Carvalho, A.M.C.; Ellis, J.T.; Lamothe, M., and Maia, L.P., 2016. Using wind direction and shoreline morphology to model sand dune mobilization.
This paper aims to establish a relationship between wind direction, shoreline position, and aeolian transport directions. Ceará State in NE Brazil, which mainly comprises barchans, barchanoids, parabolic dunes, and large flattened composed dunes was used to formulate and test a dune transport model that can be applied to north and east facing beaches. The headland-bay beaches of Ceará progressively increase in angle from E to W. This is accompanied by a corresponding change in the near-beach dune migration direction. A significant change in the wind pattern for the northern portion of Ceará was found, which resulted in a shift in dune migration from E-W to ENE-WSW as the shoreline orientation changed from NW-SE to W-E. The different aeolian transport conditions along the stretches of the headland-bay beach gradually shifted from transport parallel to the shoreline to unimpeded aeolian transport that moves sediments inland. Beach feeding occurs from headland bypass as dunes occupy the area landward of the headland. A zone of composite wind transport directions, winds carrying sand directly from the beach and those transporting sediment landward of the headland, was identified. This variation of wind transport conditions is confirmed by the dune morphology and influenced by the relationship between shoreline position and wind angle approach. The proposed model uses the sine of the angle between wind direction and shoreline orientation to predict aeolian transport and determines the volume of sediment transported by the wind. This model identifies stretches of shoreline under different aeolian transport directions and exhibits compatibility with measured dune migration.