Spatial and temporal patterns of aeolian sediment transport on an inland parabolic dune, Bigstick Sand Hills, Saskatchewan, Canada

Topographic changes from erosion pins and on-site meteorological data document the spatial and temporal patterns of aeolian sediment transport at monthly to annual timescales across an active parabolic dune within a vegetation-stabilized inland, prairie dune field. Over two years, the sediment budget, calculated from digital elevation models, shows that the total volume of erosion (9890 m 3) is greater than the amount of deposition (6990 m 3), indicating a net loss of 2900 m 3 of sediment (or ∼ 29% of eroded sediment) from the dune. Sediment erosion occurred mainly on the stoss slope (3600 m 3; ∼ 36% of eroded sediment), but also on the south (2100 m 3; ∼ 21%) and north sides of the dune head (1700 m 3; ∼ 17%), the blowouts along the arms (1740 m 3, ∼ 18%) and the crest (650 m 3; ∼ 7%). Erosion from the deflation basin is limited by surface roughness and armoring effects of a gravel lag deposit (100 m 3; ∼ 1%). Thus, the blowouts currently contribute to maintaining dune mobility because no other sediment input occurs from upwind. Sediment deposition onto the dune occurred primarily beyond the brink on the south and southeast lee slopes (5500 m 3; ∼ 80%), coinciding with the southeasterly resultant transport direction for November 2004–05. The net loss of about 2900 m 3 (∼ 29%) may be attributed to sediment carried in suspension over and beyond the dune. Correlation analysis between sediment transport and meteorological variables suggests that monthly to seasonal changes of surface conditions (e.g., vegetation cover, ground freezing, moisture) buffer the relative importance of temperature and precipitation on rates of sediment transport. Conversely, wind correlates well on a monthly to seasonal basis because it is a driver of transport under all types of surface conditions. Seasonal effects produce a complex interaction between wind, climate and surface conditions. This leads to a dynamic range of threshold velocities, which in turn causes spatial and temporal variations in transport-limiting and supply-limiting conditions. Collectively, these findings have implications for modeling parabolic dune morphodynamics and sediment transport in mid- to high-latitude inland settings.