1. Research Hydraulic Engineer, Bureau of Reclamation, P.O. Box 25007, Denver, CO 80225 (corresponding author).
2. ATB Riva Calzoni SpA, 25030 Roncandelle (BS), Via Industriale, 13, Italy; formerly, Research Assistant, Technical Univ. of Bari, Via Amendola, 126/B, 70126 Bari, Italy.
3. Professor, Dept. of Civil Engineering, Architecture and Georesources, Instituto Superior Técnico, Univ. of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal.