Results observed from a laboratory study concerning the degradation of an alluvial channel owing to the flow of clear water are reported. Two sizes of sand, of median diameter 0.47 mm and 0.79 mm and geometric standard deviation 4.65 and 3.54, respectively, are used as a bed material. This paper focuses on studying the variation of the surface layer size with time and distance, the variation of sediment discharge with time, the sediment size of the armoured layer, and the time required for stabilization of the channel bed. Some useful equations for predicting the sediment size of the armoured layer and the total time for the degradation are also given.