Aeolian sand transport and mobility of supply-limited inland dunes in the semi-arid northern great plains of Canada

加拿大半干旱北部大平原供应有限的内陆沙丘的风沙输送和流动性

• 批准号: 355819-2008
• 负责人: Hugenholtz, Christopher
• 金额: $ 1.09万
• 依托单位: University of Lethbridge
• 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=431775
• 关键词: Aeolian; sand; transport; mobility; supply

Despite continued advances in coastal and desert dune research, much less is known about the processes that maintain dune mobility in supply-limited landscapes. Specifically, knowledge gaps remain for the manner in which wind, topography, vegetation and surface conditions interact to maintain active dunes in vegetation-stabilized landscapes. Furthermore, seasonal changes in surface conditions controlling the effectiveness of aeolian processes at mid- to high-latitudes are poorly understood owing to fluctuating threshold conditions for wind erosion. This research program builds on results from recent field and theoretical studies to establish empirical relations between aeolian processes and dune mobility in the semi-arid Northern Great Plains (NGP) of Canada. Active dunes are essential for maintaining biodiversity in the NGP because they serve as critical habitat for endangered species requiring loose, mobile sand. Economic activities, particularly rangeland grazing and oil and gas development, are also significant in NGP dune systems, but little baseline information exists to help guide management strategies that minimize negative impacts and that conserve valued landscape processes and ecosystem components. To this end, this research program has three interrelated objectives. Students and I will first evaluate high-resolution airflow and sand transport dynamics so as to characterize flow-form interactions and feedback mechanisms that control the development and mobility of supply-limited parabolic dunes and blowouts. In a parallel study we will establish relations between meteorological variables and time-varying thresholds when sand transport is initiated so as to resolve the effects of seasonality on sand availability and transport rates. Finally, we will quantify the percentage of vegetation cover required to reduce dune mobility to selected amounts by measuring seasonal sand transport rates of dunes in varying stages of vegetation colonization. Overall, this research will provide essential input for the long-term goal of developing comprehensive process-response models to predict environmental impacts of climate change and economic development on dune mobility in the NGP.

尽管沿海和沙漠沙丘研究不断取得进展，但在供应有限的景观中，人们对维持沙丘移动的过程知之甚少。具体来说，在风、地形、植被和地表条件相互作用以维持植被稳定景观中活跃沙丘的方式方面，知识差距仍然存在。此外，由于风蚀阈值条件的波动，人们对中高纬度地区控制风成过程有效性的地表条件的季节变化知之甚少。本研究项目建立在最近的实地研究和理论研究的基础上，旨在建立加拿大半干旱北部大平原（NGP）风沙过程与沙丘移动之间的经验关系。活跃的沙丘对于维持NGP的生物多样性至关重要，因为它们是需要松散流动沙子的濒危物种的重要栖息地。经济活动，特别是牧场放牧和石油和天然气开发，在NGP沙丘系统中也很重要，但几乎没有基线信息来帮助指导管理战略，以尽量减少负面影响，并保护有价值的景观过程和生态系统组成部分。为此，本研究计划有三个相互关联的目标。我和学生们将首先评估高分辨率气流和沙粒运输动力学，以表征流形相互作用和反馈机制，这些机制控制着供应有限的抛物面沙丘和井喷的发展和流动性。在一项平行研究中，我们将建立气象变量与沙输运开始时的时变阈值之间的关系，以解决季节性对沙可用性和输沙率的影响。最后，我们将通过测量不同植被定植阶段沙丘的季节性输沙率，量化将沙丘迁移减少到选定数量所需的植被覆盖百分比。总体而言，该研究将为建立综合过程响应模型以预测气候变化和经济发展对NGP沙丘移动的环境影响的长期目标提供必要的投入。