Temporal completeness reveals long-term hydroclimatic trend reversal: a multi-temporal remote sensing assessment of Lake Belevi (Türkiye), 2000–2026

Abstract Climate-induced hydrological change increasingly threatens Mediterranean freshwater systems, yet many satellite-based monitoring studies end before the recent sequence of severe droughts, potentially biasing long-term trend assessments. This study presents a temporally complete 26-year (January 2000–April 2026) hydroclimatic assessment of Lake Belevi (İzmir, Türkiye) using 273 monthly Landsat-derived surface water observations integrated with CHIRPS precipitation, ERA5 temperature, and watershed NDVI within Google Earth Engine. Seasonal Mann–Kendall analysis of the full series revealed a significant decreasing trend (p = 0.014, Sen slope = − 1.27 ha month⁻¹), whereas the truncated 2000–2020 record showed a significant increasing trend (p = 0.008), suggesting that extending observations beyond recent droughts can change the inferred direction of long-term hydrological trends. PELT detection identified five hydrological regime shifts (2005, 2013, 2016, 2022, and 2025), while the 2025 drought reduced lake area to 4.7 ha (96.5% below the 2013–2016 peak), followed by rapid recovery to 180.7 ha by February 2026. Watershed NDVI increased significantly (+ 53.2%, p < 0.001) despite declining water extent. These findings indicate that temporally truncated satellite records may underestimate drought-induced hydrological degradation and even reverse the inferred direction of long-term trends, supporting more robust climate-change attribution and adaptive water-resource management.