def METHOD_NAME(self, dt):
    """
    Advance by one time step.
    Parameters
    ----------
    dt : float
        Time-step duration (y)
    """
    z_before = self.grid.at_node["topographic__elevation"].copy()
    self.calc_diffusion_coef()
    super().METHOD_NAME(dt)
    depo = self.grid.at_node["sediment_deposit__thickness"]
    depo[:] = self.grid.at_node["topographic__elevation"] - z_before
    self._time += dt