River channels often develop channel belts—wider corridors imprinted by past channel occupation—that record past landscape dynamics and form widespread aquifers. Controls on channel belt width for braided rivers have been inferred through physical experiments that evolve an initially straight channel and yield an interpreted, quasi‐equilibrium form. Yet uncertainties remain regarding the independent effects of discharge, slope, and time on channel belt dimensions and the morphodynamic phenomena that coincide with channel belt development. To address these uncertainties, I conducted four experiments that independently varied discharge and bed slope for flow over a bed of medium sand (D₅₀ = 0.42 mm). The laboratory basin (37 m long, 2.7 m wide) was 200 times longer and nine times wider than the width of the largest initial channel, which reduced boundary effects and provided a baseline to measure downstream variability in channel belt width. Transitions in channel belt growth rate occurred in concert with three phases captured by time‐resolved topography data: (1) meandering; (2) braiding, with logarithmic growth of the channel belt; and (3) maturity, with slowing, localized growth due to decreasing flow depth. A dimensionless framework involving discharge, slope, and sediment grain size collapses the growth trajectories of the channel belts to a common trend. In comparison, for natural cases, discharge is the dominant predictor of channel belt width (w_cb ~ Q^0.55). The time dependence of channel belt width in the experiments suggests that the widths of isolated, ancient channel sand bodies are wider than their formative channels.

中文翻译：

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辫状河如何发展河道带？

河道经常形成河道带，即过去的河道占领留下的更宽阔的走廊，记录了过去的景观动态并形成了广泛的含水层。已经通过物理实验推断出对辫状河流的河道带宽度的控制，这些实验演化出了最初的笔直河道并产生了一种解释性的准平衡形式。然而，关于流量，坡度和时间对河道带尺寸和与河道带发展相吻合的地貌动力学现象的独立影响仍然不确定。为了解决这些不确定性，我进行了四个实验，分别改变了中砂床上的流量和床坡度（D ₅₀ = 0.42毫米）。实验室盆地（长37 m，宽2.7 m）比最大初始河道的宽度长200倍，宽9倍，这减少了边界效应，并为测量河道带宽度的下游变化提供了基线。河道带增长率的变化与时间分辨地形数据捕获的三个阶段一致：（1）蜿蜒；（2）编织，通道带对数增长；（3）成熟度，由于水深的减小，局部生长缓慢。涉及流量，坡度和沉积物粒度的无因次框架使河道带的生长轨迹崩溃，成为一个共同趋势。相比较而言，对于自然的情况下，放电通道是皮带宽度的主导预测值（瓦特_CB  〜  Q^0.55）。实验中河道带宽度的时间依赖性表明，孤立的古老河道砂体的宽度比其形成河道宽。