Development of simplified tools for erosion assessment and prediction in semi-alluvial clay-bed rivers

开发半冲积粘土河床侵蚀评估和预测的简化工具

• 批准号: 485102-2015
• 负责人: Rennie, Colin
• 金额: $ 1.82万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Engage Grants Program
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=584728
• 关键词: Development; simplified; tools; erosion; assessment

An alluvial river has bed and banks composed of sediment transported by the flow, thus is free to adjust its shape to convey best its incoming flow and sediment. Rivers in much of eastern Canada flow through regions comprised of cohesive glacial sediments, including glaciomarine clays. These rivers are semi-alluvial, in that they are incising into these non-alluvial substrates, yet portions of the channel bed may be covered with a surficial veneer of alluvial material. Given the glacial history of Canada, many if not most of its rivers can be characterized as semi-alluvial. Management of these rivers is a difficult challenge, because relatively little is known about erodibility of their cohesive bed sediments or their stable channel geometry. The proposed research will 1) improve and compare methods for measurement of the critical bed shear stress required to mobilize a cohesive clay bed material, and 2) develop a simplified approach to account for erodibility of clay bed material when defining stable river geometry for channel design purposes. In the first stage of the research, cohesive bed sediments from Feedmill Creek, Ottawa will be tested for critical shear stress using three different methods: fluvial shear stress in a piston flume, normal stress using an industry standard jet tester, and by surface shear strength using a novel device developed at the University of Ottawa. In the second stage of the research, the one-dimensional hydraulic model SWMHYMO will be adapted to predict equilibrium cohesive-bed channel dimensions subject to unsteady continuous full year discharge hydrographs. This project is a collaboration with JF Sabourin and Associates Ltd, who will utilize the research results to improve management of semi-alluvial rivers in Eastern Canada.

冲积河流的河床和河岸由水流搬运的泥沙组成，因此可以自由调整其形状，以最好地输送其流入的水流和泥沙。加拿大东部大部分地区的河流流经由粘性冰川沉积物组成的地区，包括冰海粘土。这些河流是半冲积的，因为它们切入这些非冲积基底，但部分河床可能覆盖着冲积材料的表层。鉴于加拿大的冰川历史，许多河流（如果不是大多数的话）可以被描述为半冲积河流。这些河流的管理是一项艰巨的挑战，因为人们对其粘性河床沉积物的可蚀性或稳定的河道几何形状知之甚少。建议的研究将1）改进和比较用于动员粘性粘土床料所需的临界床面剪应力的测量方法，2）开发一种简化的方法来解释粘土的可蚀性 河床物质时，为河道设计目的确定稳定的河流几何形状。在研究的第一阶段，粘性床沉积物从饲料厂溪，渥太华将测试临界剪切应力使用三种不同的方法：在活塞水槽中的河流剪切应力，正应力使用行业标准的射流测试仪，并通过表面剪切强度使用一种新的设备在渥太华大学开发。在第二阶段的研究中，一维水力模型SWMHYMO将适用于预测不稳定连续全年流量过程线的平衡粘性河床河道尺寸。该项目是与JF Sabourin and Associates Ltd的合作，后者将利用研究成果改善加拿大东部半冲积河流的管理。