The Global Coastal Transect Repository (GCTR): An analyis-ready, cloud-native data repository for coastal analytics

The Global Coastal Transect Repository (GCTR) is an extension of the Global Coastal Transect System (GCTS), which provides over 11 million cross-shore transects spaced at 100-meter intervals along the world's coastlines. This repository extends the GCTS framework by adding two attribute sets: Directional Coastline Proximity: To characterize the spatial coastal context, this set provides 12 distance measurements from each transect origin to the nearest OpenStreetMap (OSM) coastline. These measurements are calculated along fixed bearings at 30° intervals (0°, 30°, 60°, ..., 330°). This provides a simple yet powerful proxy for coastal orientation and climate exposure (e.g., wave protected vs. wave unprotected coasts). Coastal Exposure Metrics: To quantify the exposure of human assets to coastal processes, this set provides metrics derived from the Overture Maps global building footprints dataset. For each transect, it includes: The distance from the shoreline to the nearest building footprint. The distance from the OpenStreetMap coastline to the nearest building footprint. The total count of building footprints intersecting a 100-meter wide coastal zone centered on the transect. The total area (in square meters) of these intersecting building footprints. Structure and Format: The dataset is provided as a collection of GeoParquet files, partitioned by continent. Each row corresponds to a single coastal transect and contains the original GCTS attributes alongside the new derived attributes. Usage and Access: While the data is available here for download, we recommend direct cloud access for large-scale analytics via the CoCliCo STAC catalog. The coastpy Python library provides the primary interface for discovering, loading, and analyzing this data. For usage instructions and tutorials, please see the project repository: https://github.com/TUDelft-CITG/coastpy. Citation: When using this dataset, please cite the following two papers: For the foundational transect system (GCTS): Calkoen, F. R., Luijendijk, A. P., Vos, K., Kras, E., & Baart, F. (2025). Enabling coastal analytics at planetary scale. Environmental Modelling & Software, 183, 106257. https://doi.org/10.1016/j.envsoft.2024.106257 For the coastal exposure metrics and the directional coastline proximity: Calkoen, F. R., Luijendijk, A. P., Barli, P., Hemmes, J., Ranasinghe, R., & Nicholls, R. J. (2025). Global coastal exposure and future erosion impacts on sandy shores. Manuscript in preparation.