NUNES, A. S. O.; http://lattes.cnpq.br/9448543489942649; NUNES, Aracy Siqueira de Oliveira.
Resumo:
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.