NASA SNWG/OPERA: Dynamic Surface Water Extent from Landsat and Sentinel Satellites

Global surface water extent observations derived from Landsat-8 and Sentinel-2A/B/C optical sensors, validated from April 2023 onward. The data is produced by NASA's Satellite Needs Working Group (SNWG) OPERA project to meet U.S. government agency stakeholder needs. Each product covers 109.8 km x 109.8 km UTM tiles at 30-meter pixel resolution and is distributed as a set of GeoTIFF files.

Use Cases

• Monitoring flood and drought extent over time based on the validated water classification layers.
• Analyzing land cover changes near water bodies using the provided land cover classification layer.
• Assessing observation confidence for hydrological models based on the associated confidence layers.
• Masking terrain and cloud shadows in satellite analysis using the terrain shadow and cloud classification layers.

Strengths

• Provides validated surface water observations with a documented start date of April 2023.
• Data is derived from a harmonized input product (HLS v2.0) combining Landsat-8 and Sentinel-2A/B/C sensors.
• Each tile offers multiple analysis layers, including water classification, confidence, land cover, and terrain shadow.
• Products use a standardized 30-meter spatial resolution over a consistent 109.8 km x 109.8 km UTM tile grid.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count and total dataset size are unknown, which may limit suitability assessment.
• The description notes known issues and caveats on usage, requiring review of the provided documentation.

Provenance

Source

NASA Satellite Needs Working Group (SNWG) OPERA Project.

Collection Method

Generated from Harmonized Landsat-8 and Sentinel-2A/B/C (HLS) surface reflectance data version 2.0.

Time Range

Beginning April 2023.

Freshness

Data collection began in April 2023; forward production for the Sentinel-1 radar-based product began in September 2024.

Geography

Near-global coverage over land.