Multivariate analysis of factors influencing the peak flow and runoff volume in the Cerrado and Atlantic Forest biomes in Brazil.

This study evaluates the influence of physiographic characteristics on the peak flow to runoff volume ratio in watersheds belonging to the Cerrado and Atlantic Forest biomes, in the Center-South region of Brazil. Specifically, the peak flow and runoff volume values obtained in the outlet section are related to the physiographic characteristics of the watersheds. Using a geographic information system tool, 13 watersheds are delimited, and 38 variables are selected from each watershed. A recursive digital filter is used to separate the direct (surface) flow from base (groundwater) flow. Data are analyzed using multivariate statistics, which allows interpretation of the structure of a data set from the respective correlation matrices. The results indicate that the peak flow and runoff volume are strongly correlated with the physical characteristics of the watersheds and the types of anthropogenic activity in both biomes. Furthermore, the presence of woods and forests reduces the peak flow and runoff volume.