Estimation of Canopy Height in Zambia through Integration of GEDI, Sentinel-1 and Sentinel-2 Measurements

Accurate canopy height estimation is critical for forest management and carbon monitoring in Zambia’s ecologically diverse landscapes. This study developed a high-resolution canopy height model by integrating multi-sensor remote sensing data—NASA’s GEDI LiDAR, ESA’s Sentinel-1 SAR, and Sentinel-2 optical imagery—using a Random Forest algorithm. The approach addressed key limitations of sparse GEDI sampling (25 m footprints) through fusion with continuous 10 m-resolution Sentinel-1/2 data and SRTM elevation metrics, processed via Google Earth Engine. The model achieved robust performance, with training accuracy of r2 = 0.76 (RMSE = 2.1 m) and validation accuracy of r2 = 0.71 (RMSE = 2.3 m), representing relative errors of 13.1–14.3%. Analysis revealed a bimodal height distribution (Hartigan’s dip test: p 30 m, 5.0%) in protected highlands. Variable importance analysis ranked GEDI’s RH98 metric (38%) as most influential, followed by Sentinel-2’s NIR band (22%) and Sentinel-1’s VH polarization (17%). Topographic correction using SRTM reduced errors by 23% in escarpment regions. These results demonstrate the synergy of LiDAR, SAR, and optical data for national-scale canopy mapping, particularly in heterogeneous tropical ecosystems. The 2-m height discrimination capability supports Zambia’s REDD+ monitoring, enabling targeted conservation of carbon-rich miombo woodlands and biodiversity refugia. Future work should integrate ICESat-2 and wet-season SAR data to address dry-season bias and fragmented canopy limitations.