Multi-temporal Sentinel-2 and Machine-Learning Assessment of Lake Urmia Restoration Dynamics
摘要
Using cloud-minimized Sentinel-2 Level-2A scenes (August 2017 pre-restoration; August 2024 post-restoration), we mapped Water, Salt-flat, and Non-Water-Salt over Lake Urmia to evaluate changes around the Kani Sib inter-basin transfer within the Urmia Lake Restoration Program (ULRP). Three off-the-shelf classifiers, Random Forest (RF), Gradient Boosting (GB), and Decision Tree (DT), were trained on stratified samples. RF delivered the highest overall accuracies (2017: 87.6%; 2024: 80.7%), outperforming GB (85.1%, 78.4%) and DT (80.2%, 74.9%). A 3 × 3 majority (“sieve”) filter improved spatial coherence and raised overall accuracy by ~0.7–0.8 percentage points. Transition mapping shows localized water gains along the southern shoreline near the transfer corridor, but expansion of salt flats in the northern basin; pixel accounting yields a net open-water loss of ~88.6 km2 from 2017 to 2024. We infer that while targeted inflows locally replenished margins, basin-wide desiccation driven by abstraction and evaporation dominated. The findings motivate an integrated water-management strategy that couples controlled transfers with basin-wide demand reduction, real-time monitoring (e.g., Synthetic Aperture Radar (SAR), thermal infrared (TIR)), and community engagement to support climate-resilient governance in Lake Urmia and analogous endorheic systems.