1. a Department of Hydraulic and Water Resources Engineering, Faculty of Civil and Environmental Engineering, Jimma Institute of Technology, Jimma University, Jimma, Oromia 378, Ethiopia
2. b Department of Civil Engineering, Faculty of Engineering, Stellenbosch University, Private Bag X1, MATIELAND, Stellenbosch, Western Cape 7600, South Africa
3. c Department of Water Resources Engineering, Adama Science and Technology University, Adama, Oromia 1888, Ethiopia