Morphodynamics of Barrier Island Systems

Abstract

Barrier island systems, also referred to as multiple-inlet systems, are coastal environments with shallow, interconnected tidal basins that are fringed by a chain of elongated islands. Their geomorphology and tidal habitats encompass numerous transitional zones between the land and the sea that are rich in species specially adapted to the varying hydrodynamic conditions. Morphodynamics at mixed-energy barrier island coasts have been studied for several decades on the basis of aerial photographs, field observations and numerical or analytical models. A process-based understanding of the morphological response to the driving hydrodynamic forces, however, has still not been achieved. The aim of this study is to assess the system morphodynamics in response to the interaction of tidally- and wave-induced currents, wind stress and the availability of mobile sediments. The study area is the East Frisian Wadden Sea (Germany), a lagoon-type environment with intertidal flats that are sheltered by seven inhabited barrier islands; it belongs to the Wadden Sea extending along the southern North Sea coast. A state-of-the-art process-based model is applied as a hindcasting and experimental tool for the evaluation of relevant processes at short term (tidal cycle) to medium term (annual) time scales. The spatial scales encompass sand shoals (meso-scale) as typical morphological features at ebb-tidal deltas, to the entire system covering the upper shoreface, the barrier islands and the back-barrier basins (large-scale).