Satellite-derived Shoreline Change in Portugal (1984-2024)

Overview This dataset contains satellite-derived shoreline positions for mainland Portugal between 1984 and 2024, extracted from Landsat 5–9 and Sentinel-2 imagery using a semi-automated Modified Normalized Difference Water Index (MNDWI)-based shoreline detection workflow. The dataset includes: shoreline geometries extracted from satellite imagery; shoreline analysis transects generated along the Portuguese coastline; shoreline intersection distances measured along each transect for all available shoreline acquisition dates. The dataset was designed to support the analysis of long-term shoreline evolution, coastal erosion, shoreline variability, and sedimentary dynamics at regional to national scales. Temporal Coverage December, 1984 – December, 2024 Coordinate Reference System EPSG:3763 — ETRS89 / Portugal TM06 Files Included PRT_TRA_all.geojson GeoJSON file containing shoreline analysis transects used to quantify shoreline positional changes. Transects were systematically generated at 50 m intervals along the EMODnet Mean Sea Level (MSL) baseline. Attribute Type Description transect string Unique transect identifier code. beach_designation string Beach designation where the transect is located, according to official Portuguese coastal management regulations. municipality string First-Level Local Administrative Unit (LAU1) - Municipio, in Portuguese - where the transect is located, according to the Official Administrative Charter of Portugal (CAOP), 2025 version. geometry LineString Transect geometry. The first coordinate corresponds to the landward point and the second coordinate corresponds to the seaward point. Shoreline distances are measured relative to the landward point along the transect axis. PRT_SHOf_all.geojson GeoJSON file containing satellite-derived shoreline geometries extracted from Landsat and Sentinel-2 imagery. Shorelines were extracted using a semi-automated Modified Normalized Difference Water Index (MNDWI)-based segmentation workflow. Attribute Type Description date datetime Acquisition date and time of the satellite image used for shoreline extraction (UTC). satellite string Satellite mission used for shoreline extraction. Values include `L5` (Landsat 5), `L7` (Landsat 7), `L8` (Landsat 8), `L9` (Landsat 9), and `S2` (Sentinel-2). cloud_cover float Fraction of cloud-covered pixels associated with the satellite image scene, inherited from the original satellite metadata. georeferencing_accuracy float Estimated georeferencing accuracy or positional uncertainty associated with the satellite scene, inherited from the original satellite metadata and expressed in meters. mndwi_threshold float Threshold value applied to the Modified Normalized Difference Water Index (MNDWI) for shoreline segmentation. geometry MultiLineString Shoreline geometry extracted from satellite imagery. PRT_SHODIST_all.csv CSV table containing shoreline intersection distances measured along each transect for all available shoreline acquisition dates. Rows correspond to individual transects and columns correspond to shoreline acquisition datetimes. Attribute Type Description transect string Unique transect identifier code. beach_designation string Beach designation where the transect is located, according to official Portuguese coastal management regulations. municipality string First-Level Local Administrative Unit (LAU1) - Municipio, in Portuguese - where the transect is located, according to the Official Administrative Charter of Portugal (CAOP), 2025 version. YYYY-MM-DD HH:MM:SS float Shoreline position distance measured along the transect for the corresponding shoreline acquisition datetime, expressed in meters relative to the landward transect point. Methodological Notes - Shorelines were extracted from Landsat and Sentinel-2 imagery using a semi-automated MNDWI-based workflow.- Shoreline positions correspond to the intersection between extracted shoreline geometries and predefined shoreline analysis transects.- Transects were generated approximately perpendicular to the EMODnet MSL baseline at regular 50 m spacing intervals.- Shoreline distances are measured along the transect axis relative to the landward transect point.- Satellite image metadata, including cloud cover and georeferencing accuracy, were preserved from the original image products. Citation If using this dataset, please cite: Pais, D., Ponte-Lira, C., Almeida, L.P. & Taborda, R., 2026. Satellite-derived Shoreline Change in Portugal (1984-2024). Zenodo. DOI: 10.5281/zenodo.20346661 License Creative Commons Attribution 3.0 Unported (CC-BY-3.0)