High-precision geoid determination in small areas: A case study in Doñana National Park (Spain)

• DOI: 10.1007/s11200-008-0026-y
• Publication Date: 2008-09-11T06:18:04Z
• Authors: M. A. Núñez; A. Martín; J. A. Gili; A. B. Anquela
• Keywords: 15. Life on land; 01 natural sciences; 0105 earth and related environmental sciences

Donana National Park is an area of approximately 500 km2 located on the SW coast of Spain that shows one of the greatest geoid gradients on the entire Iberian Peninsula, due to its peculiar tectonic characteristics. So, it is necessary to elaborate an accurate geoid model that can be used with GPS for precise surveying, since the existing ones are insufficient, due to their poor resolution and their limited adaptation to a small area with such a strong gradient. The least squares prediction method was tested in order to obtain the undulation from GPS/orthometric points. The results obtained were unsatisfactory because of the strong geoid gradient. In order to improve accuracy the remove-restore technique was used. Global geopotential model EIGEN-CG01C and a Digital Elevation Model (DEM) with a 25 × 25 m resolution and an accuracy better than 3 m were used. Thus, the final geometrical geoid obtained reaches the precision required by other disciplines (3 cm in any point within the Park). Particularly, the geoid model has allowed for the acquisition of a precision DEM that is essential to formulate a hydrodynamic model for the Donana marsh functions.