Short-term coastal dynamics and implications for energy infrastructure safety: insights from the Baltic Sea coast

Abstract

Safety and location suitability is a vital issue for offshore wind farms and their transmission infrastructure, including cable landing stations. Geomorphological and geological features are one of the key determinants of durability and operational reliability of energy infrastructure. We analyse the dynamics of the coastal zone at the two locations (Ustka and Lubiatowo) planned for the landfall of marine transmission infrastructure on the Polish southern Baltic coast. Average centennial coastal changes were determined by comparing the shoreline from 1875 (1:25,000 topographic map) and 2022 (LIDAR). Statistical rates of change were calculated using DSAS software by analysing changes in shoreline position (1:10,000 topographic maps and LIDAR) over 7 to 8 time intervals between 1985 (1986) and 2022. Over a period of one and a half centuries, in the Lubiatowo landfall area, there was slight local erosion (max. ~80 m; ~0.5 m/yr) and accretion (max. ~90 m; ~0.6 m/yr). In the Ustka area, the situation was similar, but the extent of the changes was greater - the shoreline retreated locally by ~270 m (~1.8 m/yr) and local accretion amounted to ~270 m. Analysis of changes in the position of the shoreline on a timescale of three decades (1985–2022) showed a slight expansion of the erosion areas and a shift of the erosion and accretion centres to the east, as well as higher rates, of both erosion and accretion, compared to the period 1875–2022. Locally, the average erosion rate in the Lubiatowo area was 1.7 m/yr and the average accretion rate locally reached 1.5 m/yr. Similar trends and magnitudes of changes occurred in the Ustka area, where the average erosion rate was 1.6 m/yr and the accretion rate 1.2 m/yr. These examples  of erosion-accretion systems show that data on the position of erosion and accretion centres as well as on the rate of change of the shoreline position are strongly dependent on the time intervals analysed. Therefore, it is necessary to analyse not only the current litho- and morphodynamic processes on the coast, but also the trends of change at different time scales, when determining the landfall sites of power cables and as the design of their protection.