1. Faculty of Science and Technology, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Aas, Norway
2. Department of Hydraulic and Environmental Engineering, Norwegian University of Science and Technology (NTNU), S. P. Andersens vei 5, Trondheim 7491, Norway
3. University of South-Eastern Norway, Kjølnes ring 56, Porsgrunn, Norway