What Did the Destruction of the Kakhovka Dam Do to Vegetation? Separating Flood, Reservoir and Irrigation Effects with Satellite Data

SAKSHI D. MASKE 

The Kakhovka Dam in southern Ukraine was destroyed on 6 June 2023. This could have changed vegetation in three ways: through the flood below the dam, the draining of the reservoir, and the loss of water for the irrigation canals. All three happened inside an active war zone.

I tested each pathway separately with MODIS NDVI at 250 m resolution for 2016–2024. Treated land was defined by what physically happened to it and compared with similar land in the same war zone. I made the analysis plan public before downloading any data, and later wrote two registered revisions, each before the extra data it needed were downloaded.

- **Flooded land** showed no detectable lasting loss of July–October greenness. Matched on terrain and land cover (59% of flooded pixels), the change was −0.004 NDVI (95% CI −0.021 to 0.013; placebo p = 0.42); over all flooded pixels it was +0.012 (−0.003 to 0.028). Floodplain wetlands are the exception (−0.04 to −0.06).
- **Irrigated farmland.** With independent 30 m irrigation maps (Baber et al., 2026), fields irrigated in 2019–2021 lost 0.18 NDVI (95% CI 0.15 to 0.21; a third of their 2016–2018 level) in 2023–2024 relative to cropland that was never irrigated, after a small step in 2022 (−0.03). The pre-registered rule calls this *suggestive*: the irrigated fields were already greener in 2019–2021, the years used to identify them, so the placebo test fails. An NDVI-based irrigation proxy used in the first two analyses agreed with the independent maps on only 16% of its "irrigated" pixels in Kherson Oblast.
- **The drained reservoir bed** changed the most: the area with NDVI above 0.3 grew from 86–100 km² in each year before the breach to 1,574 km² in 2024. Sentinel-2 agrees with MODIS within 18% where both can be compared.

In Kherson Oblast, previously irrigated cropland, 4% of the area, accounted for −0.008 of a −0.020 relative change in July–October NDVI between 2016–2018 and 2023–2024 (95% intervals exclude zero); the flood accounted for almost none. Satellite data clearly show what happened to the reservoir and point to a large loss of greenness where canal irrigation stopped, but separating that loss from the war's other effects remains uncertain.