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: 2010
• 资助国家: 加拿大
• 起止时间: 2010-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=459575
• 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，但人们对在供应有限的景观中保持沙丘流动性的过程知之甚少。具体地说，在风、地形、植被和地表条件相互作用以在植被稳定的地貌中维持活跃沙丘的方式方面，仍然存在知识空白。此外，由于风蚀阈值条件的波动，人们对控制中高纬度风沙过程有效性的地表条件的季节变化知之甚少。这项研究计划建立在最近实地和理论研究的结果基础上，以建立加拿大半干旱的大平原北部(NGP)风沙过程和沙丘移动性之间的经验关系。活跃的沙丘对于维持NGP中的生物多样性至关重要，因为它们是需要松散、流动的沙子的濒危物种的关键栖息地。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，将负面影响降至最低，并保护有价值的景观过程和生态系统组成部分。为此，这项研究计划有三个相互关联的目标。学生和我将首先评估高分辨率的气流和沙粒输送动力学，以表征控制供应受限抛物面沙丘和井喷的发展和流动的流动形式相互作用和反馈机制。在一项平行研究中，我们将建立气象变量与沙子运输开始时随时间变化的阈值之间的关系，以解决季节性对沙子可获得性和运沙率的影响。最后，我们将通过测量沙丘在植被定居不同阶段的季节性沙粒输移率来量化将沙丘移动性减少到选定数量所需的植被覆盖率。总体而言，这项研究将为制定全面的过程-反应模型的长期目标提供必要的投入，以预测气候变化和经济发展对下一代沙丘移动性的环境影响。