Ecohydrological dynamics of water stress in an arid coastal system using multitemporal remote sensing indices and land surface temperature

Arid and semi-arid environments are highly sensitive to climate variability and water scarcity, yet theecohydrological dynamics of many coastal deserts in southern Peru remain poorly understood. This studycharacterized the temporal and spatial dynamics of water stress in the district of Inclán (Tacna, Peru) usingmultitemporal Sentinel-2 and Landsat 8/9 imagery for 2017–2024, with TerraClimate variables as regionalhydroclimatic context. Vegetation and moisture were assessed with NDVI, NDMI, NDWI, and SAVI, and landsurface temperature (LST) was derived from Landsat thermal products. Standardized anomalies (z-scores) and acomposite water stress index (IEHV) were calculated to identify temporal changes and spatial patterns. Vegetationand moisture conditions were persistently low, with consistently low NDVI and NDMI and predominantly negative NDWI. LST showed a clear seasonal contrast, with higher, more homogeneous values in the warm season andmore heterogeneous spatial patterns in the cold season. Anomalies suggested a weak tendency toward higherwater stress in 2021–2024, which was not significant when the first year was excluded, whereas 2020 showed atemporary anomaly toward lower stress, associated with positive vegetation anomalies and the coolest surfacetemperatures of the series; its cause could not be established. Spatially, higher vegetation and moisture values appeared, on visual inspection, in drainage corridors, lowlands, and irrigated fields, while more exposed areasappeared drier and thermally more extreme. Integrating spectral and thermal indices allowed characterization ofecohydrological stress and its spatial heterogeneity in this arid coastal system, pending field validation.