Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 2 1 1998 10.5194/hess-2-1-1998 http://www.hydrol-earth-syst-sci.net/2/1/1998/ http://www.hydrol-earth-syst-sci.net/2/1/1998/hess-2-1-1998.html http://www.hydrol-earth-syst-sci.net/2/1/1998/hess-2-1-1998.pdf 1 8 0000-00-00 The geomorphological unit hydrograph – a critical review A. Y. Shamseldin J. E. Nash Department of Engineering Hydrology, National University of Ireland, Galway, Ireland The theory of the geomorphological unit hydrograph (GUH) is examined critically and it is shown that the inherent assumption that the operation of the drainage network may be modelled by a corresponding network of linear reservoirs so restricts the instantaneous unit hydrograph (IUH) shape that the effects of further restrictions, reflecting the constraints imposed by the geomorphological laws of the channel network, cannot easily be identified. Without such identification, the geomorphological unit hydrograph theory is untestable and must remain only a plausible hypothesis providing an indication of a two-parameter IUH whose shape and scale factors must still be related empirically to appropriate catchment characteristics.