Bistability and hysteresis in tilted sandpiles

We show that tilting a model sandpile that has dynamic disorder leads to bistability and hysteresis at the angle of repose. Also the distribution of local slopes shows an interesting dependence on the amount of tilt weakly tilted sandpiles retain the quasicontinuous distributions of the steady state while large tilt makes the distribution more discrete with local slopes clustered round particular values. These observations are compared with recent experimental results on avalanche shapes. We also consider the percolation of local instability and anomalous roughening of the sandpile surface.