Procedimentos para aprimorar a regionalização de vazões: estudo de caso da bacia do Rio Grande / Procedures to improve the hydrologic regionalization: study of Rio Grandes basin

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The hydrologic regionalization constitutes an efficient instrument to plan and manage the water resources, and it can be used to obtain the hydrological variables, as the maximum, minimum and medium discharges, in a simple and fast way. This technique can minimize the absence of hydrologic information in sites with low or no data availability. However, some problems related with the inconsistence of the data and the presence of dams in the hydrographic network can interfere in the regionalizations equations adjustment. Considering this context, the objective of this work is to suggest a statistical criterion to identify the fluviometric stations with inconsistent data; and to propose procedures to analyze the spreading of the reservoirs effect in the hydrologic regionalization studies, conducing a specific study to the Rio Grandes basin. It was suggested to use the Box Plot technique to identify the presence of discrepancies in the regionalization dataset. Thus, adopting the results found in the Box Plot graphic, it was conduced the regionalization of the medium discharge of long term (Qmld), the minimum discharge with a return period of ten years (Q7,10), the discharges associated with the permanence of 90% (Q90) and 95% (Q95) and the maximum discharge with a return period of 100 years (Qmax) to the Rio Grandes basin. In the case of the Grande and Pardos rivers the regionalization utilized data of natural discharges. It was analyzed the use of the following independents variables: drainage area, annual total rain, equivalent rain and hydric inertia. The selection of the best regionalization model was based in the relative residues and in the physic behavior of the discharge. The analysis of the spreading of the reservoirs effect started with the exclusion of the fluviometric stations influenced by the regularizations effect of the hydrologic regionalization study. The influence was measured by two indexes: the potential of regularization index and the contribution index. The relative variation between the estimatives of the minimum (Q95) and the maximum discharge was used to evaluate the reservoirs effect, where the medium discharge was considered the control of this analysis. The results showed that: a) the application of the Box Plot presented a good potential to improve the hydrologic regionalization of the medium and minimum discharges, in otherwise, in the maximum discharge study the use of this technique presented some restrictions; b) the use of the variables equivalent rain or drainage area produced the best statistical adjustments, however the use of the drainage area tended to overestimate the discharges compared to the use of the equivalent rain; c) in the natural discharges study, the use of the drainage area generated more consistent results; d) the procedures proposed to analyze the reservoirs effect in regionalization studies presented similar results and the consideration of this effect in the Rio Grandes basin had low expressivity in the estimatives of the minimum and maximum discharges.

ASSUNTO(S)

water resources disponibilidade hídrica water availability recursos hídricos conservacao de solo e agua

ACESSO AO ARTIGO

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