1. Professor, Dept. of Hydrology and Water Resources, Univ. of Arizona, Tucson, AZ 85721; and Universidad de Antioquia, Medellín, Colombia (corresponding author).
2. Professor, Dept. of Civil Engineering, Universidad de Castilla La Mancha, 13071 Ciudad Real, Spain.
3. Professor, Dept. of Civil Engineering and Engineering Mechanics, Univ. of Arizona, Tucson, AZ 85721.