Understanding shoreline shifts along Romania's southern black sea coast: a multidecadal (1984–2024) satellite-based analysis

This study analyzes long-term shoreline change along Romania's southern Black Sea coast using satellite-derived observations from Landsat and Sentinel-2 spanning 1984–2024. A multi-decadal shoreline dataset was generated through automated image-based extraction and validated against in situ GNSS measurements, with coefficients of determination exceeding 0.85 at multiple sites, confirming reliability in this microtidal environment. Shoreline change rates were computed across nourished and non-nourished sectors. Sandy foreshore sectors prior to nourishment were consistently accreting, with mean rates of +0.17 to +0.97 m/yr and low variability. Following nourishment, responses were heterogeneous: zones A2, A5, A6 and B1 shifted to erosional or near-stable conditions (−0.83 to −0.02 m/yr), while zones A3, A4 and A7 maintained positive rates (+0.22 to +0.87 m/yr), in all cases with substantially increased variability. The observed heterogeneity confirms the need for long-term satellite-derived monitoring to evaluate nourishment performance and support adaptive management along microtidal, heavily engineered coastlines.