1. Grad. Res. Asst., Iowa Inst. of Hydr. Res., The Univ. of Iowa, Iowa City, IA 52242.
2. Prof., Iowa Inst. of Hydr. Res., The Univ. of Iowa, Iowa City, IA (corresponding author). E-mail: witold-krajewski@uiowa.edu.
3. Asst. Res. Engr., Iowa Inst. of Hydr. Res., The Univ. of Iowa, Iowa City, IA.