Satellite-Based Monitoring of Vegetation Health and Water Bodies Extent in Dry Periods and Under Drought Conditions

This study investigates the relations between the dynamics of satellite-based indicators of reservoir water extent and the stress of the surrounding vegetation during dry periods and in drought conditions. A qualitative and quantitative comparison was performed between the monthly values of indices as NDVI, NDMI, fAPAR and the changes in the water extent of the San Giuliano Reservoir (Southern Italy), also in terms of anomalies. The indices and the water extent were derived from Sentinel-2 data, and the analysis was performed for a four-year time period (2019–2023). The results suggest that the dynamics of the reservoir water extent can be used to detect dry periods and/or drought conditions, and that the vegetation state indicators can complement the analysis and reduce the source of uncertainty. Being based on the satellite data only, the analysis has the potential to be replicated elsewhere in the World, including data scarce environments.