Drainage pattern in the characterization of soils and its relationship with weathering index

Abstract

Soil characterization by photopedology studies are important tools in soil survey. Aerial photographs were used in a study of drainage network and its quantitative and descriptive characteristics were obtained in four areas located in Paraná State, Brazil, in soils developed from basic and acid rocks. In the aerial photo 1:25,000 scale, circular sampling with 10 km² were selected, both developed from acid rocks. The parameters of drainage pattern permit to separate the soils developed from basic rocks and soils developed from acid rocks. The descriptive analysis was useful to differentiate the soil units, but was not so sensible as drainage density. The drainage density in circular sampling was the best index for characterization of soils units. Soils developed from acid rocks have different drainage pattern when compared with similar soils developed from basic rocks. The drainage density can be considered a weathering index for the same rock, for basic or acid rocks.