Geodésia aplicada à integração de dados topográficos e batimétricos na caracterização de superfícies de praia

Abstract

This work presents a methodology developed for survey, generation and evaluation of Digital Elevation Models (DEM) of beach surfaces (emerged and submerged sectors) of sandy coastlines from the integration of topographic and bathymetric data in situ, georeferenced with decimeter accuracy compatible to coastal geomorphological dynamics of short-term studies. The methodology consists of: a) surveying the onshore portion of the beach following the method of kinematic relative positioning using Global Navigation Satellite Systems (GNSS) with the help of a motorized quadricycle; b) bathymetric survey of the submerged portion of the beach profi le supported by vessel equipped with echo sounder and GNSS receiver operating in kinematic relative mode; and c) data integration of topographic and bathymetric surveys to obtain more realistic DEM beach profile. The GNSS positioning involved in topographic and bathymetric surveys were executed relative to control stations of the geodetic position network to the study area, providing geodetic reference to Geodetic Brazilian System (GBS), which is univocal, fixed and relatively stable over time. The methodology was applied to Ponta Negra Beach, northeast Brazil, characterized by intensive human occupation and coastal erosion, offering a motivating demand to the potentiality of the proposed procedure related to survey productivity and accuracy of results, doubtless proving a progress achieved compared to classical methods of surveying entire beach profiles