Atlas › China › Water change

Poyang Lake

China's largest freshwater lake in a drought year against a flood year.

9,279.1 hectares changed — water gone · Before: 1 Aug 2020 – 15 Oct 2020 · After: 1 Aug 2022 – 15 Oct 2022 · 29.100, 116.200

BEFORE 2020-10

AFTER 2022-10

Drag to compare

9,279.1 haarea changed

3areas flagged

10,020 haarea examined

2satellites used

What SCOPE found

Water disappeared — 9,275.3 ha
near the centre of the area · 86% sure

Water disappeared — 1.4 ha
5.2 km south-east · 78% sure

Water disappeared — 2.4 ha
5.0 km south-east · 74% sure

How sure is this?

The strongest area (#1) has 86% confidence. It appears in 6 of 6 later clear images, so it is not a one-day artefact. Radar could not confirm or rule them out (normal for vegetation changes), so the result rests on repeated clear optical views and the seasonal comparison. Only 0% of the area had clear optical views, so some change may be hidden by cloud. Note: Optical imagery was unusable (cloud); results rely on Sentinel-1 radar only. Confidence measures how strong the evidence for real surface change is; it does not identify the cause or who did it.

How it was measured

SCOPE used Sentinel-2 optical imagery at 10 m, cloud-masked and combined over each period, Sentinel-1 radar as an independent check , and the same season in earlier years so normal seasonal change is not reported as real change. The analysis took 15 seconds.

Now try it on a place you know

If SCOPE is right about somewhere you know well, you can trust it somewhere you do not. 5 scans a day, free, no card.

Scan your own place