Compare two dams
Xiaowan
Checked against optical · SWOT agreement r = 0.85
Latest 2026-10: 121.7 km²; same-month median 125.1 km² over 9 other years (rank 30th percentile).
Nuozhadu
Raw, uncalibrated radar · SWOT agreement r = 0.34
Latest 2026-10: 197.3 km²; same-month median 204.2 km² over 9 other years (rank 30th percentile).
Nuozhadu caveat: radar and optical areas differ here mainly because of mixed shoreline pixels (a 1–2 pixel band), and radar agreement with SWOT water height is weak, so month-to-month changes at Nuozhadu should be read with caution.
Water area is a signal, not storage volume. Shown as % of each dam's own median so different-sized reservoirs can be compared. Radar: our processing of Copernicus Sentinel-1.