The Dynamic Equilibrium Shore Model for the Reconstruction and Future Projection of Coastal Morphodynamics

Abstract

Sea level and coastline change are becoming increasingly important topics to the population living along the edge of the world’s oceans and seas. This is the case at the southern Baltic Sea coast where climate change and glacio-isostatic response cause a relative sea-level rise of up to 2 mm/y and where storms events lead to continuous coastal retreat. There is an increasing need of numerical models applicable for reconstruction and future projection of coastal morphogenesis within the frame of coastal zone management and planning. By adopting a concept of dynamic equilibrium changes of coastal profiles and three dimensional generalization of the generalized Bruun concept, a quantitative model Dynamic Equilibrium Shore Model (DESM) is elaborated to study coastal morphogenesis including the reconstruction of the geological past and projection to future on the decadal to centennial time scale. The DESM model requires data of historical coastline configuration derived from maps, a high-resolution modern Digital Elevation Model (DEM), relative sea-level change data, and modelling data of long-shore sediment transport capacity. This model is applied in the study to three research areas of the southern Baltic Sea (Swina Gate, Łeba coast and Hel Peninsula). Their developments represent distinct examples of morphodynamics at wave dominated coast: formation of barrier islands, development of open coasts and processes at sandy spits. This study concentrates on areas in particular vulnerable to erosion and destruction due to their geological build-up, the glacio-isostatic subsidence and an exposure to the westerly and northern wind and storm tracks.