Characterization of agricultural cultivation areas between 2019-2023 in war zones of Eastern Ukraine using Sentinel-2 data

After the Russian Federation troops entered Ukrainian territory on February 24, 2022, significant damage occurred throughout the country. In areas experiencing continuous conflict, much of the agricultural land has become unsuitable for farming. We characterize the development of agricultural cultivation areas based on multiple spectral indices using Sentinel-2 imagery to reflect wartime effects for two test sites in Eastern Ukraine between 2019-2023. More specifically, we establish season-trend analysis, automatically detect structural ruptures as eventually associated to the conflict, and test for significant differences of the time series data w.r.t. the pre-invasion and post-invasion periods for the growing seasons. Our findings highlight the relevance of identifying agricultural cultivation areas and analyzing them through time series profiles, particularly with respect to the Normalized Difference Vegetation Index and Chlorophyll Index, to ultimately detect patterns of war-related impacts. Season-trend analysis-based decomposition of the time series reveals that the trend component for the CI-based indices is the most informative, showing a sharp decline during the onset of the war. Additionally, structural breaks observed in the CI-green index occur in very close temporal proximity to the invasion, suggesting that this chlorophyll index could serve as an interesting indicator for the onset of the conflict. Finally, changes between the pre-invasion and post-invasion periods are also highly statistically significant.