Analysis and Selection of the Best Global Geopotential Model for Lebanon: Case Study Rashya District

Accurate transformation of Global Positioning System (GPS) derived ellipsoidal heights to orthometric heights necessitates the selection of an optimal Global Geopotential Model (GGM). This study aims to identify the most accurate freely available high-resolution GGM for Lebanon. The performance of five GMs, Earth Gravitational Model 2008 (EGM2008), SGG_UGM_1, SGG_UGM_2, GECO, and XGM2019e, is assessed. Geoidal undulation values are extracted for 28 geodetic benchmarks in the Rashaya district using a Geographic Information System and compared with reference data from the Lebanese Directorate of Geodetic Affairs. Vertical accuracy is quantified using the mean deviation (DN), standard deviation, and root mean square error (RMSE) between GGM-derived and reference heights. The analysis reveals that XGM2019e provides the highest accuracy, with the smallest mean deviation (DN = –0.25 m) and the lowest RMSE (±1.09 m). These results establish XGM2019e as the optimal GGM for Lebanon, ensuring precise height transformation and supporting advanced geodetic and geospatial analyses.