Sediment entrainment and transport in sparsley vegetated arid and semi arid environments

稀疏植被干旱和半干旱环境中泥沙的夹带和输送

• 批准号: 7427-2007
• 负责人: Nickling, William
• 金额: $ 2.72万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2009
• 资助国家: 加拿大
• 起止时间: 2009-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=420415
• 关键词: Sediment; entrainment; transport; sparsley; vegetated

Despite recent advances in wind erosion research, little detailed knowledge is currently available regarding the localized atmospheric, surficial and textural variables that directly control both sediment supply and available shear stress at the bed. The proposed research program builds on the results and experience gained from our recent field and laboratory studies and will focus on specific surficial and textural factors that control the sediment supply and transport of sand and dust. Results of this work will provide necessary input for the long-term goal of developing a comprehensive sediment transport model accounting for the temporal and spatial variability of dust emissions and dust storm development. The proposed research program has two distinct but interrelated components. We will first carry out a detailed field and laboratory wind tunnel evaluations of the Raupach et al. (1993) shear stress partitioning model and the more recent Okin and Gillette (2006) non-equilibrium lateral cover model using simulated vegetation elements having a range of porosities, sizes, aspect ratios, spacing patterns and surface cover. This work will be undertaken in the Department of Geography, University of Guelph 15m sediment transport tunnel using newly developed instrumentation that can simultaneously and independently measure the wind force on individual plant elements and the bare intervening surface as well as the sediment transport rate at sampling frequencies from 1 to 10 Hz. A complimentary field investigation will also be carried out at the USDA Jornada Experimental Range, New Mexico, which is located in an arid environment dominated by mesquite and creosote shrubland. At several sites, having different vegetation types and per cent cover high speed measurements of wind speed, direction will be made above and within the sparse vegetation canopies using traditional anemometry. Surface drag and drag on individual elements will also be made using unique instrumentation developed at Guelph. Sediment transport rates measured within the vegetation by electronic saltation sensors will be related to the wind flow, surface shear stress distribution and vegetation characteristics.

尽管最近在风蚀研究方面取得了进展，但目前关于直接控制沉积物供应和河床可用剪应力的局部化大气、地表和质地变量的详细知识很少。拟议的研究方案建立在我们最近的实地和实验室研究的结果和经验的基础上，并将重点放在控制沙尘沉积物供应和输送的特定表面和质地因素上。这项工作的结果将为制定一个综合泥沙输送模型的长期目标提供必要的投入，该模型考虑到粉尘排放和沙尘暴发展的时间和空间变异性。拟议的研究计划有两个截然不同但相互关联的组成部分。我们将首先对劳巴赫等人进行详细的现场和实验室风洞评估。(1993)的剪应力划分模型和最近的Okin和Gillette(2006)的非平衡侧向覆盖模型，该模型使用具有一系列孔隙度、大小、长宽比、间距模式和地表覆盖的模拟植被元素。这项工作将在圭尔夫大学15米泥沙输送隧道地理系进行，使用新开发的仪器，可以同时和独立地测量单个植物元素和裸露介入面上的风力以及在1至10赫兹的采样频率下的泥沙输送速率。还将在新墨西哥州的USDA Jornada实验场进行免费的实地考察，该试验场位于以梅斯奎特和杂色油灌木为主的干旱环境中。在具有不同植被类型和覆盖率的几个地点，将使用传统的风速测量法在稀疏的植被冠层上方和内部进行风速、风向的高速测量。还将使用Guelph开发的独特仪器对单个元素进行表面拖动和拖动。利用电子跃变传感器测量植被内的泥沙输移率将与风流、地表剪应力分布和植被特征有关。