Quadros, Clécio José Lopes de 
DGPS AND GIS USED AS TOOLS FOR THE ANALYSIS AND MODELLING OF BEACH RIDGES 
ON THE BRAZILIAN SOUTH COAST 
Clécio J. L. de QUADROS, Mauricio A. NOERNBERG, Luiz F. C. LAUTERT 
Federal University of Paraná, Brazil 
Center for Marine Studies 
cleciolq@cem.ufpr.br, mauricio@cem.ufpr.br, luizfer@cem.ufpr.br 
KEY WORDS: GIS, DGPS, Beach Ridges, Thiessen Method, DEM. 
ABSTRACT 
The beach ridges are prolonged accumulations, in general of sandy composition, disposed parallel to 
the ancient shoreline and separated to each other by depressions. They are formed by the action of storm waves, 
currents and in a lesser extend by tides, constituting progradation zones. The portion of beach ridges studied is 
an increment in the shoreline accumulated in the last 40 years, that correspond the succession of these ridges, 
inserted by narrow and prolonged marshy strips, covered by typical vegetation, or small ponds, where the 
altitudes vary between 0.78 a 3.85m. This coastal plain area is located in Paraná State, Brazil (25? 34-30'S; 48? 
20-25'W). 
The studied area shoreline has typical variations of outlet of bays. Certain sections of the beach show a 
progress of approximately 700m in 40 years, with medium progress of 17,5 m/year. 
Studies for the preservation of these beach ridges are of great importance because it is the last and well 
preserved “restinga” (sand dune vegetation) of the coast on state of Paraná, and it also represents an important 
stop point for resting and feeding of migratory birds. 
With the purpose of obtaining information that allowed the construction of a digital elevation model 
and of thematic maps of the area, several field survey were accomplished using DGPS Ashtech Realiance 
Decimeter package. Firstly, the mapping of the area contour and drainage mesh was accomplished. Later on, 48 
profiles of perpendicular points to the shoreline were made. For each point the data obtained by DGPS, 
including observed data relief morphology was stored. These data were post-processed on the Reliance 
processor software and the points that did not have inferior accuracy to 0,5 m were discarded. For the whole 
study area, 2.2 km”, were obtained a total of 933 points. 
The data were worked in the SPANS GIS, generating a digital elevation model using the triangulation 
method and a resolution of 6.4 m. Morphology forms maps were also generated, using the Voronoi method for 
the data interpolation. 
In spite of the great morphologic diversity of this environment type, the obtained results were 
satisfactory. The digital elevation model did not resulted in a faithful reconstruction of all the features of the 
area. This is due to the small variation in the height of the features, being close to the limit of the resolution 
reached by DGPS in the altitude (0,5 m). However, it characterized the main ridges and swales, obtaining a 
good concordance with the morphology forms maps. 
This survey type was efficient for the characterization of small areas, even having little altimetric 
variation of its relief morphology. The information generated by this survey will be of great usefulness for the 
understanding, planning and monitoring of this ecosystem. 
1. INTRODUCTION 
The inlets are met on the transition between the protected environment of the estuaries and the open 
sea. These geomorphological forms are subjected to a complex interaction of natural agents like: tides, tide 
currents, meteorological variables, waves and drift currents. 
It is very common at these areas the formation of beach ridges that, according to Suguio (1998), consist 
on elongated depositional forms, in general with sandy composition, with parallel disposition to the 
palaeoshorelines and separated one from the other by swales. It is formed by storm waves activity, currents, and 
  
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 1199