1. Dep. of Civil, Construction, and Environmental Engineering Iowa State Univ. Ames IA 50011 USA
2. Dep. of Natural Resource Ecology and Management Iowa State Univ. Ames IA 50011 USA
3. Dep. of Ecosystem Science and Management Pennsylvania State Univ. State College PA 16801 USA
4. Dep. of Civil and Environmental Eng. Auburn Univ. Auburn AL 36849 USA