Flow and sediment dynamics in river channels

本研究计划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)粗粒度河道中河沟和水塘尺度上的河流形态，（ii）在砂床河流的野外地点对波纹-沙丘过渡的流动特征进行实地测量，以及（iii）安大略省南部河床溪流的侵蚀。需要对小池单元进行系统的现场研究，目的是更完整地表征这些单元上方的湍流流场。还将对河床形态和沿流水池单元的流动特性进行计算机模拟。一维的河床高程序列将通过自回归模型进行模拟，并通过HEC-RAS（美国陆军工程兵团）等模拟程序沿着这些序列进行流动特性模拟。此外，关于沙床河流河床转变的进一步问题将在实地环境中得到解决。特别地，重点将放在从波纹到沙丘发生转变时的流动阻力和层质输运率的变化上。这将沿着位于Ganaraska河（安大略省南部）支流的油田场地进行。最后，安大略南部的一些河流是基岩河道（沉积岩）。这些基岩河道以相对平坦的沉积岩碎片为主。岩床溪流的演化在一定程度上是由裸露的基岩表面的特征以及岩石碎片被侵蚀的容易程度所控制的。然而，人们对这些碎片的可蚀性知之甚少。将进行实地和实验室实验，以进一步提高我们对安大略省南部基岩控制河流流域的水流和沉积物运输过程的认识。这一研究项目将大大有助于我们了解冲积和基岩河道的流动和沉积动力学。在当地，拟议的研究计划将加强我们对基岩控制的城市河流侵蚀问题和河道演变的理解

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