Regionalização hidrológica na região do alto rio Paraíba-PB utilizando dados simulados com modelo distribuído.

Abstract

The estimation of hydrological variables in ungaged homogeneous regions is the main objective of regional analysis. In general, the hydrological time series are either of short length or discontinuous. To cope with such a problem, hydrologic models are used in order to simulate long time series. In this research, mean daily discharges were generated at nine sub-basins of the Paraiba river basin (-13000 km2) in the state of Paraiba, located in the semiarid Northeast region of Brazil, with the model NAVMO, using parameters previously calibrated for four sub-basins with available data. Parametric and nonparametric tests were applied to the simulated mean and maximum annual series of discharges in order to verify their consistency and homogeneity. Typical distributions of probability were investigated with the Ko 1 mogorov-Smirnov test (K-S test) and regression analyses (simple and multiple) between the hydrological variables and basin characteristics (climate and physical) were employed to establish relationships capable of predicting the interested variables at ungaged places. The simulations showed that, in general, the calibrated model NAVMO was capable of simulating the discharges with reasonable consitency and homogeneity. The K-S test showed that the Gam a and Gumble distributions of probability best fit the empirical frequencies of the maximum dischages, while the Lognormal best represented the mean discharges. According to the regression analyses, the basin area and river length were the most important explanative physical variables. Also, the inclusion of other variables (e.g., basin slope, drainage density and precipitations) increased the results, but not markedly. Based upon regression analyses (simple and multiple) relationships capable of estimating maximum discharges for required return periods, discharges with 95% of permanency and long time mean discharges were established in terms of physic and climatic variables at ungaged basins.