Avalanche merging and continuous flow in a sandpile model

A dynamical transition separating intermittent and continuous flow is obser ved in a sandpile model, with scaling functions relating the transport beha viors between the regimes. The width of the active zone diverges with syste m size in the avalanche regime but becomes very narrow for continuous flow. The change of the mean slope. Delta z, on increasing the driving rate, r, obeys Delta z similar to r(1/theta). It has a nontrivial scaling behavior i n the continuous flow phase with an exponent theta given, paradoxically, on ly in terms of exponents characterizing the avalanches theta = (1 + z - D)/ (3 - D).