Large fluctuations in the sediment transport rate are observed in rivers, particularly in mountain streams at intermediate flow rates (Ancey, 2006). These fluctuations seem to be, to some degree, correlated with the evolution of morphologies in the stream. Today the central question remains how to understand and acco unt for the strong bedload variability. In this presentation, new experimental results give some ideas about the link between channel bed evolution and intermittency in bedload transport.