Climate Change Driven Alongshore Variations of Directional Forcing of Sediment Transport on the Eastern Baltic Sea Coast

Eelsalu, M.; Soomere, T., and Jankowski, M.Z., 2024. Climate change driven alongshore variations of directional forcing of sediment transport on the eastern Baltic Sea coast. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 256-260. Charlotte (North Carolina), ISSN 0749-0208. This study addresses the impact of systematic changes in the wind and wave directions to the magnitude and direction of wave-induced sediment transport along the eastern Baltic Sea shores. The analysis is performed using the CERC approach in terms of potential net and bulk transport based on a recent reconstruction of hourly wave time series using the SWAN model with a spatial resolution of 1–3 nautical mile forced for 1990–2021 by ERA5 winds. The majority of alongshore sediment transport is driven by waves approaching from one or two narrow (±15°) ranges of directions. A large part of the study area experiences a delicate balance of alongshore transport under the impact of waves driven by south-western and (north-)north-western (N/NW) winds. These wave systems produce up to 80–90% of the total net and bulk transport. Significant changes have occurred to the directional distribution of this transport owing to a decrease in the contribution of waves from the NW or NNW in many sections of the study area. This change is mostly associated with the magnitude and frequency of such winds and obviously infringes the balance or even direction of sediment transport in sectors affected by bi-directional wave patterns. Climate change driven rotation of wind direction only affects the magnitude of sediment transport in coastal sectors that develop under the impact of a single-peak wind system.