  We construct a driven sandpile slope model and study it by numerical
simulations in one dimension. The model is specified by a threshold slope
$\sigma_c\/$, a parameter $\alpha\/$, governing the local current-slope
relation (beyond threshold), and $j_{\rm in}$, the mean input current of sand.
A nonequilibrium phase diagram is obtained in the $\alpha\, -\, j_{\rm in}\/$
plane. We find an infinity of phases, characterized by different mean slopes
and separated by continuous or first-order boundaries, some of which we obtain
analytically. Extensions to two dimensions are discussed.
