Collaborative Research: Experimental Study of Downstream Fining in Coarse-grained River Channels

最近，从各种实地观察中可以清楚地看到， 在加积河流系统中， 大部分是由于粗碎屑的选择性沉积。 然而，在这方面， 通过选择性沉积进行分选的研究还从未进行过 在受控条件下进行。 缺少一套 下游分选的参考数据更令人震惊， 根据最近提出的理论 该项目的主要目标是实现 进行了一系列关于选择性运输的基础实验， 在分选不良的砾石沉积物中沉积。 大部分 实验将在圣安东尼的一个大通道中进行。 福尔斯水力实验室。 在那里，我们将从 在约50米的距离上分选不良的砂砾混合物。 的 主要变量将是沉积物进料速率（因此 沉积）和通道形式（直的、弱弯曲的、辫状的）。 此外，我们还将对沉积物进行详细测量 约翰霍普金斯小水槽中的输运和表面结构 大学 这些数据将用于开发基于表面的 将用于建模排序的传输公式 在大水槽中观察。

Recently it has become clear from a variety of field observations that downstream size decrease in aggrading river systems is caused in large part by selective deposition of coarse clasts. However, sorting by selective deposition has never been studied systematically under controlled conditions. The absence of a set of reference data on downstream sorting is even more striking in light of the number of theories that have been advanced recently to explain it. The main goal of the proposed project is to carry out a series of basic experiments on selective transport and deposition in poorly sorted gravelly sediments. Most of the experiments will be conducted in a large channel at the St. Anthony Falls Hydraulic Laboratory. There we will produce deposits from a poorly sorted sand-gravel mix over a distance of about 50 m. The main variables will be rate of sediment feed (and hence deposition), and channel form (straight, weakly sinuous, braided). In addition we will make detailed measurements of sediment transport and surface texture in a smaller flume at Johns Hopkins University. These data will be used to develop surface-based transport formulas that will be used in modeling the sorting observed in the large flume.