A multi-class, multi-temporal crop and Land cover mapping framework for Morocco using Sentinel-1/2 monthly composites and advanced machine learning ensembles

Maryam Choukri, Yacine Bouroubi, Jamal-Eddine Ouzemou, Said Grich, Guy Armel Kamga Fotso, Saeid Ojaghi, Abdelghani Chehbouni, Ahmed Laamrani

Timely and accurate crop-type mapping is fundamental for sustainable agricultural management and food security in semi-arid regions, where climate variability and fragmented landscapes present persistent challenges. This study develops and validates an operational, multi-temporal framework for classifying five key agricultural classes (i.e., soft wheat, durum wheat, barley, trees, and other crops) across diverse Moroccan agroecosystems. By integrating monthly Sentinel-1 Synthetic Aperture Radar and Sentinel-2 optical time series spanning six growing seasons (2018–2025), we extracted 156 features comprising 13 spectral indices across 12 monthly composites. Ground truth data from the national Al Moutmir database, strategically balanced to address natural class imbalances, supported comprehensive training and validation of six machine learning models (i.e., Random Forest, Extra Trees, XGBoost, LightGBM, Voting Ensemble, and Stacking Ensemble). Our findings showed that the LightGBM and Stacking Ensemble achieved the highest performance with 88.04% overall accuracy, followed closely by XGBoost (87.93%). Feature importance analysis revealed that monthly temporal resolution significantly outperformed traditional phenological-stage approaches, with March and April indices (particularly Normalized Difference Vegetation Index and Normalized Difference Red Edge) contributing most to class discrimination. Notably, early-season radar features (Vertical-Vertical polarization in September) provided valuable complementary information when optical data were limited. The framework demonstrated robust generalization through 10-fold cross-validation while explicitly quantifying a 12.56% overfitting gap (train-CV difference), acknowledging a non-negligible overfitting risk. Offering transparent performance assessment. Error analysis identified persistent confusion between spectrally similar cereals, particularly durum and soft wheat, highlighting priority areas for future sensor integration. This scalable, cloud-based pipeline directly supports Morocco’s Green Generation strategy by providing a reproducible, high-accuracy solution for annual crop inventories, with transferable applications across similar Mediterranean and semi-arid agricultural systems.