River Water Levels Across the Amazon Basin During the 2023 - SGB

In late 2023, the Amazon River Basin faced its most intense drought on record until then, with devastating consequences for ecosystems and river communities. Traditional stream gauges recorded historically low river levels, and satellite observations, including from the SWOT mission, offered a basin-wide perspective on this extreme event.
This article was published by one of the OWV partner, the Geological Survey of Brazil. 

Key findings:

• River Water Levels dropped by more than 3 meters below the annual average across most of the central Amazon, exceeding two to three times the usual variability.
• The SWOT satellite, with its 200 m spatial resolution, captured the timing and propagation of low water levels across the basin, outperforming classical nadir altimetry, especially during peak drought.
• SWOT’s measurements had higher agreement with in‑situ gauges than nadir altimeters, with lower error variance (standard deviation ~0.14 m vs ~0.29 m).

Why This Matters:

• It’s the first Amazon Basin‑wide characterisation of such an extreme hydrological drought using high-resolution satellite data.
• The study demonstrates SWOT’s potential for real-time monitoring of hydroclimatic extremes in remote, monitor-deprived regions.

Enhanced observations of this nature are essential for:

• Improved drought and flood anticipation
• Greater resilience in ecosystems and local water-dependent communities
• Support for climate change impact studies and management decisions in the region

Figure legend: Characteristics of the 2023 drought in the Amazon as observed by satellite altimetry. (a) Anomaly of the 2023 minimum river water levels compared to the long-term average at each virtual station; (b) Drought propagation observed by SWOT, estimated by the time difference between the 2023 minimum water level recorded every 200 meters by SWOT and that measured at the Obidos gauge station, located near the basin outlet.

This study showcases exactly the kind of satellite-enabled hydrological monitoring approach that aligns with the initiative.
This article, published by a partner of the One Water Vision initiative, SGB, is shared with pleasure to provide information about the work of our partners.

Find more here.
Daniel Moreira et al, Geological Survey of Brazil (SGB), 2025