Standardization of the elevation in the AW3D30 global digital elevation model to the Vietnamese national vertical datum: An experiment in Ninh Binh province and surrounding areas

Abstract

This study proposes a method for standardizing the elevation of the ALOS World 3D–30 m (AW3D30) global digital elevation model to the Vietnamese national vertical datum, using national GNSS/levelling data from Ninh Binh Province and surrounding areas. The correction procedure consists of three main steps: (1) collecting GNSS/levelling data, global DEM data, and EGM96 geoid model data to ensure accuracy and consistency; (2) determining correction parameters to transform AW3D30 global elevations to local heights, including analysis of differences between global and local geoid models and assessment of tidal effects; and (3) verifying, correcting, and evaluating the accuracy of the AW3D30 model after transformation to the national vertical datum. The experimental results indicate that, after correction, the root mean square error of the AW3D30 model relative to the national height system is ±1.613 m, while the maximum deviation between AW3D30 elevations and GNSS/levelling heights is reduced from 9.014 m to 5.238 m. Approximately 91.7% of the GNSS/levelling points exhibit deviations within the acceptable range, demonstrating that the proposed method significantly improves the accuracy and applicability of AW3D30 in the national vertical datum. The method can be extended to other regions of Vietnam as well as to other global digital elevation models. These findings contribute to enhancing the accuracy of topographic data in support of spatial planning, resource management, disaster forecasting, and related applications.