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

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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.