Integrated satellite–UAV analysis of long-term desiccation of a natural heritage lake through volumetric reconstruction: The case of Meke Lake, Türkiye

Natural heritage lakes in semi-arid regions are highly vulnerable to groundwater depletion and drought, yet their long-term volumetric dynamics are rarely quantified where in-situ hydrometric observations are limited. To move beyond conventional two-dimensional (2D) surface-area monitoring, this study integrates Landsat-derived annual water boundaries, a centimeter-level Unmanned Aerial Vehicle (UAV)-based Digital Elevation Model (DEM), and groundwater drought indicators to reconstruct historical stage–area–volume dynamics in a small, data-scarce volcanic lake. The framework was applied to Meke Lake, Türkiye, a groundwater-dependent closed-basin maar lake. Landsat imagery from 1985 to 2025 was processed using the Modified Normalized Difference Water Index (MNDWI). Valid annual water boundaries from 1985 to 2020 were used for DEM-integrated area–volume reconstruction, whereas the 2021–2025 images were used only to verify the post-desiccation condition because no spatially continuous surface water boundary was detected after 2020. The results show that lake surface area declined from approximately 0.49 km2 in the mid-1980 s to less than 0.06 km2 by 2020. Water storage decreased more sharply, from peak values exceeding 600,000 m3 to 7,447 m3 by 2020, corresponding to a loss of more than 98% of peak storage capacity. The 2008–2009 and 2013–2014 periods mark critical decline phases driven by nonlinear basin morphology. This results indicate persistent groundwater drought after approximately 2007, while trend and change-point analyses confirm statistically significant long-term decline in lake area, volume, and groundwater drought indicators. The integrated satellite–UAV framework provides a transferable approach for assessing volumetric degradation in small, data-scarce natural heritage lakes.