1. a Faculty of Hydraulic and Water Resources Engineering, Arba Minch University, Arba Minch, P.O. Box 21, Ethiopia
2. b Faculty of Water Resources and Irrigation Engineering, Arba Minch University, Arba Minch, P.O. Box 21, Ethiopia
3. c Faculty of Engineering, Department of Civil and Environmental Engineering, Namibia University of Science and Technology, Namibia