Wind and Sediment Transport Pattern Inside a Small Trough Blowout During Opposing Wind Conditions

Abstract In recent decades, significant anthropogenic impact has modified European coastal dunes, leading to the development of blowouts, a common wind erosional feature. This study investigates a small trough blowout altered by closed human footpath since several decades at Canet-en-Roussillon during both offshore and onshore wind events. Campaigns consisting of 26 2D ultrasonic anemometers deployed at 0.30 m across the entire surface of the blowout. Simultaneously, sediment transport runs were conducted using Hilton sand traps. The results revealed the blowout as a double-nested system with distinct wind dynamics driven by bidirectional wind regimes. Section 1 (landward) is subjected to oblique incident winds, whereas Sect. 2 (seaward) is governed by parallel flow. The interplay between the winds complexity and the morphology of the blowout results in relatively low sediment transport rates. Although offshore winds dominate the environment, it is the onshore winds that generate the highest transport rates. This dynamic raises important questions about the long-term stability and lifespan of such systems.