Calibration of run-off coefficients considering different rainfall and run-off events and seasonal flows: case study for Laelay Wukro and GumSelassa watersheds - Abdurahman, M.A.; Mohn, R.; Coldewey, W. G.; Awulachew, Seleshi Bekele; Werner, J.; Kruse, B.; Klemm, O. (2008)