COLLABORATIVE RESEARCH: Experimental Study of Downstream Fining in Coarse-Grained River Channels

这是一个为期两年的项目的更新，该项目的总体目标是通过砾石的沉淀和选择性沉积来研究下游的细化。到目前为止，在圣安东尼瀑布水力实验室（SAFHL） 50米长、0.3米宽的河道中，主要的结果是将下游的精细化程度提高了两倍，明确地表明，选择性沉积是一种有效的精细化机制，可以在实验室实验中进行研究。在约翰霍普金斯大学（JHU）的平行实验中，一种新型的彩色颗粒系统提供了预测SAFHL观察到的细化所需的分数输运数据库。这个阶段现在涉及到一系列的SAFHL运行，通道宽度为2.0 m；这将产生辫状地形，使研究横向分选和地形对下游细化的影响成为可能。JHU目前的分段输运项目将继续增加泥沙供给对再循环的影响以及小尺度沉积特征的影响。最后，麻省理工学院将同时进行一系列作业，以检查1.0米宽通道中的局部横向分选，以及不同沉积物几何形状和提取百分比的影响。这项研究似乎是工程水力学与河流沉积学之间的第一个真正的联系，代表了与泥沙输送力学相关的基础研究。

This is a renewal of a 2-year project whose overall goal is to study downstream fining by aggradation and selective deposition in gravels. The main results so far have produced downstream fining by a factor of two in a channel 50 m long and 0.3 m wide at the St. Anthony Falls Hydraulic Laboratory (SAFHL), demonstrating unequivocally that selective deposition is an effective fining mechanism and that it can be studied in laboratory experiments. In parallel experiments at Johns Hopkins University (JHU), a novel colored-grain system is providing the fractional-transport data base needed to perdict the fining observed at SAFHL. This phrase now involves a series of runs a SAFHL with a channel width of 2.0 m; this will produce braided topography, enabling invesitgation of the effect of lateral sorting and topography on downstream fining. The present fractional-transport program at JHU, will continue adding components on the effect of sediment feed versus recirculation and the influence of small-scale sedimentary features. Finally, a concurrent set of runs at MIT to examine local lateral sorting in a 1.0 m wide channel as well as the effects of varying deposit geometry and percent extraction is planned. This research seems as the first real connection between engineering hydraulics and fluvial sedimentology and represents fundamental research related to sediment transport mechanics.