Streamflow permanence curve of the river Timbó, Santa Catarina, Brazil

Abstract

The permanence curve is used as a source of information on water availability. It is adopted as a reference in the processes of management of water resources. In the present study, the streamflow permanence curve of the Timbó River, located in the Northern Plateau of Santa Catarina, was evaluated and modeled. Daily streamflow data of the fluvial station Santa Cruz do Timbó (Code 65295000) were used for the period from 1975 to 2005. Thus, permanence curves can be established for monthly streamflows and daily streamflows. The values were rendered dimensionless by the average long-term streamflow, and adjusted to the Rational model. The daily streamflow permanence curves were also determined for each month, and the models for these non-dimensioned streamflows were adjusted by the average monthly streamflows. The results show that the use of the monthly permanence curve overestimates the streamflow values by frequencies higher than 20%. The adjusted models allow estimating the streamflow with a small estimation standard error. The coefficient of determination is higher than 0.99.