Flow and sediment dynamics in river channels

这项研究方案涉及冲积和基岩河道中水流和泥沙动力学的各个方面。重点将放在(I)粗粒河道中冲沟和水池尺度的河流地貌，(Ii)沙床河流现场波纹-沙丘过渡段的流动特征的现场测量，以及(Iii)安大略省南部岩床溪流的侵蚀。需要对冲沟水池单元进行系统的实地研究，以实现对这些单元上方的湍流流场的更全面的描述。还将对冲刷池单元的床层形态和流动特性进行计算机模拟。根据HEC-RAS(美国陆军工程兵团)等模拟程序的自回归模型和沿这些序列的流动特性，将模拟一维系列的床面高程。此外，关于沙床河流的河床转变的进一步问题将在实地环境中讨论。特别是，将重点放在水流阻力和推移质输沙率的变化，因为发生了从涟漪到沙丘的过渡。这将沿着位于加纳拉斯卡河支流(安大略省南部)的一个实地地点实现。最后，安大略省南部的一些河段是基岩水道(沉积岩)。这些基岩河道以相对平坦的沉积岩碎屑为主。岩床水流的演化在一定程度上受控于裸露基岩表面的特征以及岩石碎片被侵蚀的难易程度。然而，人们对这些碎片的可腐蚀性知之甚少。将进行现场和实验室实验，以进一步加强我们对安大略省南部基岩控制的河流河段的水流和泥沙输送过程的了解。这项研究计划将对我们在冲积河道和基岩河道中的水流和泥沙动力学的知识做出重大贡献。在本地，拟议的研究计划将加强我们对基岩控制的城市溪流沿线的侵蚀问题和河道演变的了解。

This research proposal deals with various aspects of flow and sediment dynamics in alluvial and bedrock channels. Emphasis will be placed on (i) river morphology at the scale of riffles and pools in coarse-grained channels, (ii) field based measurements of flow characteristics across the ripple-dune transition at a field site in a sand-bed river, and (iii) erosion of rockbed streams in southern Ontario.  Systematic field studies of riffle-pool units need to be undertaken with a goal to achieve a more complete characterization of turbulent flow fields above such units. Computer simulations of both bed morphology and flow characteristics along riffle-pool units will also be undertaken. One-dimensional series of bed elevations will be simulated from autoregressive models and flow characteristics along such sequences from simulation programs such HEC-RAS (US Army Corps of Engineers). Moreover, further questions on bedform transitions in sand-bed rivers will be addressed in a field-based setting. In particular, emphasis will be placed on changes in flow resistance and bedload transport rates as the transition from ripples to dunes takes place. This will be achieved along a field site located on a tributary of the Ganaraska river (southern Ontario). Finally, some river reaches in southern Ontario are bedrock channels (sedimentary rocks). These bedrock channels are dominated by relatively flat sedimentary rock fragments. The evolution of rockbed streams is controlled in part by the characteristics of the exposed bedrock surfaces and how easily rock fragments can be eroded. Little is know, however, on the erodibility of these fragments. Both field and laboratory experiments will be conducted to further enhance our knowledge of flow and sediment transport processes along bedrock-controlled river reaches in southern Ontario. This program of research will contribute significantly to our knowledge of flow and sediment dynamics in both alluvial and bedrock channels. Locally, the proposed program of research will enhance our understanding of erosional problems and channel evolution along bedrock-controlled urban streams