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Universidade de Brasília (UNB) 2015

Estimativa de séries anuais de evapotranspiração real e vazão em bacias sem monitoramento fluviométrico com base nas hipóteses de budyko

Otsuki, Rodrigo Gomes

Titre : Estimativa de séries anuais de evapotranspiração real e vazão em bacias sem monitoramento fluviométrico com base nas hipóteses de budyko

Estimative of annual actual evapotranspiration and streamflow series at ungauged basins based on budyko hypothesis

Auteur : Otsuki, Rodrigo Gomes

Université de soutenance : Universidade de Brasília (UNB)

Grade : Mestrado em Tecnologia Ambiental e Recursos Hídricos 2015

Résumé
Estimating hydrological variables at ungauged basins is one the greatest challenges in Hydrology. Budyko, Russian climatologist, studied the water behavior in nature and presented ideas known as the Budyko hypotheses. Based on these hypotheses, several methods have been proposed, allowing the calculation of actual evapotranspiration (E) and streamflow (Q) based on precipitation (P) and potential evapotranspiration (E0). This study explored the use of the Fu’s equation, a uni-parametric model based upon Budyko’s ideas, in the estimation of long-term averages and annual time series of E and Q in gauged and ungauged basins. Two different and heterogeneous regions in Brazil were chosen to evaluate the methodology, one in mostly semiarid basins in the state of Ceará, and the other in more diversified climatic conditions in the São Francisco River basin. For each basin, the solely ω parameter of the Fu equation was calibrated for long-term and annual time scales, and results for both scales were similar. Regional regression models of the parameter ω were developed for the two studied regions for both time scales so one can use the equation for ungauged basins. This study was based on physical and climatological characteristics of the basins as well as Weighted Least Squares (WLS) regionalization techniques. For the long-term scale, the average Nash-Sutcliffe (NS) coefficients were high, being approximately 0,90 for E and 0,80 for Q for the Ceará basins. The estimated average NS coefficients for the São Francisco river subbasins were approximately 0,72 and 0,88 for E and Q, respectively. Regarding the annual scale, results were in general lower than those obtained for the long-term scale. For the prediction of annual E of the Ceará, 88% of the basins had NS greater than 0.50 and 63% had NS greater than 0,90. For the prediction of Q annual series, 80% of the basins had NS greater than 0.50 among which 30% were greater than 0.70. For the prediction of annual E series of the São Francisco sub-basins, 60% of the results were greater than 0.50 and 30% greater than 0,70. On the other hand, on the prediction of annual Q series, only 56% of the São Francisco sub-basins had positive NS.

Mots Clés : bacias sem monitoramento, regionalização, modelos tipo Budyko, evapotranspiração ungauged basins, regionalization, Budyko-like methods, evapotranspiration

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Page publiée le 28 juillet 2017