19 files

Frequency analysis of minimum flows

Download all (675 kB)
posted on 06.06.2018, 02:42 by Adelita Ramaiana Bennemann Granemann, Miriam Rita Moro Mine, Eloy Kaviski

ABSTRACT The study of minimum flows is increasingly important due to the relationship with ecosystem sustainability, the economy and its role as a sentinel of climate change. The aim of this paper is to contribute to the theoretical treatment of minimum extremes and, specifically, minimum flows. The method has two approaches: i) conventional; ii) asymptotic. In conventional analysis, the Weibull (W2) and Lognormal distributions of two parameters (LN2) were adjusted to the series of annual minimum flows and minimum averages of 7-day flows. In the asymptotic analysis approach two parent distributions, the distributions of all average daily flows, with power behavior for minimum flows, are investigated: i) Gamma; ii) LN2. The theory studied in this paper is applied to 11 gauged stations in the Iguaçu river basin with 48-year data series. It was concluded that the LN2 distribution presents the best fit according to the χ 2 test. It was found that the Gamma distribution, with respect to the minimums, tends to a power function, and consequently the W2 distribution. The parameters k, b and μ X , of the normalized annual minimum flow series are well-fitted to the LN2 distribution. According to both approaches, LN2 can be recommended for studies of minimum flows in the Iguaçu river basin.