Particle kinematics and sediment transport processes in mountain streams: the role of sediment supply and flow regimes

山间溪流中的颗粒运动学和沉积物输送过程：沉积物供应和流动状态的作用

• 批准号: 249673-2012
• 负责人: Hassan, Marwan
• 金额: $ 2.33万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 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=570681
• 关键词: Particle; kinematics; sediment; transport; processes

Despite a large body of research on sediment transport, no agreement has been established on a governing equation appropriate to the estimation of bulk sediment movement in stream channels over time. In part, this is due to the irregularity of the granular beds acted upon by temporally and spatially variable fluid forces, bedsurface structures and armouring, and episodic sediment supply. Indeed, bed surface composition (texture and structure) and the sediment supply/storage regime both play important roles in controlling channel stability and regulating sediment transport in streams. Mountain streams are especially complex; stones form structures that exert significant influences on both the mobility of the bed sediment and the nature of the flow. In addition, these streams episodically receive large inputs of sediment from adjacent hillslopes, potentially dominating channel morphology and system dynamics. Although many studies have investigated the dynamics of lowland rivers with less variable sediment and flow regimes, little research has focused on mountain streams. The proposed research will focus on a set of questions related to the impact of sediment supply and flow regimes on the variability of particle displacement and retention, streambed texture and structure, bed stability and channel morphology. Understanding which portions of the stream bed are mobile, the frequency of sediment movement, and channel response and recovery all constitute important pre-requisites for the accurate prediction of those flow and sediment disturbances that can be attributed to climate and land-use changes on stream ecosystem. This study will focus on small-scale experimental units (laboratory and field), in order to gain in-depth mechanistic understanding of linkages between sediment supply and flow regime with channel stability and morphology. A key objective is to use the experimental and field results to develop and parameterise models so as to enable predictions of channel response/recovery in relation to changes in sediment and flow regimes in mountain streams. Field observations will be complemented by laboratory experimentation, in turn facilitating the development of protocols and methods for future field-based research. Quantification of the relation between channel response/recovery and changes in flow and sediment supply regimes will be based on: (a) description of individual particle displacement and retention, and (b) quantification of sediment supply-transport relations.

尽管对泥沙输移进行了大量的研究，但对于适用于估计河道中泥沙随时间推移的控制方程还没有达成一致意见。这在一定程度上是由于颗粒床的不规则性，作用于时间和空间上可变的流体力、床面结构和装甲，以及幕式沉积物供应。事实上，河床表面组成(结构和结构)和泥沙供应/储存制度在控制河道稳定性和调节河流泥沙输送方面都发挥着重要作用。山间溪流特别复杂；岩石形成的结构对河床沉积物的流动性和水流的性质都产生了重大影响。此外，这些溪流时不时地从邻近的山坡接收大量泥沙输入，潜在地主导着河道形态和系统动力学。虽然许多研究调查了泥沙和流态变化较少的低地河流的动态，但很少有研究集中在山区溪流上。 拟议的研究将集中在一系列问题上，这些问题涉及泥沙供应和水流制度对颗粒置换和滞留的变异性、河床结构和结构、河床稳定性和河道形态的影响。了解河床的哪些部分是可移动的、泥沙运动的频率以及河道的响应和恢复都是准确预测可归因于气候和土地利用变化的河流生态系统的水流和泥沙扰动的重要先决条件。这项研究将集中在小型试验单元(实验室和现场)，以便从机理上深入了解泥沙供应和水流状况与河道稳定性和地形之间的联系。一个关键的目标是利用实验和现场结果来开发和参数化模型，以便能够预测与山区河流泥沙和水流状况变化有关的河道响应/恢复。实地观察将得到实验室实验的补充，这反过来又有助于为今后的实地研究制定方案和方法。河道响应/恢复与水流和泥沙供应制度变化之间关系的量化将基于：(A)描述单个颗粒的移动和滞留，以及(B)泥沙供应-运输关系的量化。