INFLUENCE OF DATA AND INTERPOLATOR SELECTION FOR MAPPING THE RAIN DISTRIBUTION PATTERN IN THE BABITONGA BAY REGION, SOUTHERN BRAZIL

F.A. Oliveira

University of Joinville, Department of Geography, Joinville, Brazil

fabiano.o@uol.com.br

The Babitonga Bay is a 1560km² estuarine system located on the border of the Serra do Mar mountain range, which runs along part of the brazilian southeastern and southern coast. The surrounding area of the bay is formed mainly by 3 different environments: the coastal plain, the scarps of the Serra do Mar and the Atlantic Plateau, with an altitude variation from the sea level to 1520m over a straight line distance of less than 12km. The variety of topographic features has strong influence in the rain distribution pattern. The lack of rain distribution maps of the region in scales larger than 1:1.000.000 constitute a hindrance for environmental studies. The data used to accomplish a more precise 1:50.000 scale map were obtained in a 65-year historical series from 22 different climatologic stations. The DEM generated in the ArcMap 8.1 from the official cartographic base was used as base for interpolation procedures. Several tests were made with local, global and geostatistical interpolators, which generated 90 different maps. Results showed that small differences in data input with the same interpolator may result in significant variations of the rainfall contour lines. On the other hand, the use of the same set of data with different interpolators resulted also in distinct map drawing. The final map obtained with ordinary kriging makes evident the importance of field knowledge to guide the decision making process during the interpolation procedures in a GIS environment.