INFLUENCE OF THE HYDROELECTRIC POWER PLANT OF PASSO FUNDO LAKE (RS, BRAZIL) ON LOCAL RAINFALL PATTERN

The present study examined the influence of the Hydroelectric Power Plant (HPP) of Passo Fundo dam lake on local rainfall pattern. Daily rainfall data were obtained from the National Water Agency for two different periods: prior to the lake filling, 1960-1970 (pre-filling) and later to the lake filling, 1971-1981 (post-filling). Statistical measures (mean, maximum, minimum, standard deviation and coefficient of variation) and the Student’s t-test were applied to both periods regarding the monthly rainfall total. The Student's t-test was also applied to days with cumulative rainfall greater than 1 mm, 10 mm, 20 mm, 30 mm, 50 mm, 80 mm and 100 mm, to the number of dry days and to the monthly largest dry period. The results showed that only days with cumulative rainfall exceeding 50 mm (July), number of dry days in the month (June) and the monthly largest dry period (May and Nov) were influenced due to the formation of the dam lake