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

尽管在沿海和沙漠沙丘的研究不断取得进展，少得多的是已知的过程，保持沙丘流动性供应有限的景观。具体而言，在风、地形、植被和地表条件相互作用以维持植被稳定地貌中的活动沙丘的方式方面，仍然存在知识空白。此外，由于风蚀的临界条件波动不定，人们对控制中高纬度地区风成过程有效性的地表条件的季节性变化知之甚少。本研究计划建立在最近的实地和理论研究的结果，以建立在半干旱的加拿大北方大平原（NGP）的风成过程和沙丘流动性之间的经验关系。活动沙丘对于保持NGP的生物多样性至关重要，因为它们是需要松散的移动的沙子的濒危物种的重要栖息地。经济活动，特别是牧场放牧以及石油和天然气开发，在NGP沙丘系统中也很重要，但几乎没有基线信息可以帮助指导管理战略，以尽量减少负面影响，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。学生和我将首先评估高分辨率的气流和沙输运动力学，以描述控制供应有限的抛物线沙丘和井喷的发展和流动性的流动形式的相互作用和反馈机制。在一个平行的研究中，我们将建立气象变量和随时间变化的阈值之间的关系，当沙运输开始，以解决季节性对沙的可用性和运输率的影响。最后，我们将量化所需的植被覆盖的百分比，以减少沙丘流动性，以选定的量，通过测量季节性的沙丘在不同阶段的植被定植沙输运率。总体而言，这项研究将提供必要的投入，为长期目标，开发全面的过程响应模型，以预测环境影响的气候变化和经济发展对沙丘流动性的NGP。

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.