Soil Sealing Monitoring for Sustainable Land Management in Estonia: Copernicus, National Data, and Reference-Based Assessment

Reliable soil sealing monitoring supports sustainable land management by identifying persistent soil degradation and the loss of soil functions. This study evaluated CLC+ Backbone (CLC+ BB), Imperviousness Density (IMD), and an object-based proxy derived from the Estonian Topographic Database (ETD). National estimates were compared across available reference years, and a stratified sample of 1500 orthophoto-interpreted 10 × 10 m units was assessed for 2021. A separate probability-based yard assessment evaluated omissions from the ETD-derived proxy and their sensitivity to the operational surface definition. The datasets yielded markedly different area estimates and temporal patterns: for 2021, direct national estimates ranged from 330.1 km2 for IMD to 715.0 km2 for CLC+ BB, while the broader reference-based estimate was 732.3 km2 (95% CI: 643.6–882.4 km2). Similarity between the CLC+ BB and reference totals concealed both omission and commission errors. Under the broader operational definition, estimated ETD-proxy omission was 2.6% (95% CI: 2.0–3.2%) in private yards and 26.5% (18.9–34.7%) in production yards. Narrowing the definition reduced the estimates by similar proportions in both yard types but produced a much larger absolute reduction in production yards. The results support integrated monitoring combining European products, national data, and reference-based validation for sustainable land management and soil protection.