Detecting Divergent Hydroclimatic Trends in Southeastern Türkiye Using Multi-Source Remote Sensing and Mann–Kendall Trend Analysis

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 vulnerability between 2000 and 2020. Spatial trend analysis was complemented by Mann–Kendall significance testing and Sen’s slope estimation to strengthen statistical interpretation. Results reveal statistically significant warming (τ = +0.543, p < 0.001), significant vegetation greening (τ = +0.562, p < 0.001), and significant decline in integrated terrestrial water storage (τ = -0.368, p = 0.030), while precipitation and near-surface soil moisture exhibited no statistically significant regional monotonic trends despite marked spatial heterogeneity. The coexistence of vegetation greening and declining terrestrial water storage suggests that apparent agricultural productivity gains may partly reflect irrigation-driven intensification rather than improved hydrological resilience. Persistent warming combined with increasing anthropogenic water demand indicates growing long-term water security pressure across the region. These findings provide a statistically robust and transferable framework for hydroclimatic vulnerability assessment in semi-arid river basins experiencing coupled climatic and human-induced water stress.