Process‐Based Modeling of Coastal Dune Blowout Initiation, Development, and Stabilization

Abstract Coastal dune blowouts are key geomorphic features that drive landward sediment transport, dune mobility, and habitat diversity, yet their conditions of formation and evolution remain poorly quantified. Using the process‐based AeoLiS model under time‐invariant wind conditions and for idealized coastal dune settings, we simulate the spontaneous development, growth, and stabilization of blowouts or blowout‐like landforms from initially alongshore‐uniform dunes. The model couples wind‐driven sediment transport, evolving topography, and vegetation dynamics, including germination, lateral expansion, and vertical growth. Our simulations show that small initial perturbations in vegetation cover, rather than topography, trigger blowout formation. Blowouts emerge as deflation basins at the dune crest, where low vegetation amplifies erosion and sediment fluxes, forming depositional lobes downwind. As a new incipient foredune forms seaward, aeolian activity declines and vegetation re‐establishes in the deflation basin, stabilizing the blowout system. Sensitivity analyses reveal that blowout development is favored on steeper dunes under stronger winds, with sparse or patchy vegetation and low‐lying hinterlands. Vertical vegetation growth governs the stabilization phase, while germination and lateral expansion introduce stochastic variability in blowout patterns. Slightly oblique onshore winds enhance alongshore variability and landward migration, whereas low wind speeds or dense initial vegetation suppress blowout formation. These results demonstrate that coastal blowouts are ecomorphodynamic instabilities arising from tightly coupled interactions between sediment, vegetation, and the evolving topography. The findings provide a framework for predicting blowout formation under varying environmental conditions and offer guidance for dynamic dune management strategies that enhance dune mobility and habitat heterogeneity.