  Most gravitational currents occur on sloping topographies, often in the
presence of particles that can settle during the current propagation. Yet, an
exhaustive exploration of associated parameters in experimental studies is
still lacking. Here, we present an extensive experimental investigation of the
slumping regime of turbidity (particle-laden) currents in two lock-release
(dam-break) systems with inclined bottoms. We identify 3 regimes controlled by
the ratio between settling and current inertia. (i) For negligible settling,
the turbidity current morphodynamics correspond to those of saline homogeneous
gravity currents, in terms of velocity, slumping (constant-velocity) regime
duration and current morphology. (ii) For intermediate settling, the slumping
regime duration decreases to become fully controlled by a particle settling
characteristic time. (iii) When settling overcomes the current initial inertia,
the slumping (constant-velocity) regime is not detected any more. In the first
two regimes, the current velocity increases with the bottom slope, of about
$35~\%$ between $0^\circ$ and $15^\circ$. Finally, our experiments show that
the current propagates during the slumping regime with the same shape in the
frame of the moving front. Strikingly, the current head is found to be
independent of all experimental parameters covered in the present study. We
also quantify water entrainment coefficients $E$ and compare them with previous
literature, hence finding that $E$ increases linearly with the current Reynolds
number.
