Caracterização hidrológica e de atributos físico-hídricos dos solos da bacia hidrográfica do Rio Cabelo, utilizando sistemas computacionais livres.

Abstract

The work was conducted on the Rio Cabelo hydrological micro basin, located in João Pessoa, State of Paraíba, Brazil, aiming to establish hydrologic parameters of the basin and characterize physic-hidrically the existing soils and their spatial variability. All the procedures used in the study were executed through out free computational systems, the R Statistical and the SIG GRASS system. During the elaboration of the Land Numerical Method (MNT) the Spline Line interpolation methods, with regularized tension, gave altitude values closer, than those obtained when used the universal kriging, and also had a better performance according with the AIC and Quadratic Error Mean criterion for model selection. The basin had an area of 9,786 Km2 and the flux lines a predominant dendritic estructure. When constructing the empirical semivariograms, during the geoestatístic analyses of the soil parameters, using boxcox transformations of the data, with and without removal of linear trend, it was observed that with exception of the 60- 90cm particle density data, the trend removal permitted to predict values very much closer than the obtained in the field. To estimate the parameters of the covariance models (spherical, exponential, gaussian, matern, powered-exponential, cauchy) were utilized the Ordinary Least Squares (OLS), Weight Least Squares (WLS) and Maximum Likelihood (ML) methods. This last one, presented resulted more reliable than the OLS and WLS methods, when considered the AIC and Maximum Likelihood logarithm criterion for the models selection. The space dependence range of the models, were established for prediction of values not sampled for the textural separates clay, silt, sand, for soil density, particle density and for the hydraulic conductivity.