A study of drainage network accomplished with the help of aerial photographs in areas of oxisols and ultisols occurence is presented. The study area with approximately 600km², is located in the Peripheral Depression in the Iracemapolis region, state of São Paulo. The composition of natural drainage networks of the third order of ramification of the studied areas was determined through watersheds which were selected by the principles of geometrical similarity and same order of ramification. The oxisols region is formed by cleyey soils developed from basic rocks and the ultisols area is formed by soils developed from sandstone or shale. The analysis of parameters: number, total length and mean length of stream segments was done with each area unit. The drainage density appeared to be the best parameter to differentiate between soil mapping units.
drainage density; aerial photography; textural B soils; latossolic B soils