Hydroclimatic trends in Southeastern Türkiye from multi-source earth observation data

Southeastern Türkiye, located in the upper Tigris–Euphrates basin, is increasingly exposed to hydroclimatic stress under semi-arid conditions. This study integrates multi-source remote sensing and reanalysis datasets, including ERA5-Land, CHIRPS, MODIS NDVI, GRACE MASCON, and JRC Global Surface Water, within a Google Earth Engine–QGIS workflow to assess regional hydroclimatic trends during 2000–2020, with GRACE/GRACE-FO terrestrial water storage evaluated over 2002–2020. Spatial trend analysis was complemented by Mann–Kendall significance testing and Sen’s slope estimation to strengthen statistical interpretation. Results indicate warming, vegetation greening, and declining terrestrial water storage over the study period, based on non-parametric trend analysis of annual aggregated observations. Because hydroclimatic time series may exhibit residual temporal autocorrelation, statistical significance should be interpreted cautiously and primarily as exploratory regional trend evidence rather than definitive inferential proof. The coexistence of vegetation greening and declining terrestrial water storage indicates contrasting regional environmental trends between vegetation dynamics and integrated water storage. However, the present analysis does not directly quantify irrigation withdrawals, groundwater abstraction, or other anthropogenic drivers; therefore, the causes of these contrasting trends cannot be determined from the current datasets alone. These findings should therefore be interpreted as exploratory regional evidence rather than as attribution of specific climatic or anthropogenic drivers. Persistent warming and declining terrestrial water storage highlight the importance of continued monitoring of regional water-resource conditions. These findings provide a reproducible framework for multi-variable regional hydroclimatic trend assessment.