1. Dept. of Hydraulics Works, Instituto de Pesquisas Hidraulicas, Universidade Federal do Rio Grande do Sul, IPH/UFRGS, Av. Bento Gonçalves, 9500, 91501-970, Porto Alegre, Rio Grande do Sul, Brazil (corresponding author).
2. Professor, Dept. of Civil and Water Engineering, Universite Laval, Ville de Québec, QC, Canada G1V 0A6.