩展到长期尺度。该模型预测的是与SPIM生成的等效的信道长配置文件形式，但可以明确解决信道宽度的影响，横截面形状，基岩易蚀性和排放变化性。河道的长剖面主要取决于基岩运移的力学原理，而不是基岩切口。除了规定边界条件以指定上游的水和沉积物供应以及切入速率外，该模型还包含四个自由参数，它们描述了河道宽度的静态水力几何形状，河床载水量对河道宽度的依赖性。 ，床负重运动的阈值放电以及覆盖范围的动态变化。对于某些参数组合，不存在任何解决方案。但是，通过调整自由参数，通常可以找到一种或几种解决方案。到目前为止，对自由参数的控制和反馈之间的研究很少，