An Analysis-Ready Dataset of Sentinel-2 Water and Vegetation Indices for River Basin Monitoring: STAC and COG Based Data Access and Cloud-Native Organization
Abstract
River basins integrate hydrological, water-quality, and vegetation processes, requiring consistent observations of surface water and surrounding vegetation. Sentinel-2 Multispectral Instrument imagery provides frequent observations at spatial resolutions of up to 10 m. However, long-term basin-scale analysis requires repeated data discovery, retrieval, preprocessing, and quality control. This study presents an analysis-ready, cloud-native dataset of Sentinel-2-derived environmental indices for the Hwangnyonggang River Basin, South Korea (674.8 km2), covering January 2017 to August 2026. Sentinel-2 Level-2A scenes were searched through a SpatioTemporal asset catalog (STAC) application programming interface using spatial, temporal, and cloud-cover criteria. Required assets were selectively read from Cloud optimized GeoTIFF (COG) files through HTTP range requests. The imagery was processed by grid alignment, scene classification layer masking, and basin clipping. Three indices were then derived: the normalized difference water index, normalized difference chlorophyll index, and normalized difference vegetation index. The dataset also provides temporal composites, water masks, valid-observation counts, and basin-level statistics. All raster products are stored as COGs and indexed in a static STAC catalog constructed in a local environment, with links to their source observations. The dataset contains 2,503 raster assets totaling 17.19 GB. Water masks showed an intersection over union of 0.679 and an F1 score of 0.809 when compared with the Joint Research Centre (JRC) Global Surface Water (GSW) dataset. Data reuse was demonstrated by retrieving point and sub-basin time series through STAC search and COG partial reads without downloading complete rasters. Following the FAIR principles, the dataset provides an accessible and reusable resource for long-term monitoring and analysis of river-basin environments.