Geodetic method to obtain a digital elevation model associated to the Brazilian Geodetic System

— The present paper presents a geodetic methodological proposal used to link limnimetric ruler to the Brazilian Geodetic System (SGB) and obtain a Digital Elevation Model (MDE) applied to flood areas also linked to the GBS. The bond of the rules to the GBS was given by the geometric levelling using as a starting point a Reference of Level (RN) of the Basic Altimetric Network of Brazil (RAFB) and finalizing in one of the limnimetric rules implanted by the Geological Service of Brazil (CPRM) the margins of the Uruguay River. The coordinates within the study area were determined by the relative static positioning of the GNSS, using as reference a forced centering frame whose coordinates were obtained by Positioning by Precision Point (PPP) made available by the Brazilian Institute of Geography and Statistics (IBGE). The orthometric altitudes were determined by relative mode GNSS altimetry, using an RN together with the IBGE gravimetric geoid, and the MDE was generated in ArcGis environment using the top to raster interpolator. The resulting MDE allowed the delimitation of the areas constantly affected by the floods based on the data provided by the CPRM and monitoring of the level of the river and the areas affected during the flood of the year 2017.